[PATCH bpf v3 00/15] selftests/bpf: Fixes for userspace ASAN

[PATCH bpf v3 00/15] selftests/bpf: Fixes for userspace ASAN

[Ihor Solodrai]

This series includes various fixes aiming to enable test_progs run
with userspace address sanitizer on BPF CI.

The first patch fixes the selftests/bpf/test_progs build with:

    SAN_CFLAGS="-fsanitize=address -fno-omit-frame-pointer"

The subsequent patches fix bugs reported by the address sanitizer on
attempt to run the tests.

---

v2->v3:
  - rebase on top of "selftests/bpf: Add and use strscpy()"
    - https://lore.kernel.org/bpf/20260220182011.802116-1-ihor.solodrai@linux.dev/
  - uprobe_multi_test.c: memset static struct child at the beginning
    of a test *and* zero out child->thread in release_child (patch #9,
    Mykyta)
  - nits in test_sysctl.c (patch #11, Eduard)
  - bpftool_helpers.c: update to use strscpy (patch #14, Alexei)
  - add __asan_on_error handler to still dump test logs even with ASAN
    build (patch #15, Mykyta)

v2: https://lore.kernel.org/bpf/20260218003041.1156774-1-ihor.solodrai@linux.dev/

v1->v2:
  - rebase on bpf (v1 was targeting bpf-next)
  - add ASAN flag handling in selftests/bpf/Makefile (Eduard)
  - don't override SIGSEGV handler in test_progs with ASAN (Eduard)
  - add error messages in detect_bpftool_path (Mykyta)
  - various nits (Eduard, Jiri, Mykyta, Alexis)

v1: https://lore.kernel.org/bpf/20260212011356.3266753-1-ihor.solodrai@linux.dev/


Ihor Solodrai (15):
  selftests/bpf: Pass through build flags to bpftool and resolve_btfids
  resolve_btfids: Fix memory leaks reported by ASAN
  selftests/bpf: Add DENYLIST.asan
  selftests/bpf: Refactor bpf_get_ksyms() trace helper
  selftests/bpf: Fix memory leaks in tests
  selftests/bpf: Fix cleanup in check_fd_array_cnt__fd_array_too_big()
  veristat: Fix a memory leak for preset ENUMERATOR
  selftests/bpf: Fix use-after-free in xdp_metadata test
  selftests/bpf: Fix double thread join in uprobe_multi_test
  selftests/bpf: Fix resource leaks caused by missing cleanups
  selftests/bpf: Free bpf_object in test_sysctl
  selftests/bpf: Fix array bounds warning in jit_disasm_helpers
  selftests/bpf: Fix out-of-bounds array access bugs reported by ASAN
  selftests/bpf: Check BPFTOOL env var in detect_bpftool_path()
  selftests/bpf: Don't override SIGSEGV handler with ASAN

 tools/bpf/resolve_btfids/Makefile             |  7 +-
 tools/bpf/resolve_btfids/main.c               | 81 ++++++++++++-------
 tools/testing/selftests/bpf/DENYLIST.asan     |  3 +
 tools/testing/selftests/bpf/Makefile          | 13 ++-
 .../selftests/bpf/benchs/bench_trigger.c      | 14 ++--
 tools/testing/selftests/bpf/bpftool_helpers.c | 13 ++-
 .../selftests/bpf/jit_disasm_helpers.c        | 18 ++---
 .../bpf/prog_tests/cgrp_local_storage.c       |  4 +-
 .../testing/selftests/bpf/prog_tests/dynptr.c |  5 +-
 .../selftests/bpf/prog_tests/fd_array.c       |  4 +-
 .../selftests/bpf/prog_tests/htab_update.c    |  1 +
 .../bpf/prog_tests/kmem_cache_iter.c          |  7 +-
 .../bpf/prog_tests/kprobe_multi_test.c        | 12 ++-
 .../selftests/bpf/prog_tests/lwt_seg6local.c  |  2 +-
 .../selftests/bpf/prog_tests/sockmap_basic.c  | 28 +++----
 .../selftests/bpf/prog_tests/sockmap_listen.c |  2 +-
 .../bpf/prog_tests/struct_ops_private_stack.c |  4 +-
 .../selftests/bpf/prog_tests/tc_opts.c        |  6 +-
 .../selftests/bpf/prog_tests/test_sysctl.c    |  3 +
 .../selftests/bpf/prog_tests/test_tc_tunnel.c |  5 +-
 .../selftests/bpf/prog_tests/test_xsk.c       | 24 +++++-
 .../bpf/prog_tests/uprobe_multi_test.c        |  6 +-
 .../selftests/bpf/prog_tests/verifier_log.c   |  2 +-
 .../selftests/bpf/prog_tests/xdp_metadata.c   |  4 +-
 tools/testing/selftests/bpf/test_progs.c      | 36 ++++++---
 tools/testing/selftests/bpf/testing_helpers.c |  1 +
 tools/testing/selftests/bpf/trace_helpers.c   | 23 +++---
 tools/testing/selftests/bpf/trace_helpers.h   | 11 ++-
 tools/testing/selftests/bpf/veristat.c        |  2 +
 29 files changed, 221 insertions(+), 120 deletions(-)
 create mode 100644 tools/testing/selftests/bpf/DENYLIST.asan

-- 
2.53.0

[PATCH bpf v3 01/15] selftests/bpf: Pass through build flags to bpftool and resolve_btfids

[Ihor Solodrai]

EXTRA_* and SAN_* build flags were not correctly propagated to bpftool
and resolve_btids when building selftests/bpf. This led to various
build errors on attempt to build with SAN_CFLAGS="-fsanitize=address",
for example.

Fix the makefiles to address this:
  - Pass SAN_CFLAGS/SAN_LDFLAGS to bpftool and resolve_btfids build
  - Propagate EXTRA_LDFLAGS to resolve_btfids link command
  - Use pkg-config to detect zlib and zstd for resolve_btfids, similar
    libelf handling

Also check for ASAN flag in selftests/bpf/Makefile for convenience.

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/bpf/resolve_btfids/Makefile    |  7 +++++--
 tools/testing/selftests/bpf/Makefile | 13 +++++++++----
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
index 1733a6e93a07..ef083602b73a 100644
--- a/tools/bpf/resolve_btfids/Makefile
+++ b/tools/bpf/resolve_btfids/Makefile
@@ -65,6 +65,9 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
 LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
 LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
 
+ZLIB_LIBS  := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz)
+ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null || echo -lzstd)
+
 HOSTCFLAGS_resolve_btfids += -g \
           -I$(srctree)/tools/include \
           -I$(srctree)/tools/include/uapi \
@@ -73,7 +76,7 @@ HOSTCFLAGS_resolve_btfids += -g \
           $(LIBELF_FLAGS) \
           -Wall -Werror
 
-LIBS = $(LIBELF_LIBS) -lz
+LIBS = $(LIBELF_LIBS) $(ZLIB_LIBS) $(ZSTD_LIBS)
 
 export srctree OUTPUT HOSTCFLAGS_resolve_btfids Q HOSTCC HOSTLD HOSTAR
 include $(srctree)/tools/build/Makefile.include
@@ -83,7 +86,7 @@ $(BINARY_IN): fixdep FORCE prepare | $(OUTPUT)
 
 $(BINARY): $(BPFOBJ) $(SUBCMDOBJ) $(BINARY_IN)
 	$(call msg,LINK,$@)
-	$(Q)$(HOSTCC) $(BINARY_IN) $(KBUILD_HOSTLDFLAGS) -o $@ $(BPFOBJ) $(SUBCMDOBJ) $(LIBS)
+	$(Q)$(HOSTCC) $(BINARY_IN) $(KBUILD_HOSTLDFLAGS) $(EXTRA_LDFLAGS) -o $@ $(BPFOBJ) $(SUBCMDOBJ) $(LIBS)
 
 clean_objects := $(wildcard $(OUTPUT)/*.o                \
                             $(OUTPUT)/.*.o.cmd           \
diff --git a/tools/testing/selftests/bpf/Makefile b/tools/testing/selftests/bpf/Makefile
index 6776158f1f3e..72a9ba41f95e 100644
--- a/tools/testing/selftests/bpf/Makefile
+++ b/tools/testing/selftests/bpf/Makefile
@@ -27,7 +27,11 @@ ifneq ($(wildcard $(GENHDR)),)
 endif
 
 BPF_GCC		?= $(shell command -v bpf-gcc;)
+ifdef ASAN
+SAN_CFLAGS 	?= -fsanitize=address -fno-omit-frame-pointer
+else
 SAN_CFLAGS	?=
+endif
 SAN_LDFLAGS	?= $(SAN_CFLAGS)
 RELEASE		?=
 OPT_FLAGS	?= $(if $(RELEASE),-O2,-O0)
@@ -326,8 +330,8 @@ $(DEFAULT_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)    \
 		    $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/bpftool
 	$(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)			       \
 		    ARCH= CROSS_COMPILE= CC="$(HOSTCC)" LD="$(HOSTLD)" 	       \
-		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(EXTRA_CFLAGS)'	       \
-		    EXTRA_LDFLAGS='$(EXTRA_LDFLAGS)'			       \
+		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(SAN_CFLAGS) $(EXTRA_CFLAGS)'	       \
+		    EXTRA_LDFLAGS='$(SAN_LDFLAGS) $(EXTRA_LDFLAGS)'			       \
 		    OUTPUT=$(HOST_BUILD_DIR)/bpftool/			       \
 		    LIBBPF_OUTPUT=$(HOST_BUILD_DIR)/libbpf/		       \
 		    LIBBPF_DESTDIR=$(HOST_SCRATCH_DIR)/			       \
@@ -338,8 +342,8 @@ $(CROSS_BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)	\
 		    $(BPFOBJ) | $(BUILD_DIR)/bpftool
 	$(Q)$(MAKE) $(submake_extras)  -C $(BPFTOOLDIR)				\
 		    ARCH=$(ARCH) CROSS_COMPILE=$(CROSS_COMPILE)			\
-		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(EXTRA_CFLAGS)'		\
-		    EXTRA_LDFLAGS='$(EXTRA_LDFLAGS)'				\
+		    EXTRA_CFLAGS='-g $(OPT_FLAGS) $(SAN_CFLAGS) $(EXTRA_CFLAGS)'	       \
+		    EXTRA_LDFLAGS='$(SAN_LDFLAGS) $(EXTRA_LDFLAGS)'			       \
 		    OUTPUT=$(BUILD_DIR)/bpftool/				\
 		    LIBBPF_OUTPUT=$(BUILD_DIR)/libbpf/				\
 		    LIBBPF_DESTDIR=$(SCRATCH_DIR)/				\
@@ -404,6 +408,7 @@ $(RESOLVE_BTFIDS): $(HOST_BPFOBJ) | $(HOST_BUILD_DIR)/resolve_btfids	\
 	$(Q)$(MAKE) $(submake_extras) -C $(TOOLSDIR)/bpf/resolve_btfids	\
 		CC="$(HOSTCC)" LD="$(HOSTLD)" AR="$(HOSTAR)" \
 		LIBBPF_INCLUDE=$(HOST_INCLUDE_DIR) \
+		EXTRA_LDFLAGS='$(SAN_LDFLAGS) $(EXTRA_LDFLAGS)' \
 		OUTPUT=$(HOST_BUILD_DIR)/resolve_btfids/ BPFOBJ=$(HOST_BPFOBJ)
 
 # Get Clang's default includes on this system, as opposed to those seen by
-- 
2.53.0

[PATCH bpf v3 02/15] resolve_btfids: Fix memory leaks reported by ASAN

[Ihor Solodrai]

Running resolve_btfids with ASAN reveals memory leaks in btf_id
handling.

