[PATCH bpf-next 1/2] libbpf: use strlcpy() in path resolution fallback logic

[PATCH bpf-next 1/2] libbpf: use strlcpy() in path resolution fallback logic

[Andrii Nakryiko]

Coverity static analyzer complains that strcpy() can cause buffer
overflow. Use libbpf_strlcpy() instead to be 100% sure this doesn't
happen.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/usdt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/usdt.c b/tools/lib/bpf/usdt.c
index b699e720136a..5d7ba171ad39 100644
--- a/tools/lib/bpf/usdt.c
+++ b/tools/lib/bpf/usdt.c
@@ -456,7 +456,7 @@ static int parse_lib_segs(int pid, const char *lib_path, struct elf_seg **segs,
 	if (!realpath(lib_path, path)) {
 		pr_warn("usdt: failed to get absolute path of '%s' (err %d), using path as is...\n",
 			lib_path, -errno);
-		strcpy(path, lib_path);
+		libbpf_strlcpy(path, lib_path, sizeof(path));
 	}
 
 proceed:
-- 
2.30.2

[PATCH bpf-next 2/2] libbpf: allow WEAK and GLOBAL bindings during BTF fixup

[Andrii Nakryiko]

During BTF fix up for global variables, global variable can be global
weak and will have STB_WEAK binding in ELF. Support such global
variables in addition to non-weak ones.

This is not the problem when using BPF static linking, as BPF static
linker "fixes up" BTF during generation so that libbpf doesn't have to
do it anymore during bpf_object__open(), which led to this not being
noticed for a while, along with a pretty rare (currently) use of __weak
variables and maps.

Reported-by: Hengqi Chen <hengqi.chen@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 tools/lib/bpf/libbpf.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 016ecdd1c3e1..9deb1fc67f19 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -1401,8 +1401,11 @@ static int find_elf_var_offset(const struct bpf_object *obj, const char *name, _
 	for (si = 0; si < symbols->d_size / sizeof(Elf64_Sym); si++) {
 		Elf64_Sym *sym = elf_sym_by_idx(obj, si);
 
-		if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL ||
-		    ELF64_ST_TYPE(sym->st_info) != STT_OBJECT)
+		if (ELF64_ST_TYPE(sym->st_info) != STT_OBJECT)
+			continue;
+
+		if (ELF64_ST_BIND(sym->st_info) != STB_GLOBAL &&
+		    ELF64_ST_BIND(sym->st_info) != STB_WEAK)
 			continue;
 
 		sname = elf_sym_str(obj, sym->st_name);
-- 
2.30.2

Re: [PATCH bpf-next 1/2] libbpf: use strlcpy() in path resolution fallback logic

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Thu, 7 Apr 2022 16:04:45 -0700 you wrote:
> Coverity static analyzer complains that strcpy() can cause buffer
> overflow. Use libbpf_strlcpy() instead to be 100% sure this doesn't
> happen.
> 
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
> ---
>  tools/lib/bpf/usdt.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Here is the summary with links:
  - [bpf-next,1/2] libbpf: use strlcpy() in path resolution fallback logic
    https://git.kernel.org/bpf/bpf-next/c/3c0dfe6e4c43
  - [bpf-next,2/2] libbpf: allow WEAK and GLOBAL bindings during BTF fixup
    https://git.kernel.org/bpf/bpf-next/c/3a06ec0a996d

You are awesome, thank you!
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