Re: [PATCH] recordmcount: Correct st_shndx handling

From: Ard Biesheuvel
Date: Tue Jun 08 2021 - 06:37:19 EST


On Tue, 8 Jun 2021 at 12:34, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
>
> One should only use st_shndx when >SHN_UNDEF and <SHN_LORESERVE. When
> SHN_XINDEX, then use .symtab_shndx. Otherwise use 0.
>
> This handles the case: st_shndx >= SHN_LORESERVE && st_shndx != SHN_XINDEX.
>
> Reported-by: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> Tested-by: Mark-PK Tsai <mark-pk.tsai@xxxxxxxxxxxx>

Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>

> ---
> scripts/recordmcount.h | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> --- a/scripts/recordmcount.h
> +++ b/scripts/recordmcount.h
> @@ -194,13 +194,18 @@ static unsigned int get_symindex(Elf_Sym
> unsigned long offset;
> int index;
>
> - if (sym->st_shndx != SHN_XINDEX)
> + if (sym->st_shndx > SHN_UNDEF &&
> + sym->st_shndx < SHN_LORESERVE)
> return w2(sym->st_shndx);
>
> - offset = (unsigned long)sym - (unsigned long)symtab;
> - index = offset / sizeof(*sym);
> + if (sym->st_shndx == SHN_XINDEX) {
> + offset = (unsigned long)sym - (unsigned long)symtab;
> + index = offset / sizeof(*sym);
>
> - return w(symtab_shndx[index]);
> + return w(symtab_shndx[index]);
> + }
> +
> + return 0;
> }
>
> static unsigned int get_shnum(Elf_Ehdr const *ehdr, Elf_Shdr const *shdr0)