- Change get_id() to use a local buffer
- Make btf_id__add() strdup the name internally
- Add btf_id__free_all() that frees all nodese of a tree
- Call the cleanup function on exit for every tree

Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/bpf/resolve_btfids/main.c | 81 ++++++++++++++++++++++-----------
 1 file changed, 54 insertions(+), 27 deletions(-)

diff --git a/tools/bpf/resolve_btfids/main.c b/tools/bpf/resolve_btfids/main.c
index ca7fcd03efb6..5208f650080f 100644
--- a/tools/bpf/resolve_btfids/main.c
+++ b/tools/bpf/resolve_btfids/main.c
@@ -226,7 +226,7 @@ static struct btf_id *btf_id__find(struct rb_root *root, const char *name)
 }
 
 static struct btf_id *__btf_id__add(struct rb_root *root,
-				    char *name,
+				    const char *name,
 				    enum btf_id_kind kind,
 				    bool unique)
 {
@@ -250,7 +250,11 @@ static struct btf_id *__btf_id__add(struct rb_root *root,
 	id = zalloc(sizeof(*id));
 	if (id) {
 		pr_debug("adding symbol %s\n", name);
-		id->name = name;
+		id->name = strdup(name);
+		if (!id->name) {
+			free(id);
+			return NULL;
+		}
 		id->kind = kind;
 		rb_link_node(&id->rb_node, parent, p);
 		rb_insert_color(&id->rb_node, root);
@@ -258,17 +262,21 @@ static struct btf_id *__btf_id__add(struct rb_root *root,
 	return id;
 }
 
-static inline struct btf_id *btf_id__add(struct rb_root *root, char *name, enum btf_id_kind kind)
+static inline struct btf_id *btf_id__add(struct rb_root *root,
+					 const char *name,
+					 enum btf_id_kind kind)
 {
 	return __btf_id__add(root, name, kind, false);
 }
 
-static inline struct btf_id *btf_id__add_unique(struct rb_root *root, char *name, enum btf_id_kind kind)
+static inline struct btf_id *btf_id__add_unique(struct rb_root *root,
+						const char *name,
+						enum btf_id_kind kind)
 {
 	return __btf_id__add(root, name, kind, true);
 }
 
-static char *get_id(const char *prefix_end)
+static int get_id(const char *prefix_end, char *buf, size_t buf_sz)
 {
 	/*
 	 * __BTF_ID__func__vfs_truncate__0
@@ -277,28 +285,28 @@ static char *get_id(const char *prefix_end)
 	 */
 	int len = strlen(prefix_end);
 	int pos = sizeof("__") - 1;
-	char *p, *id;
+	char *p;
 
 	if (pos >= len)
-		return NULL;
+		return -1;
 
-	id = strdup(prefix_end + pos);
-	if (id) {
-		/*
-		 * __BTF_ID__func__vfs_truncate__0
-		 * id =            ^
-		 *
-		 * cut the unique id part
-		 */
-		p = strrchr(id, '_');
-		p--;
-		if (*p != '_') {
-			free(id);
-			return NULL;
-		}
-		*p = '\0';
-	}
-	return id;
+	if (len - pos >= buf_sz)
+		return -1;
+
+	strcpy(buf, prefix_end + pos);
+	/*
+	 * __BTF_ID__func__vfs_truncate__0
+	 * buf =           ^
+	 *
+	 * cut the unique id part
+	 */
+	p = strrchr(buf, '_');
+	p--;
+	if (*p != '_')
+		return -1;
+	*p = '\0';
+
+	return 0;
 }
 
 static struct btf_id *add_set(struct object *obj, char *name, enum btf_id_kind kind)
@@ -335,10 +343,9 @@ static struct btf_id *add_set(struct object *obj, char *name, enum btf_id_kind k
 
 static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size)
 {
-	char *id;
+	char id[KSYM_NAME_LEN];
 
-	id = get_id(name + size);
-	if (!id) {
+	if (get_id(name + size, id, sizeof(id))) {
 		pr_err("FAILED to parse symbol name: %s\n", name);
 		return NULL;
 	}
@@ -346,6 +353,21 @@ static struct btf_id *add_symbol(struct rb_root *root, char *name, size_t size)
 	return btf_id__add(root, id, BTF_ID_KIND_SYM);
 }
 
+static void btf_id__free_all(struct rb_root *root)
+{
+	struct rb_node *next;
+	struct btf_id *id;
+
+	next = rb_first(root);
+	while (next) {
+		id = rb_entry(next, struct btf_id, rb_node);
+		next = rb_next(&id->rb_node);
+		rb_erase(&id->rb_node, root);
+		free(id->name);
+		free(id);
+	}
+}
+
 static void bswap_32_data(void *data, u32 nr_bytes)
 {
 	u32 cnt, i;
@@ -1547,6 +1569,11 @@ int main(int argc, const char **argv)
 out:
 	btf__free(obj.base_btf);
 	btf__free(obj.btf);
+	btf_id__free_all(&obj.structs);
+	btf_id__free_all(&obj.unions);
+	btf_id__free_all(&obj.typedefs);
+	btf_id__free_all(&obj.funcs);
+	btf_id__free_all(&obj.sets);
 	if (obj.efile.elf) {
 		elf_end(obj.efile.elf);
 		close(obj.efile.fd);
-- 
2.53.0

[PATCH bpf v3 03/15] selftests/bpf: Add DENYLIST.asan

[Ihor Solodrai]

Add a denylist file for tests that should be skipped when built with
userspace ASAN:

    $ make ... SAN_CFLAGS="-fsanitize=address -fno-omit-frame-pointer"

Skip the following tests:

- *arena*: userspace ASAN does not understand BPF arena maps and gets
  confused particularly when map_extra is non-zero
  - non-zero map_extra leads to mmap with MAP_FIXED, and ASAN treats
    this as an unknown memory region
- task_local_data: ASAN complains about "incorrect" aligned_alloc()
  usage, but it's intentional in the test
- uprobe_multi_test: very slow with ASAN enabled

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/testing/selftests/bpf/DENYLIST.asan | 3 +++
 1 file changed, 3 insertions(+)
 create mode 100644 tools/testing/selftests/bpf/DENYLIST.asan

diff --git a/tools/testing/selftests/bpf/DENYLIST.asan b/tools/testing/selftests/bpf/DENYLIST.asan
new file mode 100644
index 000000000000..d7fe372a2293
--- /dev/null
+++ b/tools/testing/selftests/bpf/DENYLIST.asan
@@ -0,0 +1,3 @@
+*arena*
+task_local_data
+uprobe_multi_test
-- 
2.53.0

[PATCH bpf v3 04/15] selftests/bpf: Refactor bpf_get_ksyms() trace helper

[Ihor Solodrai]

ASAN reported a memory leak in bpf_get_ksyms(): it allocates a struct
ksyms internally and never frees it.

Move struct ksyms to trace_helpers.h and return it from the
bpf_get_ksyms(), giving ownership to the caller. Add filtered_syms and
filtered_cnt fields to the ksyms to hold the filtered array of
symbols, previously returned by bpf_get_ksyms().

Fixup the call sites: kprobe_multi_test and bench_trigger.

Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 .../selftests/bpf/benchs/bench_trigger.c      | 14 ++++++-----
 .../bpf/prog_tests/kprobe_multi_test.c        | 12 ++++------
 tools/testing/selftests/bpf/trace_helpers.c   | 23 ++++++++++---------
 tools/testing/selftests/bpf/trace_helpers.h   | 11 +++++++--
 4 files changed, 34 insertions(+), 26 deletions(-)

diff --git a/tools/testing/selftests/bpf/benchs/bench_trigger.c b/tools/testing/selftests/bpf/benchs/bench_trigger.c
index aeec9edd3851..f74b313d6ae4 100644
--- a/tools/testing/selftests/bpf/benchs/bench_trigger.c
+++ b/tools/testing/selftests/bpf/benchs/bench_trigger.c
@@ -230,8 +230,8 @@ static void trigger_fentry_setup(void)
 static void attach_ksyms_all(struct bpf_program *empty, bool kretprobe)
 {
 	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
-	char **syms = NULL;
-	size_t cnt = 0;
+	struct bpf_link *link = NULL;
+	struct ksyms *ksyms = NULL;
 
 	/* Some recursive functions will be skipped in
 	 * bpf_get_ksyms -> skip_entry, as they can introduce sufficient
@@ -241,16 +241,18 @@ static void attach_ksyms_all(struct bpf_program *empty, bool kretprobe)
 	 * So, don't run the kprobe-multi-all and kretprobe-multi-all on
 	 * a debug kernel.
 	 */
-	if (bpf_get_ksyms(&syms, &cnt, true)) {
+	if (bpf_get_ksyms(&ksyms, true)) {
 		fprintf(stderr, "failed to get ksyms\n");
 		exit(1);
 	}
 
-	opts.syms = (const char **) syms;
-	opts.cnt = cnt;
+	opts.syms = (const char **)ksyms->filtered_syms;
+	opts.cnt = ksyms->filtered_cnt;
 	opts.retprobe = kretprobe;
 	/* attach empty to all the kernel functions except bpf_get_numa_node_id. */
-	if (!bpf_program__attach_kprobe_multi_opts(empty, NULL, &opts)) {
+	link = bpf_program__attach_kprobe_multi_opts(empty, NULL, &opts);
+	free_kallsyms_local(ksyms);
+	if (!link) {
 		fprintf(stderr, "failed to attach bpf_program__attach_kprobe_multi_opts to all\n");
 		exit(1);
 	}
diff --git a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
index 9caef222e528..f81dcd609ee9 100644
--- a/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/kprobe_multi_test.c
@@ -456,25 +456,23 @@ static void test_kprobe_multi_bench_attach(bool kernel)
 {
 	LIBBPF_OPTS(bpf_kprobe_multi_opts, opts);
 	struct kprobe_multi_empty *skel = NULL;
-	char **syms = NULL;
-	size_t cnt = 0;
+	struct ksyms *ksyms = NULL;
 
-	if (!ASSERT_OK(bpf_get_ksyms(&syms, &cnt, kernel), "bpf_get_ksyms"))
+	if (!ASSERT_OK(bpf_get_ksyms(&ksyms, kernel), "bpf_get_ksyms"))
 		return;
 
 	skel = kprobe_multi_empty__open_and_load();
 	if (!ASSERT_OK_PTR(skel, "kprobe_multi_empty__open_and_load"))
 		goto cleanup;
 
-	opts.syms = (const char **) syms;
-	opts.cnt = cnt;
+	opts.syms = (const char **)ksyms->filtered_syms;
+	opts.cnt = ksyms->filtered_cnt;
 
 	do_bench_test(skel, &opts);
 
 cleanup:
 	kprobe_multi_empty__destroy(skel);
-	if (syms)
-		free(syms);
+	free_kallsyms_local(ksyms);
 }
 
 static void test_kprobe_multi_bench_attach_addr(bool kernel)
diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index eeaab7013ca2..0e63daf83ed5 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -24,12 +24,6 @@
 #define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
 #define DEBUGFS_PIPE	"/sys/kernel/debug/tracing/trace_pipe"
 
