Re: [PATCH] libbpf: Ignore exception frame section

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Incomplete handling of exception frame sections by using exact string matching instead of prefix matching.
--

--- Patch [1]: [PATCH] libbpf: Ignore exception frame section ---
commit 7e5607d9374ac0c905a5c8970316c258ed4eb5cf
Author: Tw <[email protected]>

libbpf: Ignore exception frame section
    
This commit updates the ELF section filtering logic to ignore ".eh_frame"
sections during BPF object linking and loading. This resolves issues when
building BPF programs with compilers that emit exception handling frames,
as they are not needed by the kernel.

> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index b749c01742ee0..05727c418c402 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -3867,7 +3867,8 @@ static Elf64_Rel *elf_rel_by_idx(Elf_Data *data, size_t idx)
>  static bool is_sec_name_dwarf(const char *name)
>  {
>  	/* approximation, but the actual list is too long */
> -	return str_has_pfx(name, ".debug_");
> +	return str_has_pfx(name, ".debug_") ||
> +		   strcmp(name, ".eh_frame") == 0;

[Severity: Medium]
Does this exact string match correctly handle variants like ".eh_frame_hdr" 
or function-split ".eh_frame.*" sections?

If a compiler emits these variant sections, they would bypass this filter and
could potentially cause build-time link failures against STT_SECTION. Would
it be more robust to use a prefix match like str_has_pfx() here, similar to 
how ".debug_" is handled?

>  }
>  
>  static bool ignore_elf_section(Elf64_Shdr *hdr, const char *name)

[ ... ]

> diff --git a/tools/lib/bpf/linker.c b/tools/lib/bpf/linker.c
> index 78f92c39290af..1fb0efdbfae7f 100644
> --- a/tools/lib/bpf/linker.c
> +++ b/tools/lib/bpf/linker.c
> @@ -599,7 +599,8 @@ int bpf_linker__add_buf(struct bpf_linker *linker, void *buf, size_t buf_sz,
>  static bool is_dwarf_sec_name(const char *name)
>  {
>  	/* approximation, but the actual list is too long */
> -	return strncmp(name, ".debug_", sizeof(".debug_") - 1) == 0;
> +	return strncmp(name, ".debug_", sizeof(".debug_") - 1) == 0 ||
> +		   strcmp(name, ".eh_frame") == 0;

[Severity: Medium]
Similarly, would it be beneficial to use a prefix match (e.g. strncmp) here
to ensure we also ignore related exception frame sections?

>  }
>  
>  static bool is_ignored_sec(struct src_sec *sec)

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=1