[PATCH bpf-next 0/3] libbpf: fix several issues reported by static analysers

[PATCH bpf-next 0/3] libbpf: fix several issues reported by static analysers

[Viktor Malik]

Fixing several issues reported by Coverity and Clang Static Analyzer
(scan-build) for libbpf, mostly removing unnecessary symbols and
assignments.

No functional changes should be introduced.

Viktor Malik (3):
  libbpf: remove unnecessary ternary operator
  libbpf: remove several dead assignments
  libbpf: cleanup linker_append_elf_relos

 tools/lib/bpf/btf.c       |  2 --
 tools/lib/bpf/libbpf.c    |  3 +--
 tools/lib/bpf/linker.c    | 11 ++---------
 tools/lib/bpf/relo_core.c |  3 ---
 4 files changed, 3 insertions(+), 16 deletions(-)

-- 
2.39.1

[PATCH bpf-next 1/3] libbpf: remove unnecessary ternary operator

[Viktor Malik]

Coverity reports that the first check of 'err' in bpf_object__init_maps
is always false as 'err' is initialized to 0 at that point. Remove the
unnecessary ternary operator.

Signed-off-by: Viktor Malik <vmalik@redhat.com>
---
 tools/lib/bpf/libbpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 05c4db355f28..905193d98885 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -2615,7 +2615,7 @@ static int bpf_object__init_maps(struct bpf_object *obj,
 	strict = !OPTS_GET(opts, relaxed_maps, false);
 	pin_root_path = OPTS_GET(opts, pin_root_path, NULL);
 
-	err = err ?: bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
+	err = bpf_object__init_user_btf_maps(obj, strict, pin_root_path);
 	err = err ?: bpf_object__init_global_data_maps(obj);
 	err = err ?: bpf_object__init_kconfig_map(obj);
 	err = err ?: bpf_object__init_struct_ops_maps(obj);
-- 
2.39.1

[PATCH bpf-next 2/3] libbpf: remove several dead assignments

[Viktor Malik]

Clang Static Analyzer (scan-build) reports several dead assignments in
libbpf where the assigned value is unconditionally overridden by another
value before it is read. Remove these assignments.

Signed-off-by: Viktor Malik <vmalik@redhat.com>
---
 tools/lib/bpf/btf.c       | 2 --
 tools/lib/bpf/libbpf.c    | 1 -
 tools/lib/bpf/relo_core.c | 3 ---
 3 files changed, 6 deletions(-)

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 9181d36118d2..0a2c079244b6 100644
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -1000,8 +1000,6 @@ static struct btf *btf_parse_elf(const char *path, struct btf *base_btf,
 		}
 	}
 
-	err = 0;
-
 	if (!btf_data) {
 		pr_warn("failed to find '%s' ELF section in %s\n", BTF_ELF_SEC, path);
 		err = -ENODATA;
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 905193d98885..ba9e7e2b7951 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -798,7 +798,6 @@ bpf_object__add_programs(struct bpf_object *obj, Elf_Data *sec_data,
 	progs = obj->programs;
 	nr_progs = obj->nr_programs;
 	nr_syms = symbols->d_size / sizeof(Elf64_Sym);
-	sec_off = 0;
 
 	for (i = 0; i < nr_syms; i++) {
 		sym = elf_sym_by_idx(obj, i);
diff --git a/tools/lib/bpf/relo_core.c b/tools/lib/bpf/relo_core.c
index c4b0e81ae293..a26b2f5fa0fc 100644
--- a/tools/lib/bpf/relo_core.c
+++ b/tools/lib/bpf/relo_core.c
@@ -1551,9 +1551,6 @@ int __bpf_core_types_match(const struct btf *local_btf, __u32 local_id, const st
 	if (level <= 0)
 		return -EINVAL;
 
-	local_t = btf_type_by_id(local_btf, local_id);
-	targ_t = btf_type_by_id(targ_btf, targ_id);
-
 recur:
 	depth--;
 	if (depth < 0)
-- 
2.39.1

[PATCH bpf-next 3/3] libbpf: cleanup linker_append_elf_relos

[Viktor Malik]

Clang Static Analyser (scan-build) reports some unused symbols and dead
assignments in the linker_append_elf_relos function. Clean these up.