-struct ksyms {
-	struct ksym *syms;
-	size_t sym_cap;
-	size_t sym_cnt;
-};
-
 static struct ksyms *ksyms;
 static pthread_mutex_t ksyms_mutex = PTHREAD_MUTEX_INITIALIZER;
 
@@ -54,6 +48,8 @@ void free_kallsyms_local(struct ksyms *ksyms)
 	if (!ksyms)
 		return;
 
+	free(ksyms->filtered_syms);
+
 	if (!ksyms->syms) {
 		free(ksyms);
 		return;
@@ -610,7 +606,7 @@ static int search_kallsyms_compare(const void *p1, const struct ksym *p2)
 	return compare_name(p1, p2->name);
 }
 
-int bpf_get_ksyms(char ***symsp, size_t *cntp, bool kernel)
+int bpf_get_ksyms(struct ksyms **ksymsp, bool kernel)
 {
 	size_t cap = 0, cnt = 0;
 	char *name = NULL, *ksym_name, **syms = NULL;
@@ -637,8 +633,10 @@ int bpf_get_ksyms(char ***symsp, size_t *cntp, bool kernel)
 	else
 		f = fopen("/sys/kernel/debug/tracing/available_filter_functions", "r");
 
-	if (!f)
+	if (!f) {
+		free_kallsyms_local(ksyms);
 		return -EINVAL;
+	}
 
 	map = hashmap__new(symbol_hash, symbol_equal, NULL);
 	if (IS_ERR(map)) {
@@ -679,15 +677,18 @@ int bpf_get_ksyms(char ***symsp, size_t *cntp, bool kernel)
 		syms[cnt++] = ksym_name;
 	}
 
-	*symsp = syms;
-	*cntp = cnt;
+	ksyms->filtered_syms = syms;
+	ksyms->filtered_cnt = cnt;
+	*ksymsp = ksyms;
 
 error:
 	free(name);
 	fclose(f);
 	hashmap__free(map);
-	if (err)
+	if (err) {
 		free(syms);
+		free_kallsyms_local(ksyms);
+	}
 	return err;
 }
 
diff --git a/tools/testing/selftests/bpf/trace_helpers.h b/tools/testing/selftests/bpf/trace_helpers.h
index a5576b2dfc26..d5bf1433675d 100644
--- a/tools/testing/selftests/bpf/trace_helpers.h
+++ b/tools/testing/selftests/bpf/trace_helpers.h
@@ -23,7 +23,14 @@ struct ksym {
 	long addr;
 	char *name;
 };
-struct ksyms;
+
+struct ksyms {
+	struct ksym *syms;
+	size_t sym_cap;
+	size_t sym_cnt;
+	char **filtered_syms;
+	size_t filtered_cnt;
+};
 
 typedef int (*ksym_cmp_t)(const void *p1, const void *p2);
 typedef int (*ksym_search_cmp_t)(const void *p1, const struct ksym *p2);
@@ -53,7 +60,7 @@ ssize_t get_rel_offset(uintptr_t addr);
 
 int read_build_id(const char *path, char *build_id, size_t size);
 
-int bpf_get_ksyms(char ***symsp, size_t *cntp, bool kernel);
+int bpf_get_ksyms(struct ksyms **ksymsp, bool kernel);
 int bpf_get_addrs(unsigned long **addrsp, size_t *cntp, bool kernel);
 
 #endif
-- 
2.53.0

[PATCH bpf v3 05/15] selftests/bpf: Fix memory leaks in tests

[Ihor Solodrai]

Fix trivial memory leaks detected by userspace ASAN:
  - htab_update: free value buffer in test_reenter_update cleanup
  - test_xsk: inline pkt_stream_replace() in testapp_stats_rx_full()
    and testapp_stats_fill_empty()
  - testing_helpers: free buffer allocated by getline() in
    parse_test_list_file

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 .../selftests/bpf/prog_tests/htab_update.c    |  1 +
 .../selftests/bpf/prog_tests/test_xsk.c       | 24 +++++++++++++++----
 tools/testing/selftests/bpf/testing_helpers.c |  1 +
 3 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/htab_update.c b/tools/testing/selftests/bpf/prog_tests/htab_update.c
index d0b405eb2966..ea1a6766fbe9 100644
--- a/tools/testing/selftests/bpf/prog_tests/htab_update.c
+++ b/tools/testing/selftests/bpf/prog_tests/htab_update.c
@@ -61,6 +61,7 @@ static void test_reenter_update(void)
 
 	ASSERT_EQ(skel->bss->update_err, -EDEADLK, "no reentrancy");
 out:
+	free(value);
 	htab_update__destroy(skel);
 }
 
diff --git a/tools/testing/selftests/bpf/prog_tests/test_xsk.c b/tools/testing/selftests/bpf/prog_tests/test_xsk.c
index bab4a31621c7..7e38ec6e656b 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_xsk.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_xsk.c
@@ -2003,9 +2003,17 @@ int testapp_stats_tx_invalid_descs(struct test_spec *test)
 
 int testapp_stats_rx_full(struct test_spec *test)
 {
-	if (pkt_stream_replace(test, DEFAULT_UMEM_BUFFERS + DEFAULT_UMEM_BUFFERS / 2, MIN_PKT_SIZE))
+	struct pkt_stream *tmp;
+
+	tmp = pkt_stream_generate(DEFAULT_UMEM_BUFFERS + DEFAULT_UMEM_BUFFERS / 2, MIN_PKT_SIZE);
+	if (!tmp)
+		return TEST_FAILURE;
+	test->ifobj_tx->xsk->pkt_stream = tmp;
+
+	tmp = pkt_stream_generate(DEFAULT_UMEM_BUFFERS, MIN_PKT_SIZE);
+	if (!tmp)
 		return TEST_FAILURE;
-	test->ifobj_rx->xsk->pkt_stream = pkt_stream_generate(DEFAULT_UMEM_BUFFERS, MIN_PKT_SIZE);
+	test->ifobj_rx->xsk->pkt_stream = tmp;
 
 	test->ifobj_rx->xsk->rxqsize = DEFAULT_UMEM_BUFFERS;
 	test->ifobj_rx->release_rx = false;
@@ -2015,9 +2023,17 @@ int testapp_stats_rx_full(struct test_spec *test)
 
 int testapp_stats_fill_empty(struct test_spec *test)
 {
-	if (pkt_stream_replace(test, DEFAULT_UMEM_BUFFERS + DEFAULT_UMEM_BUFFERS / 2, MIN_PKT_SIZE))
+	struct pkt_stream *tmp;
+
+	tmp = pkt_stream_generate(DEFAULT_UMEM_BUFFERS + DEFAULT_UMEM_BUFFERS / 2, MIN_PKT_SIZE);
+	if (!tmp)
+		return TEST_FAILURE;
+	test->ifobj_tx->xsk->pkt_stream = tmp;
+
+	tmp = pkt_stream_generate(DEFAULT_UMEM_BUFFERS, MIN_PKT_SIZE);
+	if (!tmp)
 		return TEST_FAILURE;
-	test->ifobj_rx->xsk->pkt_stream = pkt_stream_generate(DEFAULT_UMEM_BUFFERS, MIN_PKT_SIZE);
+	test->ifobj_rx->xsk->pkt_stream = tmp;
 
 	test->ifobj_rx->use_fill_ring = false;
 	test->ifobj_rx->validation_func = validate_fill_empty;
diff --git a/tools/testing/selftests/bpf/testing_helpers.c b/tools/testing/selftests/bpf/testing_helpers.c
index 16eb37e5bad6..66af0d13751a 100644
--- a/tools/testing/selftests/bpf/testing_helpers.c
+++ b/tools/testing/selftests/bpf/testing_helpers.c
@@ -212,6 +212,7 @@ int parse_test_list_file(const char *path,
 			break;
 	}
 
+	free(buf);
 	fclose(f);
 	return err;
 }
-- 
2.53.0

[PATCH bpf v3 06/15] selftests/bpf: Fix cleanup in check_fd_array_cnt__fd_array_too_big()

[Ihor Solodrai]

The Close() macro uses the passed in expression three times, which
leads to repeated execution in case it has side effects. That is,
Close(i--) would decrement i three times.

ASAN caught a stack-buffer-undeflow error at a point where this was
overlooked. Fix it.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/testing/selftests/bpf/prog_tests/fd_array.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/fd_array.c b/tools/testing/selftests/bpf/prog_tests/fd_array.c
index c534b4d5f9da..3078d8264deb 100644
--- a/tools/testing/selftests/bpf/prog_tests/fd_array.c
+++ b/tools/testing/selftests/bpf/prog_tests/fd_array.c
@@ -412,8 +412,8 @@ static void check_fd_array_cnt__fd_array_too_big(void)
 	ASSERT_EQ(prog_fd, -E2BIG, "prog should have been rejected with -E2BIG");
 
 cleanup_fds:
-	while (i > 0)
-		Close(extra_fds[--i]);
+	while (i-- > 0)
+		Close(extra_fds[i]);
 }
 
 void test_fd_array_cnt(void)
-- 
2.53.0

[PATCH bpf v3 07/15] veristat: Fix a memory leak for preset ENUMERATOR

[Ihor Solodrai]

ASAN detected a memory leak in veristat. The cleanup code handling
ENUMERATOR value missed freeing strdup-ed svalue. Fix it.

Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/testing/selftests/bpf/veristat.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/testing/selftests/bpf/veristat.c b/tools/testing/selftests/bpf/veristat.c
index 1be1e353d40a..75f85e0362f5 100644
--- a/tools/testing/selftests/bpf/veristat.c
+++ b/tools/testing/selftests/bpf/veristat.c
@@ -3378,6 +3378,8 @@ int main(int argc, char **argv)
 			}
 		}
 		free(env.presets[i].atoms);
+		if (env.presets[i].value.type == ENUMERATOR)
+			free(env.presets[i].value.svalue);
 	}
 	free(env.presets);
 	return -err;
-- 
2.53.0

[PATCH bpf v3 08/15] selftests/bpf: Fix use-after-free in xdp_metadata test

[Ihor Solodrai]

ASAN reported a use-after-free in close_xsk().

The xsk->socket internally references xsk->umem via socket->ctx->umem,
so the socket must be deleted before the umem. Fix the order of
operations in close_xsk().

Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/testing/selftests/bpf/prog_tests/xdp_metadata.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c b/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
index 19f92affc2da..5c31054ad4a4 100644
--- a/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_metadata.c
@@ -126,10 +126,10 @@ static int open_xsk(int ifindex, struct xsk *xsk)
 
 static void close_xsk(struct xsk *xsk)
 {
-	if (xsk->umem)
-		xsk_umem__delete(xsk->umem);
 	if (xsk->socket)
 		xsk_socket__delete(xsk->socket);
+	if (xsk->umem)
+		xsk_umem__delete(xsk->umem);
 	munmap(xsk->umem_area, UMEM_SIZE);
 }
 
-- 
2.53.0

[PATCH bpf v3 09/15] selftests/bpf: Fix double thread join in uprobe_multi_test

[Ihor Solodrai]

ASAN reported a "joining already joined thread" error. The
release_child() may be called multiple times for the same struct
child.

Fix by resetting child->thread to 0 after pthread_join.

Also memset(0) static child variable in test_attach_api().

Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
index 2ee17ef1dae2..56cbea280fbd 100644
--- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
+++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
@@ -62,8 +62,10 @@ static void release_child(struct child *child)
 		return;
 	close(child->go[1]);
 	close(child->go[0]);
-	if (child->thread)
+	if (child->thread) {
 		pthread_join(child->thread, NULL);
+		child->thread = 0;
+	}
 	close(child->c2p[0]);
 	close(child->c2p[1]);
 	if (child->pid > 0)
@@ -331,6 +333,8 @@ test_attach_api(const char *binary, const char *pattern, struct bpf_uprobe_multi
 {
 	static struct child child;
 
+	memset(&child, 0, sizeof(child));
+
 	/* no pid filter */
 	__test_attach_api(binary, pattern, opts, NULL);
 
-- 
2.53.0

[PATCH bpf v3 10/15] selftests/bpf: Fix resource leaks caused by missing cleanups

[Ihor Solodrai]

ASAN reported a number of resource leaks:
  - Add missing  *__destroy(skel) calls
  - Replace bpf_link__detach() with bpf_link__destroy() where appropriate
  - cgrp_local_storage: Add bpf_link__destroy() when bpf_iter_create fails
  - dynptr: Add missing bpf_object__close()

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 .../bpf/prog_tests/cgrp_local_storage.c       |  4 ++-
 .../testing/selftests/bpf/prog_tests/dynptr.c |  5 +++-
 .../selftests/bpf/prog_tests/sockmap_basic.c  | 28 +++++++++----------
 .../selftests/bpf/prog_tests/sockmap_listen.c |  2 +-
 .../bpf/prog_tests/struct_ops_private_stack.c |  4 +--
 .../selftests/bpf/prog_tests/tc_opts.c        |  6 ++--
 .../selftests/bpf/prog_tests/test_tc_tunnel.c |  5 +++-
 7 files changed, 29 insertions(+), 25 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c b/tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c
index 9015e2c2ab12..478a77cb67e6 100644
--- a/tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c
+++ b/tools/testing/selftests/bpf/prog_tests/cgrp_local_storage.c
@@ -202,7 +202,7 @@ static void test_cgroup_iter_sleepable(int cgroup_fd, __u64 cgroup_id)
 
 	iter_fd = bpf_iter_create(bpf_link__fd(link));
 	if (!ASSERT_GE(iter_fd, 0, "iter_create"))
-		goto out;
+		goto out_link;
 
 	/* trigger the program run */
 	(void)read(iter_fd, buf, sizeof(buf));
@@ -210,6 +210,8 @@ static void test_cgroup_iter_sleepable(int cgroup_fd, __u64 cgroup_id)
 	ASSERT_EQ(skel->bss->cgroup_id, cgroup_id, "cgroup_id");
 
 	close(iter_fd);
+out_link:
+	bpf_link__destroy(link);
 out:
 	cgrp_ls_sleepable__destroy(skel);
 }
diff --git a/tools/testing/selftests/bpf/prog_tests/dynptr.c b/tools/testing/selftests/bpf/prog_tests/dynptr.c
index b9f86cb91e81..5fda11590708 100644
--- a/tools/testing/selftests/bpf/prog_tests/dynptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/dynptr.c
@@ -137,11 +137,14 @@ static void verify_success(const char *prog_name, enum test_setup_type setup_typ
 		);
 
 		link = bpf_program__attach(prog);
-		if (!ASSERT_OK_PTR(link, "bpf_program__attach"))
+		if (!ASSERT_OK_PTR(link, "bpf_program__attach")) {
+			bpf_object__close(obj);
 			goto cleanup;
+		}
 
 		err = bpf_prog_test_run_opts(aux_prog_fd, &topts);
 		bpf_link__destroy(link);
+		bpf_object__close(obj);
 
 		if (!ASSERT_OK(err, "test_run"))
 			goto cleanup;
diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
index 256707e7d20d..dd3c757859f6 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_basic.c
@@ -204,7 +204,7 @@ static void test_skmsg_helpers_with_link(enum bpf_map_type map_type)
 	/* Fail since bpf_link for the same prog type has been created. */
 	link2 = bpf_program__attach_sockmap(prog_clone, map);
 	if (!ASSERT_ERR_PTR(link2, "bpf_program__attach_sockmap")) {
-		bpf_link__detach(link2);
+		bpf_link__destroy(link2);
 		goto out;
 	}
 
@@ -230,7 +230,7 @@ static void test_skmsg_helpers_with_link(enum bpf_map_type map_type)
 	if (!ASSERT_OK(err, "bpf_link_update"))
 		goto out;
 out:
-	bpf_link__detach(link);
+	bpf_link__destroy(link);
 	test_skmsg_load_helpers__destroy(skel);
 }
 
@@ -417,7 +417,7 @@ static void test_sockmap_skb_verdict_attach_with_link(void)
 	if (!ASSERT_OK_PTR(link, "bpf_program__attach_sockmap"))
 		goto out;
 
-	bpf_link__detach(link);
+	bpf_link__destroy(link);
 
 	err = bpf_prog_attach(bpf_program__fd(prog), map, BPF_SK_SKB_STREAM_VERDICT, 0);
 	if (!ASSERT_OK(err, "bpf_prog_attach"))
@@ -426,7 +426,7 @@ static void test_sockmap_skb_verdict_attach_with_link(void)
 	/* Fail since attaching with the same prog/map has been done. */
 	link = bpf_program__attach_sockmap(prog, map);
 	if (!ASSERT_ERR_PTR(link, "bpf_program__attach_sockmap"))
-		bpf_link__detach(link);
+		bpf_link__destroy(link);
 
 	err = bpf_prog_detach2(bpf_program__fd(prog), map, BPF_SK_SKB_STREAM_VERDICT);
 	if (!ASSERT_OK(err, "bpf_prog_detach2"))
@@ -747,13 +747,13 @@ static void test_sockmap_skb_verdict_peek_with_link(void)
 	test_sockmap_skb_verdict_peek_helper(map);
 	ASSERT_EQ(pass->bss->clone_called, 1, "clone_called");
 out:
-	bpf_link__detach(link);
+	bpf_link__destroy(link);
 	test_sockmap_pass_prog__destroy(pass);
 }
 
 static void test_sockmap_unconnected_unix(void)
 {
-	int err, map, stream = 0, dgram = 0, zero = 0;
+	int err, map, stream = -1, dgram = -1, zero = 0;
 	struct test_sockmap_pass_prog *skel;
 
 	skel = test_sockmap_pass_prog__open_and_load();
@@ -764,22 +764,22 @@ static void test_sockmap_unconnected_unix(void)
 
 	stream = xsocket(AF_UNIX, SOCK_STREAM, 0);
 	if (stream < 0)
-		return;
+		goto out;
 
 	dgram = xsocket(AF_UNIX, SOCK_DGRAM, 0);
-	if (dgram < 0) {
-		close(stream);
-		return;
-	}
+	if (dgram < 0)
+		goto out;
 
 	err = bpf_map_update_elem(map, &zero, &stream, BPF_ANY);
-	ASSERT_ERR(err, "bpf_map_update_elem(stream)");
+	if (!ASSERT_ERR(err, "bpf_map_update_elem(stream)"))
+		goto out;
 
 	err = bpf_map_update_elem(map, &zero, &dgram, BPF_ANY);
 	ASSERT_OK(err, "bpf_map_update_elem(dgram)");
-
+out:
 	close(stream);
 	close(dgram);
+	test_sockmap_pass_prog__destroy(skel);
 }
 
 static void test_sockmap_many_socket(void)
@@ -1027,7 +1027,7 @@ static void test_sockmap_skb_verdict_vsock_poll(void)
 	if (xrecv_nonblock(conn, &buf, 1, 0) != 1)
 		FAIL("xrecv_nonblock");
 detach:
-	bpf_link__detach(link);
+	bpf_link__destroy(link);
 close:
 	xclose(conn);
 	xclose(peer);
diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
index f1bdccc7e4e7..cc0c68bab907 100644
--- a/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
+++ b/tools/testing/selftests/bpf/prog_tests/sockmap_listen.c
@@ -899,7 +899,7 @@ static void test_msg_redir_to_listening_with_link(struct test_sockmap_listen *sk
 
 	redir_to_listening(family, sotype, sock_map, verdict_map, REDIR_EGRESS);
 
-	bpf_link__detach(link);
+	bpf_link__destroy(link);
 }
 
 static void redir_partial(int family, int sotype, int sock_map, int parser_map)
diff --git a/tools/testing/selftests/bpf/prog_tests/struct_ops_private_stack.c b/tools/testing/selftests/bpf/prog_tests/struct_ops_private_stack.c
index 4006879ca3fe..d42123a0fb16 100644
--- a/tools/testing/selftests/bpf/prog_tests/struct_ops_private_stack.c
+++ b/tools/testing/selftests/bpf/prog_tests/struct_ops_private_stack.c
@@ -54,9 +54,7 @@ static void test_private_stack_fail(void)
 	}
 
 	err = struct_ops_private_stack_fail__load(skel);
-	if (!ASSERT_ERR(err, "struct_ops_private_stack_fail__load"))
-		goto cleanup;
-	return;
+	ASSERT_ERR(err, "struct_ops_private_stack_fail__load");
 
 cleanup:
 	struct_ops_private_stack_fail__destroy(skel);
diff --git a/tools/testing/selftests/bpf/prog_tests/tc_opts.c b/tools/testing/selftests/bpf/prog_tests/tc_opts.c
index dd7a138d8c3d..2955750ddada 100644
--- a/tools/testing/selftests/bpf/prog_tests/tc_opts.c
+++ b/tools/testing/selftests/bpf/prog_tests/tc_opts.c
@@ -1360,10 +1360,8 @@ static void test_tc_opts_dev_cleanup_target(int target)
 
 	assert_mprog_count_ifindex(ifindex, target, 4);
 
-	ASSERT_OK(system("ip link del dev tcx_opts1"), "del veth");
-	ASSERT_EQ(if_nametoindex("tcx_opts1"), 0, "dev1_removed");
-	ASSERT_EQ(if_nametoindex("tcx_opts2"), 0, "dev2_removed");
-	return;
+	goto cleanup;
+
 cleanup3:
 	err = bpf_prog_detach_opts(fd3, loopback, target, &optd);
 	ASSERT_OK(err, "prog_detach");
diff --git a/tools/testing/selftests/bpf/prog_tests/test_tc_tunnel.c b/tools/testing/selftests/bpf/prog_tests/test_tc_tunnel.c
index 0fe0a8f62486..7fc4d7dd70ef 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_tc_tunnel.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_tc_tunnel.c
@@ -699,7 +699,7 @@ void test_tc_tunnel(void)
 		return;
 
 	if (!ASSERT_OK(setup(), "global setup"))
-		return;
+		goto out;
 
 	for (i = 0; i < ARRAY_SIZE(subtests_cfg); i++) {
 		cfg = &subtests_cfg[i];
@@ -711,4 +711,7 @@ void test_tc_tunnel(void)
 		subtest_cleanup(cfg);
 	}
 	cleanup();
+
+out:
+	test_tc_tunnel__destroy(skel);
 }
-- 
2.53.0

[PATCH bpf v3 11/15] selftests/bpf: Free bpf_object in test_sysctl

[Ihor Solodrai]

ASAN reported a resource leak due to the bpf_object not being tracked
in test_sysctl. Add obj field to struct sysctl_test to properly clean
it up.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/testing/selftests/bpf/prog_tests/test_sysctl.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/test_sysctl.c b/tools/testing/selftests/bpf/prog_tests/test_sysctl.c
index 273dd41ca09e..2a1ff821bc97 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_sysctl.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_sysctl.c
@@ -27,6 +27,7 @@ struct sysctl_test {
 		OP_EPERM,
 		SUCCESS,
 	} result;
+	struct bpf_object *obj;
 };
 
 static struct sysctl_test tests[] = {
@@ -1471,6 +1472,7 @@ static int load_sysctl_prog_file(struct sysctl_test *test)
 		return -1;
 	}
 
+	test->obj = obj;
 	return prog_fd;
 }
 
@@ -1573,6 +1575,7 @@ static int run_test_case(int cgfd, struct sysctl_test *test)
 	/* Detaching w/o checking return code: best effort attempt. */
 	if (progfd != -1)
 		bpf_prog_detach(cgfd, atype);
+	bpf_object__close(test->obj);
 	close(progfd);
 	printf("[%s]\n", err ? "FAIL" : "PASS");
 	return err;
-- 
2.53.0

[PATCH bpf v3 12/15] selftests/bpf: Fix array bounds warning in jit_disasm_helpers

[Ihor Solodrai]

Compiler cannot infer upper bound for labels.cnt and warns about
potential buffer overflow in snprintf. Add an explicit bounds
check (... && i < MAX_LOCAL_LABELS) in the loop condition to fix the
warning.

