From: Jiri Olsa <olsajiri@gmail.com>
To: Ihor Solodrai <ihor.solodrai@linux.dev>
Cc: "Alexei Starovoitov" <ast@kernel.org>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Eduard Zingerman" <eddyz87@gmail.com>,
"Amery Hung" <ameryhung@gmail.com>,
"Mykyta Yatsenko" <yatsenko@meta.com>,
"Alexis Lothoré" <alexis.lothore@bootlin.com>,
bpf@vger.kernel.org, linux-kernel@vger.kernel.org,
kernel-team@meta.com
Subject: Re: [PATCH bpf-next v1 04/14] selftests/bpf: Refactor bpf_get_ksyms() trace helper
Date: Thu, 12 Feb 2026 12:29:04 +0100 [thread overview]
Message-ID: <aY25gB6NDmlPJPUB@krava> (raw)
In-Reply-To: <20260212011356.3266753-5-ihor.solodrai@linux.dev>
On Wed, Feb 11, 2026 at 05:13:46PM -0800, Ihor Solodrai wrote:
> ASAN reported a memory leak in bpf_get_ksyms(): it allocates a struct
> ksyms internally and never frees it.
>
> Moe 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 | 9 ++++----
> .../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, 30 insertions(+), 25 deletions(-)
>
> diff --git a/tools/testing/selftests/bpf/benchs/bench_trigger.c b/tools/testing/selftests/bpf/benchs/bench_trigger.c
> index aeec9edd3851..7231b88cf21a 100644
> --- a/tools/testing/selftests/bpf/benchs/bench_trigger.c
> +++ b/tools/testing/selftests/bpf/benchs/bench_trigger.c
> @@ -230,8 +230,7 @@ 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 ksyms *ksyms = NULL;
>
> /* Some recursive functions will be skipped in
> * bpf_get_ksyms -> skip_entry, as they can introduce sufficient
> @@ -241,13 +240,13 @@ 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)) {
hi,
missing free_kallsyms_local call in here ?
> 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);
> + }
I think we could just call free_kallsyms_local unconditionally in here
and fix callers to free syms pointer? seems easier than adding filtered*
fields to ksyms
thanks,
jirak
> 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
>
>
next prev parent reply other threads:[~2026-02-12 11:29 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-12 1:13 [PATCH bpf-next v1 00/14] selftests/bpf: Fixes for userspace ASAN Ihor Solodrai
2026-02-12 1:13 ` [PATCH bpf-next v1 01/14] selftests/bpf: Pass through build flags to bpftool and resolve_btfids Ihor Solodrai
2026-02-12 2:39 ` Alexei Starovoitov
2026-02-12 3:08 ` Ihor Solodrai
2026-02-13 0:08 ` Ihor Solodrai
2026-02-12 1:13 ` [PATCH bpf-next v1 02/14] resolve_btfids: Fix memory leaks reported by ASAN Ihor Solodrai
2026-02-12 11:28 ` Jiri Olsa
2026-02-12 1:13 ` [PATCH bpf-next v1 03/14] selftests/bpf: Add DENYLIST.asan Ihor Solodrai
2026-02-12 1:13 ` [PATCH bpf-next v1 04/14] selftests/bpf: Refactor bpf_get_ksyms() trace helper Ihor Solodrai
2026-02-12 11:29 ` Jiri Olsa [this message]
2026-02-17 20:42 ` Ihor Solodrai
2026-02-18 13:14 ` Jiri Olsa
2026-02-13 9:56 ` Alexis Lothoré
2026-02-12 1:13 ` [PATCH bpf-next v1 05/14] selftests/bpf: Fix memory leaks in tests Ihor Solodrai
2026-02-12 23:08 ` Eduard Zingerman
2026-02-12 1:13 ` [PATCH bpf-next v1 06/14] selftests/bpf: Fix cleanup in check_fd_array_cnt__fd_array_too_big() Ihor Solodrai
2026-02-12 23:17 ` Eduard Zingerman
2026-02-12 1:13 ` [PATCH bpf-next v1 07/14] veristat: Fix a memory leak for preset ENUMERATOR Ihor Solodrai
2026-02-12 13:37 ` Mykyta Yatsenko
2026-02-12 1:13 ` [PATCH bpf-next v1 08/14] selftests/bpf: Fix use-after-free in xdp_metadata test Ihor Solodrai
2026-02-12 13:40 ` Mykyta Yatsenko
2026-02-12 1:13 ` [PATCH bpf-next v1 09/14] selftests/bpf: Fix double thread join in uprobe_multi_test Ihor Solodrai
2026-02-12 11:29 ` Jiri Olsa
2026-02-12 14:49 ` Mykyta Yatsenko
2026-02-13 16:48 ` Jiri Olsa
2026-02-12 1:13 ` [PATCH bpf-next v1 10/14] selftests/bpf: Fix resource leaks caused by missing cleanups Ihor Solodrai
2026-02-13 0:45 ` Eduard Zingerman
2026-02-12 1:13 ` [PATCH bpf-next v1 11/14] selftests/bpf: Free bpf_object in test_sysctl Ihor Solodrai
2026-02-13 0:54 ` Eduard Zingerman
2026-02-12 1:13 ` [PATCH bpf-next v1 12/14] selftests/bpf: Fix array bounds warning in jit_disasm_helpers Ihor Solodrai
2026-02-13 1:02 ` Eduard Zingerman
2026-02-12 1:13 ` [PATCH bpf-next v1 13/14] selftests/bpf: Fix out-of-bounds array access bugs reported by ASAN Ihor Solodrai
2026-02-13 1:11 ` Eduard Zingerman
2026-02-17 23:27 ` Ihor Solodrai
2026-02-12 1:13 ` [PATCH bpf-next v1 14/14] selftests/bpf: Check BPFTOOL env var in detect_bpftool_path() Ihor Solodrai
2026-02-12 15:03 ` Mykyta Yatsenko
2026-02-13 10:36 ` Alexis Lothoré
2026-02-12 22:00 ` [PATCH bpf-next v1 00/14] selftests/bpf: Fixes for userspace ASAN Eduard Zingerman
2026-02-12 23:57 ` Ihor Solodrai
2026-02-13 0:23 ` Eduard Zingerman
2026-02-13 16:13 ` Ihor Solodrai
2026-02-13 18:06 ` Eduard Zingerman
2026-02-12 23:26 ` Eduard Zingerman
2026-02-13 17:56 ` Ihor Solodrai
2026-02-13 18:09 ` Eduard Zingerman
2026-02-13 18:29 ` Ihor Solodrai
2026-02-13 18:35 ` Eduard Zingerman
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