Signed-off-by: Viktor Malik <vmalik@redhat.com>
---
 tools/lib/bpf/linker.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
index 4ac02c28e152..d7069780984a 100644
--- a/tools/lib/bpf/linker.c
+++ b/tools/lib/bpf/linker.c
@@ -1997,7 +1997,6 @@ static int linker_append_elf_sym(struct bpf_linker *linker, struct src_obj *obj,
 static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *obj)
 {
 	struct src_sec *src_symtab = &obj->secs[obj->symtab_sec_idx];
-	struct dst_sec *dst_symtab;
 	int i, err;
 
 	for (i = 1; i < obj->sec_cnt; i++) {
@@ -2030,9 +2029,6 @@ static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *ob
 			return -1;
 		}
 
-		/* add_dst_sec() above could have invalidated linker->secs */
-		dst_symtab = &linker->secs[linker->symtab_sec_idx];
-
 		/* shdr->sh_link points to SYMTAB */
 		dst_sec->shdr->sh_link = linker->symtab_sec_idx;
 
@@ -2049,16 +2045,13 @@ static int linker_append_elf_relos(struct bpf_linker *linker, struct src_obj *ob
 		dst_rel = dst_sec->raw_data + src_sec->dst_off;
 		n = src_sec->shdr->sh_size / src_sec->shdr->sh_entsize;
 		for (j = 0; j < n; j++, src_rel++, dst_rel++) {
-			size_t src_sym_idx = ELF64_R_SYM(src_rel->r_info);
-			size_t sym_type = ELF64_R_TYPE(src_rel->r_info);
-			Elf64_Sym *src_sym, *dst_sym;
-			size_t dst_sym_idx;
+			size_t src_sym_idx, dst_sym_idx, sym_type;
+			Elf64_Sym *src_sym;
 
 			src_sym_idx = ELF64_R_SYM(src_rel->r_info);
 			src_sym = src_symtab->data->d_buf + sizeof(*src_sym) * src_sym_idx;
 
 			dst_sym_idx = obj->sym_map[src_sym_idx];
-			dst_sym = dst_symtab->raw_data + sizeof(*dst_sym) * dst_sym_idx;
 			dst_rel->r_offset += src_linked_sec->dst_off;
 			sym_type = ELF64_R_TYPE(src_rel->r_info);
 			dst_rel->r_info = ELF64_R_INFO(dst_sym_idx, sym_type);
-- 
2.39.1

Re: [PATCH bpf-next 0/3] libbpf: fix several issues reported by static analysers

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Andrii Nakryiko <andrii@kernel.org>:

On Wed,  1 Mar 2023 09:53:52 +0100 you wrote:
> Fixing several issues reported by Coverity and Clang Static Analyzer
> (scan-build) for libbpf, mostly removing unnecessary symbols and
> assignments.
> 
> No functional changes should be introduced.
> 
> Viktor Malik (3):
>   libbpf: remove unnecessary ternary operator
>   libbpf: remove several dead assignments
>   libbpf: cleanup linker_append_elf_relos
> 
> [...]

Here is the summary with links:
  - [bpf-next,1/3] libbpf: remove unnecessary ternary operator
    https://git.kernel.org/bpf/bpf-next/c/40e1bcab1e4c
  - [bpf-next,2/3] libbpf: remove several dead assignments
    https://git.kernel.org/bpf/bpf-next/c/7832d06bd9f9
  - [bpf-next,3/3] libbpf: cleanup linker_append_elf_relos
    https://git.kernel.org/bpf/bpf-next/c/4672129127ee

You are awesome, thank you!
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