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 .../testing/selftests/bpf/jit_disasm_helpers.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/bpf/jit_disasm_helpers.c b/tools/testing/selftests/bpf/jit_disasm_helpers.c
index febd6b12e372..364c557c5115 100644
--- a/tools/testing/selftests/bpf/jit_disasm_helpers.c
+++ b/tools/testing/selftests/bpf/jit_disasm_helpers.c
@@ -122,15 +122,15 @@ static int disasm_one_func(FILE *text_out, uint8_t *image, __u32 len)
 		pc += cnt;
 	}
 	qsort(labels.pcs, labels.cnt, sizeof(*labels.pcs), cmp_u32);
-	for (i = 0; i < labels.cnt; ++i)
-		/* gcc is unable to infer upper bound for labels.cnt and assumes
-		 * it to be U32_MAX. U32_MAX takes 10 decimal digits.
-		 * snprintf below prints into labels.names[*],
-		 * which has space only for two digits and a letter.
-		 * To avoid truncation warning use (i % MAX_LOCAL_LABELS),
-		 * which informs gcc about printed value upper bound.
-		 */
-		snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i % MAX_LOCAL_LABELS);
+	/* gcc is unable to infer upper bound for labels.cnt and
+	 * assumes it to be U32_MAX. U32_MAX takes 10 decimal digits.
+	 * snprintf below prints into labels.names[*], which has space
+	 * only for two digits and a letter.  To avoid truncation
+	 * warning use (i < MAX_LOCAL_LABELS), which informs gcc about
+	 * printed value upper bound.
+	 */
+	for (i = 0; i < labels.cnt && i < MAX_LOCAL_LABELS; ++i)
+		snprintf(labels.names[i], sizeof(labels.names[i]), "L%d", i);
 
 	/* now print with labels */
 	labels.print_phase = true;
-- 
2.53.0

[PATCH bpf v3 13/15] selftests/bpf: Fix out-of-bounds array access bugs reported by ASAN

[Ihor Solodrai]

- kmem_cache_iter: remove unnecessary debug output
- lwt_seg6local: change the type of foobar to char[]
  - the sizeof(foobar) returned the pointer size and not a string
    length as intended
- verifier_log: increase prog_name buffer size in verif_log_subtest()
  - compiler has a conservative estimate of fixed_log_sz value, making
    ASAN complain on snprint() call

Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c | 7 ++-----
 tools/testing/selftests/bpf/prog_tests/lwt_seg6local.c   | 2 +-
 tools/testing/selftests/bpf/prog_tests/verifier_log.c    | 2 +-
 3 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c
index 6e35e13c2022..399fe9103f83 100644
--- a/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c
+++ b/tools/testing/selftests/bpf/prog_tests/kmem_cache_iter.c
@@ -104,11 +104,8 @@ void test_kmem_cache_iter(void)
 	if (!ASSERT_GE(iter_fd, 0, "iter_create"))
 		goto destroy;
 
-	memset(buf, 0, sizeof(buf));
-	while (read(iter_fd, buf, sizeof(buf)) > 0) {
-		/* Read out all contents */
-		printf("%s", buf);
-	}
+	while (read(iter_fd, buf, sizeof(buf)) > 0)
+		; /* Read out all contents */
 
 	/* Next reads should return 0 */
 	ASSERT_EQ(read(iter_fd, buf, sizeof(buf)), 0, "read");
diff --git a/tools/testing/selftests/bpf/prog_tests/lwt_seg6local.c b/tools/testing/selftests/bpf/prog_tests/lwt_seg6local.c
index 3bc730b7c7fa..1b25d5c5f8fb 100644
--- a/tools/testing/selftests/bpf/prog_tests/lwt_seg6local.c
+++ b/tools/testing/selftests/bpf/prog_tests/lwt_seg6local.c
@@ -117,7 +117,7 @@ void test_lwt_seg6local(void)
 	const char *ns1 = NETNS_BASE "1";
 	const char *ns6 = NETNS_BASE "6";
 	struct nstoken *nstoken = NULL;
-	const char *foobar = "foobar";
+	const char foobar[] = "foobar";
 	ssize_t bytes;
 	int sfd, cfd;
 	char buf[7];
diff --git a/tools/testing/selftests/bpf/prog_tests/verifier_log.c b/tools/testing/selftests/bpf/prog_tests/verifier_log.c
index 8337c6bc5b95..aaa2854974c0 100644
--- a/tools/testing/selftests/bpf/prog_tests/verifier_log.c
+++ b/tools/testing/selftests/bpf/prog_tests/verifier_log.c
@@ -47,7 +47,7 @@ static int load_prog(struct bpf_prog_load_opts *opts, bool expect_load_error)
 static void verif_log_subtest(const char *name, bool expect_load_error, int log_level)
 {
 	LIBBPF_OPTS(bpf_prog_load_opts, opts);
-	char *exp_log, prog_name[16], op_name[32];
+	char *exp_log, prog_name[24], op_name[32];
 	struct test_log_buf *skel;
 	struct bpf_program *prog;
 	size_t fixed_log_sz;
-- 
2.53.0

[PATCH bpf v3 14/15] selftests/bpf: Check BPFTOOL env var in detect_bpftool_path()

[Ihor Solodrai]

The bpftool_maps_access and bpftool_metadata tests may fail on BPF CI
with "command not found", depending on a workflow.
This happens because detect_bpftool_path() only checks two hardcoded
relative paths:
  - ./tools/sbin/bpftool
  - ../tools/sbin/bpftool

Add support for a BPFTOOL environment variable that allows specifying
the exact path to the bpftool binary.

Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/testing/selftests/bpf/bpftool_helpers.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/bpftool_helpers.c b/tools/testing/selftests/bpf/bpftool_helpers.c
index c99776b03f52..774a22d624e7 100644
--- a/tools/testing/selftests/bpf/bpftool_helpers.c
+++ b/tools/testing/selftests/bpf/bpftool_helpers.c
@@ -14,6 +14,17 @@
 static int detect_bpftool_path(char *buffer, size_t size)
 {
 	char tmp[BPFTOOL_PATH_MAX_LEN];
+	const char *env_path;
+
+	/* First, check if BPFTOOL environment variable is set */
+	env_path = getenv("BPFTOOL");
+	if (env_path && access(env_path, X_OK) == 0) {
+		strscpy(buffer, env_path, size);
+		return 0;
+	} else if (env_path) {
+		fprintf(stderr, "bpftool '%s' doesn't exist or is not executable\n", env_path);
+		return 1;
+	}
 
 	/* Check default bpftool location (will work if we are running the
 	 * default flavor of test_progs)
@@ -33,7 +44,7 @@ static int detect_bpftool_path(char *buffer, size_t size)
 		return 0;
 	}
 
-	/* Failed to find bpftool binary */
+	fprintf(stderr, "Failed to detect bpftool path, use BPFTOOL env var to override\n");
 	return 1;
 }
 
-- 
2.53.0

[PATCH bpf v3 15/15] selftests/bpf: Don't override SIGSEGV handler with ASAN

[Ihor Solodrai]

test_progs has custom SIGSEGV handler, which interferes with the
address sanitizer [1]. Add an #ifndef to avoid this.

Additionally, declare an __asan_on_error() to dump the test logs in
the same way it happens in the custom SIGSEGV handler.

[1] https://lore.kernel.org/bpf/73d832948b01dbc0ebc60d85574bdf8537f3a810.camel@gmail.com/

Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
---
 tools/testing/selftests/bpf/test_progs.c | 36 +++++++++++++++++-------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
index d1418ec1f351..0929f4a7bda4 100644
--- a/tools/testing/selftests/bpf/test_progs.c
+++ b/tools/testing/selftests/bpf/test_progs.c
@@ -1261,14 +1261,8 @@ int get_bpf_max_tramp_links(void)
 	return ret;
 }
 
-#define MAX_BACKTRACE_SZ 128
-void crash_handler(int signum)
+static void dump_crash_log(void)
 {
-	void *bt[MAX_BACKTRACE_SZ];
-	size_t sz;
-
-	sz = backtrace(bt, ARRAY_SIZE(bt));
-
 	fflush(stdout);
 	stdout = env.stdout_saved;
 	stderr = env.stderr_saved;
@@ -1277,12 +1271,32 @@ void crash_handler(int signum)
 		env.test_state->error_cnt++;
 		dump_test_log(env.test, env.test_state, true, false, NULL);
 	}
+}
+
+#define MAX_BACKTRACE_SZ 128
+
+void crash_handler(int signum)
+{
+	void *bt[MAX_BACKTRACE_SZ];
+	size_t sz;
+
+	sz = backtrace(bt, ARRAY_SIZE(bt));
+
+	dump_crash_log();
+
 	if (env.worker_id != -1)
 		fprintf(stderr, "[%d]: ", env.worker_id);
 	fprintf(stderr, "Caught signal #%d!\nStack trace:\n", signum);
 	backtrace_symbols_fd(bt, sz, STDERR_FILENO);
 }
 
+#ifdef __SANITIZE_ADDRESS__
+void __asan_on_error(void)
+{
+	dump_crash_log();
+}
+#endif
+
 void hexdump(const char *prefix, const void *buf, size_t len)
 {
 	for (int i = 0; i < len; i++) {
@@ -1944,13 +1958,15 @@ int main(int argc, char **argv)
 		.parser = parse_arg,
 		.doc = argp_program_doc,
 	};
+	int err, i;
+
+#ifndef __SANITIZE_ADDRESS__
 	struct sigaction sigact = {
 		.sa_handler = crash_handler,
 		.sa_flags = SA_RESETHAND,
-		};
-	int err, i;
-
+	};
 	sigaction(SIGSEGV, &sigact, NULL);
+#endif
 
 	env.stdout_saved = stdout;
 	env.stderr_saved = stderr;
-- 
2.53.0

Re: [PATCH bpf v3 01/15] selftests/bpf: Pass through build flags to bpftool and resolve_btfids

[bot+bpf-ci]

[-- Attachment #1: Type: text/plain, Size: 2174 bytes --]

> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
> index 1733a6e93a07..ef083602b73a 100644
> --- a/tools/bpf/resolve_btfids/Makefile
> +++ b/tools/bpf/resolve_btfids/Makefile
> @@ -65,6 +65,9 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
>  LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
>  LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
>
> +ZLIB_LIBS  := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz)
> +ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null || echo -lzstd)

The "|| echo -lzstd" fallback makes zstd an unconditional link
dependency. On systems where libzstd-dev is not installed, pkg-config
fails and the fallback provides -lzstd, but the linker cannot find the
library and the build fails.

bpftool handles the same transitive dependency conditionally via a
feature test:

tools/bpf/bpftool/Makefile:
    ifeq ($(feature-libelf-zstd),1)
    LIBS += -lzstd
    LIBS_BOOTSTRAP += -lzstd
    endif

Would it be safer to drop the fallback here so ZSTD_LIBS is empty
when zstd is not available?

