util/grub-module-verifierXX: Add e_shoff check in get_shdr()

In util/grub-module-verifierXX.c, the function get_shdr() is used to obtain the
section header at a given index but isn't checking that there is an offset for
the section header table. To validate that there is, we can check that e_shoff
isn't 0.

Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
This commit is contained in:
Alec Brown 2022-05-26 15:29:51 -04:00 committed by Daniel Kiper
parent 253da39c15
commit 27e53de2fd

View File

@ -134,6 +134,9 @@ grub_target_to_host_real (const struct grub_module_verifier_arch *arch, grub_uin
static Elf_Shdr *
get_shdr (const struct grub_module_verifier_arch *arch, Elf_Ehdr *e, Elf_Word index)
{
if (grub_target_to_host (e->e_shoff) == 0)
grub_util_error ("Invalid section header offset");
return (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff) +
index * grub_target_to_host16 (e->e_shentsize));
}