This is a note to let you know that I've just added the patch titled
module: fix [e_shstrndx].sh_size=0 OOB access
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
module-fix-e_shstrndx-.sh_size-0-oob-access.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 1fc8cfecf39c2e0b0a67d72401f23424ee1f20ec
Author: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Date: Wed May 4 12:54:20 2022 +0300
module: fix [e_shstrndx].sh_size=0 OOB access
[ Upstream commit 391e982bfa632b8315235d8be9c0a81374c6a19c ]
It is trivial to craft a module to trigger OOB access in this line:
if (info->secstrings[strhdr->sh_size - 1] != '\0') {
BUG: unable to handle page fault for address: ffffc90000aa0fff
PGD 100000067 P4D 100000067 PUD 100066067 PMD 10436f067 PTE 0
Oops: 0000 [#1] PREEMPT SMP PTI
CPU: 7 PID: 1215 Comm: insmod Not tainted 5.18.0-rc5-00007-g9bf578647087-dirty #10
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-4.fc34 04/01/2014
RIP: 0010:load_module+0x19b/0x2391
Fixes: ec2a29593c83 ("module: harden ELF info handling")
Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
[rebased patch onto modules-next]
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/module.c b/kernel/module.c
index 256b3c80a771..ef79f4dbda87 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -3029,6 +3029,10 @@ static int elf_validity_check(struct load_info *info)
* strings in the section safe.
*/
info->secstrings = (void *)info->hdr + strhdr->sh_offset;
+ if (strhdr->sh_size == 0) {
+ pr_err("empty section name table\n");
+ goto no_exec;
+ }
if (info->secstrings[strhdr->sh_size - 1] != '\0') {
pr_err("ELF Spec violation: section name table isn't null terminated\n");
goto no_exec;