    ZSTD_LIBS := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null)

This would still link zstd when present (needed for the static linking
case where libelf.a pulls in ZSTD symbols from elf_compress.o), but
avoid breaking dynamic builds on systems without libzstd-dev.

[ ... ]


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/22243753316

AI-authorship-score: low
AI-authorship-explanation: Human-characteristic typo in commit message, natural lore discussion with incremental debugging, and standard Makefile pattern reuse all indicate human authorship.
issues-found: 1
issue-severity-score: low
issue-severity-explanation: Unconditional zstd link fallback in resolve_btfids Makefile can break builds on systems without libzstd-dev, but the affected scenario is narrow and limited to the selftests build system.

Re: [PATCH bpf v3 15/15] selftests/bpf: Don't override SIGSEGV handler with ASAN

[Eduard Zingerman]

On Fri, 2026-02-20 at 14:26 -0800, Ihor Solodrai wrote:
> test_progs has custom SIGSEGV handler, which interferes with the
> address sanitizer [1]. Add an #ifndef to avoid this.
> 
> Additionally, declare an __asan_on_error() to dump the test logs in
> the same way it happens in the custom SIGSEGV handler.
> 
> [1] https://lore.kernel.org/bpf/73d832948b01dbc0ebc60d85574bdf8537f3a810.camel@gmail.com/
> 
> Acked-by: Mykyta Yatsenko <yatsenko@meta.com>
> Signed-off-by: Ihor Solodrai <ihor.solodrai@linux.dev>
> ---

Acked-by: Eduard Zingerman <eddyz87@gmail.com>

[...]

Re: [PATCH bpf v3 01/15] selftests/bpf: Pass through build flags to bpftool and resolve_btfids

[Ihor Solodrai]

On 2/20/26 2:57 PM, bot+bpf-ci@kernel.org wrote:
>> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
>> index 1733a6e93a07..ef083602b73a 100644
>> --- a/tools/bpf/resolve_btfids/Makefile
>> +++ b/tools/bpf/resolve_btfids/Makefile
>> @@ -65,6 +65,9 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
>>  LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
>>  LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
>>
>> +ZLIB_LIBS  := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz)
>> +ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null || echo -lzstd)
> 
> The "|| echo -lzstd" fallback makes zstd an unconditional link
> dependency. On systems where libzstd-dev is not installed, pkg-config
> fails and the fallback provides -lzstd, but the linker cannot find the
> library and the build fails.
> 
> bpftool handles the same transitive dependency conditionally via a
> feature test:
> 
> tools/bpf/bpftool/Makefile:
>     ifeq ($(feature-libelf-zstd),1)
>     LIBS += -lzstd
>     LIBS_BOOTSTRAP += -lzstd
>     endif
> 
> Would it be safer to drop the fallback here so ZSTD_LIBS is empty
> when zstd is not available?
> 
>     ZSTD_LIBS := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null)
> 
> This would still link zstd when present (needed for the static linking
> case where libelf.a pulls in ZSTD symbols from elf_compress.o), but
> avoid breaking dynamic builds on systems without libzstd-dev.

I tried to reproduce the situation like follows:

  $ git remote -v
  origin	git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git (fetch)
  origin	git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git (push)

  $ git log --oneline -n1
  8bf22c33e7a1 (HEAD -> master, origin/master, origin/HEAD) Merge tag 'net-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

  $ b4 shazam 20260220182011.802116-1-ihor.solodrai@linux.dev   # apply strscpy series
  $ b4 shazam 20260220222604.1155148-1-ihor.solodrai@linux.dev  # apply ASAN series

  $ podman pull debian:latest
  $ podman run -it --rm -v $(pwd):/linux debian:latest /bin/bash

  # in the container
  $ apt update -y && apt install -y make gcc python3 libelf-dev
  # note: no libzstd-dev

  $ cd /linux/tools/bpf/resolve_btfids/
  $ make -j8
  # build is successful

  $ ldd resolve_btfids
	linux-vdso.so.1 (0x00007f3eecc81000)
	libelf.so.1 => /lib/x86_64-linux-gnu/libelf.so.1 (0x00007f3eecbe2000)
	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f3eecbc2000)
	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3eec9cd000)
	libzstd.so.1 => /lib/x86_64-linux-gnu/libzstd.so.1 (0x00007f3eec903000)
	/lib64/ld-linux-x86-64.so.2 (0x00007f3eecc83000)


So, while AI may be technically correct that the build will fail if
libelf is installed and libzstd is not, it seems a far-fetched
situation, given that libelf depends on libzstd.

I think we can leave the default -lzstd to have an explicit
dependency in the Makefile.


> 
> [ ... ]
> 
> 
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
> 
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/22243753316
> 
> AI-authorship-score: low
> AI-authorship-explanation: Human-characteristic typo in commit message, natural lore discussion with incremental debugging, and standard Makefile pattern reuse all indicate human authorship.
> issues-found: 1
> issue-severity-score: low
> issue-severity-explanation: Unconditional zstd link fallback in resolve_btfids Makefile can break builds on systems without libzstd-dev, but the affected scenario is narrow and limited to the selftests build system.

Re: [PATCH bpf v3 01/15] selftests/bpf: Pass through build flags to bpftool and resolve_btfids

[Vitaly Chikunov]

Ihor,

On Fri, Feb 20, 2026 at 08:23:51PM -0800, Ihor Solodrai wrote:
> 
> 
> On 2/20/26 2:57 PM, bot+bpf-ci@kernel.org wrote:
> >> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
> >> index 1733a6e93a07..ef083602b73a 100644
> >> --- a/tools/bpf/resolve_btfids/Makefile
> >> +++ b/tools/bpf/resolve_btfids/Makefile
> >> @@ -65,6 +65,9 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
> >>  LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
> >>  LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
> >>
> >> +ZLIB_LIBS  := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz)
> >> +ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null || echo -lzstd)
> > 
> > The "|| echo -lzstd" fallback makes zstd an unconditional link
> > dependency. On systems where libzstd-dev is not installed, pkg-config
> > fails and the fallback provides -lzstd, but the linker cannot find the
> > library and the build fails.
> > 
> > bpftool handles the same transitive dependency conditionally via a
> > feature test:
> > 
> > tools/bpf/bpftool/Makefile:
> >     ifeq ($(feature-libelf-zstd),1)
> >     LIBS += -lzstd
> >     LIBS_BOOTSTRAP += -lzstd
> >     endif
> > 
> > Would it be safer to drop the fallback here so ZSTD_LIBS is empty
> > when zstd is not available?
> > 
> >     ZSTD_LIBS := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null)
> > 
> > This would still link zstd when present (needed for the static linking
> > case where libelf.a pulls in ZSTD symbols from elf_compress.o), but
> > avoid breaking dynamic builds on systems without libzstd-dev.
> 
> I tried to reproduce the situation like follows:
> 
>   $ git remote -v
>   origin	git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git (fetch)
>   origin	git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git (push)
> 
>   $ git log --oneline -n1
>   8bf22c33e7a1 (HEAD -> master, origin/master, origin/HEAD) Merge tag 'net-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
> 
>   $ b4 shazam 20260220182011.802116-1-ihor.solodrai@linux.dev   # apply strscpy series
>   $ b4 shazam 20260220222604.1155148-1-ihor.solodrai@linux.dev  # apply ASAN series
> 
>   $ podman pull debian:latest
>   $ podman run -it --rm -v $(pwd):/linux debian:latest /bin/bash
> 
>   # in the container
>   $ apt update -y && apt install -y make gcc python3 libelf-dev
>   # note: no libzstd-dev
> 
>   $ cd /linux/tools/bpf/resolve_btfids/
>   $ make -j8
>   # build is successful
> 
>   $ ldd resolve_btfids
> 	linux-vdso.so.1 (0x00007f3eecc81000)
> 	libelf.so.1 => /lib/x86_64-linux-gnu/libelf.so.1 (0x00007f3eecbe2000)
> 	libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007f3eecbc2000)
> 	libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f3eec9cd000)
> 	libzstd.so.1 => /lib/x86_64-linux-gnu/libzstd.so.1 (0x00007f3eec903000)
> 	/lib64/ld-linux-x86-64.so.2 (0x00007f3eecc83000)
> 
> 
> So, while AI may be technically correct that the build will fail if
> libelf is installed and libzstd is not, it seems a far-fetched
> situation, given that libelf depends on libzstd.

This is not far-fetched, and we have build failure for v7.0-rc2 due to
this.

  ld: cannot find -lzstd: No such file or directory

Even though libelf is linked with libzstd, this does not imply
libzstd-devel (with headers and so library) is there when building.

Thanks,

> 
> I think we can leave the default -lzstd to have an explicit
> dependency in the Makefile.
> 
> 
> > 
> > [ ... ]
> > 
> > 
> > ---
> > AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> > See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
> > 
> > CI run summary: https://github.com/kernel-patches/bpf/actions/runs/22243753316
> > 
> > AI-authorship-score: low
> > AI-authorship-explanation: Human-characteristic typo in commit message, natural lore discussion with incremental debugging, and standard Makefile pattern reuse all indicate human authorship.
> > issues-found: 1
> > issue-severity-score: low
> > issue-severity-explanation: Unconditional zstd link fallback in resolve_btfids Makefile can break builds on systems without libzstd-dev, but the affected scenario is narrow and limited to the selftests build system.
> 

Re: [PATCH bpf v3 01/15] selftests/bpf: Pass through build flags to bpftool and resolve_btfids

[Ihor Solodrai]

On 3/2/26 7:22 AM, Vitaly Chikunov wrote:
> Ihor,
> 
> On Fri, Feb 20, 2026 at 08:23:51PM -0800, Ihor Solodrai wrote:
>>
>>
>> On 2/20/26 2:57 PM, bot+bpf-ci@kernel.org wrote:
>>>> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
>>>> index 1733a6e93a07..ef083602b73a 100644
>>>> --- a/tools/bpf/resolve_btfids/Makefile
>>>> +++ b/tools/bpf/resolve_btfids/Makefile
>>>> @@ -65,6 +65,9 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
>>>>  LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
>>>>  LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
>>>>
>>>> +ZLIB_LIBS  := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz)
>>>> +ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null || echo -lzstd)
>>>
>>> The "|| echo -lzstd" fallback makes zstd an unconditional link
>>> dependency. On systems where libzstd-dev is not installed, pkg-config
>>> fails and the fallback provides -lzstd, but the linker cannot find the
>>> library and the build fails.
>>>
>>> bpftool handles the same transitive dependency conditionally via a
>>> feature test:
>>>
>>> tools/bpf/bpftool/Makefile:
>>>     ifeq ($(feature-libelf-zstd),1)
>>>     LIBS += -lzstd
>>>     LIBS_BOOTSTRAP += -lzstd
>>>     endif
>>>
>>> Would it be safer to drop the fallback here so ZSTD_LIBS is empty
>>> when zstd is not available?
>>>
>>>     ZSTD_LIBS := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null)
>>>
>>> This would still link zstd when present (needed for the static linking
>>> case where libelf.a pulls in ZSTD symbols from elf_compress.o), but
>>> avoid breaking dynamic builds on systems without libzstd-dev.
>>
>> [...]
>>
>>
>> So, while AI may be technically correct that the build will fail if
>> libelf is installed and libzstd is not, it seems a far-fetched
>> situation, given that libelf depends on libzstd.
> 
> This is not far-fetched, and we have build failure for v7.0-rc2 due to
> this.
> 
>   ld: cannot find -lzstd: No such file or directory
> 
> Even though libelf is linked with libzstd, this does not imply
> libzstd-devel (with headers and so library) is there when building.

