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objtool: Preserve special st_shndx indexes in elf_update_symbol 

elf_update_symbol fails to preserve the special st_shndx values
between [SHN_LORESERVE, SHN_HIRESERVE], which results in it
converting SHN_ABS entries into SHN_UNDEF, for example. Explicitly
check for the special indexes and ensure these symbols are not
marked undefined.

Fixes: ead165fa10 ("objtool: Fix symbol creation")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220908215504.3686827-17-samitolvanen@google.com
This commit is contained in:
Sami Tolvanen 2022-09-08 14:54:58 -07:00 committed by Kees Cook
parent 5659b598b4
commit 5141d3a06b
1 changed files with 6 additions and 1 deletions
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7
tools/objtool/elf.c
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@ -619,6 +619,11 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab,
Elf64_Xword entsize = symtab->sh.sh_entsize;
int max_idx, idx = sym->idx;
Elf_Scn *s, *t = NULL;
bool is_special_shndx = sym->sym.st_shndx >= SHN_LORESERVE &&
sym->sym.st_shndx != SHN_XINDEX;
if (is_special_shndx)
shndx = sym->sym.st_shndx;
s = elf_getscn(elf->elf, symtab->idx);
if (!s) {
@ -704,7 +709,7 @@ static int elf_update_symbol(struct elf *elf, struct section *symtab,
}
/* setup extended section index magic and write the symbol */
if (shndx >= SHN_UNDEF && shndx < SHN_LORESERVE) {
if ((shndx >= SHN_UNDEF && shndx < SHN_LORESERVE) || is_special_shndx) {
sym->sym.st_shndx = shndx;
if (!shndx_data)
shndx = 0;