Commit 5141d3a0 authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Kees Cook
Browse files

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: ead165fa ("objtool: Fix symbol creation")
Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
Acked-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220908215504.3686827-17-samitolvanen@google.com
parent 5659b598

tools/objtool/elf.c

+6 −1
Original line number Diff line number Diff line
@@ -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;