Does AI's suggestion make sense in your case then?
That is, make ZSTD_LIBS empty in case pkg-config didn't find libzstd?

I'm happy to fix this, the build shouldn't fail unless it must.

But I am curious how and why an environment building Linux with BTF
(requiring build and run of resolve_btfids), which needs libelf-dev
and presumably its dependencies, would exclude/avoid installing
libzstd-dev?

Thanks.

> 
> Thanks,
> 
>>
>> I think we can leave the default -lzstd to have an explicit
>> dependency in the Makefile.
>>
>>
>>>
>>> [ ... ]

Re: [PATCH bpf v3 01/15] selftests/bpf: Pass through build flags to bpftool and resolve_btfids

[Vitaly Chikunov]

Ihor,

On Mon, Mar 02, 2026 at 10:01:59AM -0800, Ihor Solodrai wrote:
> On 3/2/26 7:22 AM, Vitaly Chikunov wrote:
> > On Fri, Feb 20, 2026 at 08:23:51PM -0800, Ihor Solodrai wrote:
> >> On 2/20/26 2:57 PM, bot+bpf-ci@kernel.org wrote:
> >>>> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
> >>>> index 1733a6e93a07..ef083602b73a 100644
> >>>> --- a/tools/bpf/resolve_btfids/Makefile
> >>>> +++ b/tools/bpf/resolve_btfids/Makefile
> >>>> @@ -65,6 +65,9 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
> >>>>  LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
> >>>>  LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
> >>>>
> >>>> +ZLIB_LIBS  := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz)
> >>>> +ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null || echo -lzstd)
> >>>
> >>> The "|| echo -lzstd" fallback makes zstd an unconditional link
> >>> dependency. On systems where libzstd-dev is not installed, pkg-config
> >>> fails and the fallback provides -lzstd, but the linker cannot find the
> >>> library and the build fails.
> >>>
> >>> bpftool handles the same transitive dependency conditionally via a
> >>> feature test:
> >>>
> >>> tools/bpf/bpftool/Makefile:
> >>>     ifeq ($(feature-libelf-zstd),1)
> >>>     LIBS += -lzstd
> >>>     LIBS_BOOTSTRAP += -lzstd
> >>>     endif
> >>>
> >>> Would it be safer to drop the fallback here so ZSTD_LIBS is empty
> >>> when zstd is not available?
> >>>
> >>>     ZSTD_LIBS := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null)
> >>>
> >>> This would still link zstd when present (needed for the static linking
> >>> case where libelf.a pulls in ZSTD symbols from elf_compress.o), but
> >>> avoid breaking dynamic builds on systems without libzstd-dev.
> >>
> >> [...]
> >>
> >>
> >> So, while AI may be technically correct that the build will fail if
> >> libelf is installed and libzstd is not, it seems a far-fetched
> >> situation, given that libelf depends on libzstd.
> > 
> > This is not far-fetched, and we have build failure for v7.0-rc2 due to
> > this.
> > 
> >   ld: cannot find -lzstd: No such file or directory
> > 
> > Even though libelf is linked with libzstd, this does not imply
> > libzstd-devel (with headers and so library) is there when building.
> 
> Does AI's suggestion make sense in your case then?
> That is, make ZSTD_LIBS empty in case pkg-config didn't find libzstd?
> 
> I'm happy to fix this, the build shouldn't fail unless it must.
> 
> But I am curious how and why an environment building Linux with BTF
> (requiring build and run of resolve_btfids), which needs libelf-dev
> and presumably its dependencies, would exclude/avoid installing
> libzstd-dev?

Are you providing -lzstd just to link with libelf? I don't think you need to
care about zstd in that case. libelf is already linked with libzstd. If you
don't use libzstd functions yourself you don't need to link with -lzstd.

Example build without -lzstd:

  builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ grep zstd tools/bpf/resolve_btfids/Makefile
  ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null)

  builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ ldd ./tools/bpf/resolve_btfids/resolve_btfids
	  linux-vdso.so.1 (0x00007ff8b2329000)
	  libelf.so.1 => /lib64/libelf.so.1 (0x00007ff8b2287000)
	  libz.so.1 => /lib64/libz.so.1 (0x00007ff8b2269000)
	  libc.so.6 => /lib64/libc.so.6 (0x00007ff8b206e000)
	  libzstd.so.1 => /lib64/libzstd.so.1 (0x00007ff8b1fc8000)
	  /lib64/ld-linux-x86-64.so.2 (0x00007ff8b232b000)
  builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ rpm -q libzstd
  libzstd-1.5.5-alt2.x86_64
  builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ rpm -q libzstd-devel
  package libzstd-devel is not installed

lib*-devel/-dev packages only required if your source is directly using the
target lib, in other causes this is already handled.

Thanks,

> 
> Thanks.
> 
> > 
> > Thanks,
> > 
> >>
> >> I think we can leave the default -lzstd to have an explicit
> >> dependency in the Makefile.
> >>
> >>
> >>>
> >>> [ ... ]
> 

Re: [PATCH bpf v3 01/15] selftests/bpf: Pass through build flags to bpftool and resolve_btfids

[Ihor Solodrai]

On 3/2/26 12:27 PM, Vitaly Chikunov wrote:
> Ihor,
> 
> On Mon, Mar 02, 2026 at 10:01:59AM -0800, Ihor Solodrai wrote:
>> On 3/2/26 7:22 AM, Vitaly Chikunov wrote:
>>> On Fri, Feb 20, 2026 at 08:23:51PM -0800, Ihor Solodrai wrote:
>>>> On 2/20/26 2:57 PM, bot+bpf-ci@kernel.org wrote:
>>>>>> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
>>>>>> index 1733a6e93a07..ef083602b73a 100644
>>>>>> --- a/tools/bpf/resolve_btfids/Makefile
>>>>>> +++ b/tools/bpf/resolve_btfids/Makefile
>>>>>> @@ -65,6 +65,9 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
>>>>>>  LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
>>>>>>  LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
>>>>>>
>>>>>> +ZLIB_LIBS  := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz)
>>>>>> +ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null || echo -lzstd)
>>>>>
>>>>> The "|| echo -lzstd" fallback makes zstd an unconditional link
>>>>> dependency. On systems where libzstd-dev is not installed, pkg-config
>>>>> fails and the fallback provides -lzstd, but the linker cannot find the
>>>>> library and the build fails.
>>>>>
>>>>> bpftool handles the same transitive dependency conditionally via a
>>>>> feature test:
>>>>>
>>>>> tools/bpf/bpftool/Makefile:
>>>>>     ifeq ($(feature-libelf-zstd),1)
>>>>>     LIBS += -lzstd
>>>>>     LIBS_BOOTSTRAP += -lzstd
>>>>>     endif
>>>>>
>>>>> Would it be safer to drop the fallback here so ZSTD_LIBS is empty
>>>>> when zstd is not available?
>>>>>
>>>>>     ZSTD_LIBS := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null)
>>>>>
>>>>> This would still link zstd when present (needed for the static linking
>>>>> case where libelf.a pulls in ZSTD symbols from elf_compress.o), but
>>>>> avoid breaking dynamic builds on systems without libzstd-dev.
>>>>
>>>> [...]
>>>>
>>>>
>>>> So, while AI may be technically correct that the build will fail if
>>>> libelf is installed and libzstd is not, it seems a far-fetched
>>>> situation, given that libelf depends on libzstd.
>>>
>>> This is not far-fetched, and we have build failure for v7.0-rc2 due to
>>> this.
>>>
>>>   ld: cannot find -lzstd: No such file or directory
>>>
>>> Even though libelf is linked with libzstd, this does not imply
>>> libzstd-devel (with headers and so library) is there when building.
>>
>> Does AI's suggestion make sense in your case then?
>> That is, make ZSTD_LIBS empty in case pkg-config didn't find libzstd?
>>
>> I'm happy to fix this, the build shouldn't fail unless it must.
>>
>> But I am curious how and why an environment building Linux with BTF
>> (requiring build and run of resolve_btfids), which needs libelf-dev
>> and presumably its dependencies, would exclude/avoid installing
>> libzstd-dev?
> 
> Are you providing -lzstd just to link with libelf? I don't think you need to

An explicit -lzstd flag was added to enable a static build [1].

> care about zstd in that case. libelf is already linked with libzstd. If you
> don't use libzstd functions yourself you don't need to link with -lzstd.
> 
> Example build without -lzstd:
> 
>   builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ grep zstd tools/bpf/resolve_btfids/Makefile
>   ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null)
> 
>   builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ ldd ./tools/bpf/resolve_btfids/resolve_btfids
> 	  linux-vdso.so.1 (0x00007ff8b2329000)
> 	  libelf.so.1 => /lib64/libelf.so.1 (0x00007ff8b2287000)
> 	  libz.so.1 => /lib64/libz.so.1 (0x00007ff8b2269000)
> 	  libc.so.6 => /lib64/libc.so.6 (0x00007ff8b206e000)
> 	  libzstd.so.1 => /lib64/libzstd.so.1 (0x00007ff8b1fc8000)
> 	  /lib64/ld-linux-x86-64.so.2 (0x00007ff8b232b000)
>   builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ rpm -q libzstd
>   libzstd-1.5.5-alt2.x86_64
>   builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ rpm -q libzstd-devel
>   package libzstd-devel is not installed
> 
> lib*-devel/-dev packages only required if your source is directly using the
> target lib, in other causes this is already handled.

The issue that AI has raised is whether to leave -lzstd link flag by
default or not. I decided to leave it on the assumption that the
environments building Linux with BTF (hence building and running
resovle_btfids) would have libelf-dev installed (because -lelf has
been a requirement forever [2]), and libzstd-dev is its dependency.

