From: Alexey Dobriyan adobriyan@gmail.com
[ 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@gmail.com [rebased patch onto modules-next] Signed-off-by: Luis Chamberlain mcgrof@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/module.c | 4 ++++ 1 file changed, 4 insertions(+)
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;