[PATCH 5.10 027/120] bpf, cgroup: Fix problematic bounds check

Greg Kroah-Hartman
2021-02-08T16:58:59Z

From: Loris Reiff <loris.reiff@liblor.ch>

[ Upstream commit f4a2da755a7e1f5d845c52aee71336cee289935a ]

Since ctx.optlen is signed, a larger value than max_value could be
passed, as it is later on used as unsigned, which causes a WARN_ON_ONCE
in the copy_to_user.

Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
Signed-off-by: Loris Reiff <loris.reiff@liblor.ch>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/bpf/20210122164232.61770-2-loris.reiff@liblor.ch
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/bpf/cgroup.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c
index 6ec8f02f463b6..6aa9e10c6335a 100644
--- a/kernel/bpf/cgroup.c
+++ b/kernel/bpf/cgroup.c
@@ -1464,7 +1464,7 @@ int __cgroup_bpf_run_filter_getsockopt(struct sock *sk, int level,
goto out;
}

- if (ctx.optlen > max_optlen) {
+ if (ctx.optlen > max_optlen || ctx.optlen < 0) {
ret = -EFAULT;
goto out;
}
--
2.27.0