I checked a few recent distros, all of them have libzstd-dev as a
direct dependency of libelf-dev, which supports my assumption:

  # Fedora
  $ dnf repoquery --providers-of=depends elfutils-libelf-devel
  Updating and loading repositories:
  Repositories loaded.
  elfutils-libelf-0:0.194-1.fc43.i686
  elfutils-libelf-0:0.194-1.fc43.x86_64
  libzstd-devel-0:1.5.7-2.fc43.i686
  libzstd-devel-0:1.5.7-2.fc43.x86_64
  pkgconf-pkg-config-0:2.3.0-3.fc43.i686
  pkgconf-pkg-config-0:2.3.0-3.fc43.x86_64
  zlib-ng-compat-devel-0:2.3.3-1.fc43.i686
  zlib-ng-compat-devel-0:2.3.3-1.fc43.x86_64

  # Ubuntu
  $ apt info libelf-dev
  Package: libelf-dev
  Version: 0.190-1.1ubuntu0.1
  Priority: optional
  Section: libdevel
  Source: elfutils
  Origin: Ubuntu
  Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
  Original-Maintainer: Debian Elfutils Maintainers <debian-gcc@lists.debian.org>
  Bugs: https://bugs.launchpad.net/ubuntu/+filebug
  Installed-Size: 385 kB
  Depends: libelf1t64 (= 0.190-1.1ubuntu0.1), zlib1g-dev, libzstd-dev
  Conflicts: libelfg0-dev
  [...]

  # Debian
  $ apt info libelf-dev
  Package: libelf-dev
  Version: 0.192-4
  Priority: optional
  Section: libdevel
  Source: elfutils
  Maintainer: Debian Elfutils Maintainers <debian-gcc@lists.debian.org>
  Installed-Size: 420 kB
  Depends: libelf1t64 (= 0.192-4), zlib1g-dev, libzstd-dev
  Conflicts: libelfg0-dev
  [...]


Of course it's plausible to have a system where libelf-dev is present
while libzstd-dev is not, as demonstrated by you running one.

Anyways this is easy to fix, I'll send a patch shortly.

[1] https://lore.kernel.org/bpf/4ff82800-2daa-4b9f-95a9-6f512859ee70@linux.dev/
[2] https://lore.kernel.org/bpf/20200711215329.41165-2-jolsa@kernel.org/


> 
> Thanks,
> 
>>
>> Thanks.
>>
>>>
>>> Thanks,
>>>
>>>>
>>>> I think we can leave the default -lzstd to have an explicit
>>>> dependency in the Makefile.
>>>>
>>>>
>>>>>
>>>>> [ ... ]
>>

Re: [PATCH bpf v3 01/15] selftests/bpf: Pass through build flags to bpftool and resolve_btfids

[Vitaly Chikunov]

Ihor,

On Mon, Mar 02, 2026 at 02:42:11PM -0800, Ihor Solodrai wrote:
> On 3/2/26 12:27 PM, Vitaly Chikunov wrote:
> > On Mon, Mar 02, 2026 at 10:01:59AM -0800, Ihor Solodrai wrote:
> >> On 3/2/26 7:22 AM, Vitaly Chikunov wrote:
> >>> On Fri, Feb 20, 2026 at 08:23:51PM -0800, Ihor Solodrai wrote:
> >>>> On 2/20/26 2:57 PM, bot+bpf-ci@kernel.org wrote:
> >>>>>> diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
> >>>>>> index 1733a6e93a07..ef083602b73a 100644
> >>>>>> --- a/tools/bpf/resolve_btfids/Makefile
> >>>>>> +++ b/tools/bpf/resolve_btfids/Makefile
> >>>>>> @@ -65,6 +65,9 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
> >>>>>>  LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
> >>>>>>  LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
> >>>>>>
> >>>>>> +ZLIB_LIBS  := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz)
> >>>>>> +ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null || echo -lzstd)
> >>>>>
> >>>>> The "|| echo -lzstd" fallback makes zstd an unconditional link
> >>>>> dependency. On systems where libzstd-dev is not installed, pkg-config
> >>>>> fails and the fallback provides -lzstd, but the linker cannot find the
> >>>>> library and the build fails.
> >>>>>
> >>>>> bpftool handles the same transitive dependency conditionally via a
> >>>>> feature test:
> >>>>>
> >>>>> tools/bpf/bpftool/Makefile:
> >>>>>     ifeq ($(feature-libelf-zstd),1)
> >>>>>     LIBS += -lzstd
> >>>>>     LIBS_BOOTSTRAP += -lzstd
> >>>>>     endif
> >>>>>
> >>>>> Would it be safer to drop the fallback here so ZSTD_LIBS is empty
> >>>>> when zstd is not available?
> >>>>>
> >>>>>     ZSTD_LIBS := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null)
> >>>>>
> >>>>> This would still link zstd when present (needed for the static linking
> >>>>> case where libelf.a pulls in ZSTD symbols from elf_compress.o), but
> >>>>> avoid breaking dynamic builds on systems without libzstd-dev.
> >>>>
> >>>> [...]
> >>>>
> >>>>
> >>>> So, while AI may be technically correct that the build will fail if
> >>>> libelf is installed and libzstd is not, it seems a far-fetched
> >>>> situation, given that libelf depends on libzstd.
> >>>
> >>> This is not far-fetched, and we have build failure for v7.0-rc2 due to
> >>> this.
> >>>
> >>>   ld: cannot find -lzstd: No such file or directory
> >>>
> >>> Even though libelf is linked with libzstd, this does not imply
> >>> libzstd-devel (with headers and so library) is there when building.
> >>
> >> Does AI's suggestion make sense in your case then?
> >> That is, make ZSTD_LIBS empty in case pkg-config didn't find libzstd?
> >>
> >> I'm happy to fix this, the build shouldn't fail unless it must.
> >>
> >> But I am curious how and why an environment building Linux with BTF
> >> (requiring build and run of resolve_btfids), which needs libelf-dev
> >> and presumably its dependencies, would exclude/avoid installing
> >> libzstd-dev?
> > 
> > Are you providing -lzstd just to link with libelf? I don't think you need to
> 
> An explicit -lzstd flag was added to enable a static build [1].
> 
> > care about zstd in that case. libelf is already linked with libzstd. If you
> > don't use libzstd functions yourself you don't need to link with -lzstd.
> > 
> > Example build without -lzstd:
> > 
> >   builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ grep zstd tools/bpf/resolve_btfids/Makefile
> >   ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null)
> > 
> >   builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ ldd ./tools/bpf/resolve_btfids/resolve_btfids
> > 	  linux-vdso.so.1 (0x00007ff8b2329000)
> > 	  libelf.so.1 => /lib64/libelf.so.1 (0x00007ff8b2287000)
> > 	  libz.so.1 => /lib64/libz.so.1 (0x00007ff8b2269000)
> > 	  libc.so.6 => /lib64/libc.so.6 (0x00007ff8b206e000)
> > 	  libzstd.so.1 => /lib64/libzstd.so.1 (0x00007ff8b1fc8000)
> > 	  /lib64/ld-linux-x86-64.so.2 (0x00007ff8b232b000)
> >   builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ rpm -q libzstd
> >   libzstd-1.5.5-alt2.x86_64
> >   builder@x86_64:~/RPM/BUILD/kernel-image-7.0-rc2$ rpm -q libzstd-devel
> >   package libzstd-devel is not installed
> > 
> > lib*-devel/-dev packages only required if your source is directly using the
> > target lib, in other causes this is already handled.
> 
> The issue that AI has raised is whether to leave -lzstd link flag by
> default or not. I decided to leave it on the assumption that the
> environments building Linux with BTF (hence building and running
> resovle_btfids) would have libelf-dev installed (because -lelf has
> been a requirement forever [2]), and libzstd-dev is its dependency.
> 
> I checked a few recent distros, all of them have libzstd-dev as a
> direct dependency of libelf-dev, which supports my assumption:
> 
>   # Fedora
>   $ dnf repoquery --providers-of=depends elfutils-libelf-devel
>   Updating and loading repositories:
>   Repositories loaded.
>   elfutils-libelf-0:0.194-1.fc43.i686
>   elfutils-libelf-0:0.194-1.fc43.x86_64
>   libzstd-devel-0:1.5.7-2.fc43.i686
>   libzstd-devel-0:1.5.7-2.fc43.x86_64

Interesting, but looks like this is not needed package dependency.

  [fodora:rawhide@docker /]# grep zstd /usr/lib64/pkgconfig/libelf.pc
  Requires.private: zlib libzstd

It's only a private dependency not exposed to the application.
pkg-config will not add -lzstd to link with libelf.so. (Unless it's
-static linking.) See pkg-config(1):

  Requires.private:
    A list of packages required by this package. The difference from Requires is
    that the packages listed under Requires.private are not taken into account when
    a flag list is computed for dynamically linked executable (i.e., when --static
    was not specified).  In the situation where each .pc file corresponds to a
    library, Requires.private shall be used exclusively to specify the dependencies
    between the libraries.

Perhaps, for your static linking case, you just need to extract -static from
EXTRA_LDFLAGS and add it to `pkg-config libelf --libs` to get the list of
static libraries to link with libelf, without defining ZSTD_LIBS at all.
This may provide other important flags besides these, see for example:

  alt:sisyphus# pkg-config libelf --libs --static
  -lelf -lz -lzstd -pthread

I think it's better to rely on pkg-config instead of guessing all the required
linking flags.


>   pkgconf-pkg-config-0:2.3.0-3.fc43.i686
>   pkgconf-pkg-config-0:2.3.0-3.fc43.x86_64
>   zlib-ng-compat-devel-0:2.3.3-1.fc43.i686
>   zlib-ng-compat-devel-0:2.3.3-1.fc43.x86_64
> 
>   # Ubuntu
>   $ apt info libelf-dev
>   Package: libelf-dev
>   Version: 0.190-1.1ubuntu0.1
>   Priority: optional
>   Section: libdevel
>   Source: elfutils
>   Origin: Ubuntu
>   Maintainer: Ubuntu Developers <ubuntu-devel-discuss@lists.ubuntu.com>
>   Original-Maintainer: Debian Elfutils Maintainers <debian-gcc@lists.debian.org>
>   Bugs: https://bugs.launchpad.net/ubuntu/+filebug
>   Installed-Size: 385 kB
>   Depends: libelf1t64 (= 0.190-1.1ubuntu0.1), zlib1g-dev, libzstd-dev
>   Conflicts: libelfg0-dev
>   [...]
> 
>   # Debian
>   $ apt info libelf-dev
>   Package: libelf-dev
>   Version: 0.192-4
>   Priority: optional
>   Section: libdevel
>   Source: elfutils
>   Maintainer: Debian Elfutils Maintainers <debian-gcc@lists.debian.org>
>   Installed-Size: 420 kB
>   Depends: libelf1t64 (= 0.192-4), zlib1g-dev, libzstd-dev
>   Conflicts: libelfg0-dev
>   [...]

I don't know why these distros do this sort of dependency. In ALT Linux we
don't require libzstd-devel for linelf-devel, also, I just checked OpenMandriva
and it does not require this too. But, openSUSE requires libzstd-devel.

> Of course it's plausible to have a system where libelf-dev is present
> while libzstd-dev is not, as demonstrated by you running one.
> 
> Anyways this is easy to fix, I'll send a patch shortly.

Thanks,

> 
> [1] https://lore.kernel.org/bpf/4ff82800-2daa-4b9f-95a9-6f512859ee70@linux.dev/
> [2] https://lore.kernel.org/bpf/20200711215329.41165-2-jolsa@kernel.org/
> 
> 
> > 
> > Thanks,
> > 
> >>
> >> Thanks.
> >>
> >>>
> >>> Thanks,
> >>>
> >>>>
> >>>> I think we can leave the default -lzstd to have an explicit
> >>>> dependency in the Makefile.
> >>>>
> >>>>
> >>>>>
> >>>>> [ ... ]
> >>