[PATCH 3.18 066/145] xfrm_user: validate XFRM_MSG_NEWAE incoming ESN size harder

Greg Kroah-Hartman
2017-04-16T10:54:25Z

From: Andy Whitcroft <apw@canonical.com>

commit f843ee6dd019bcece3e74e76ad9df0155655d0df upstream.

Kees Cook has pointed out that xfrm_replay_state_esn_len() is subject to
wrapping issues. To ensure we are correctly ensuring that the two ESN
structures are the same size compare both the overall size as reported
by xfrm_replay_state_esn_len() and the internal length are the same.

CVE-2017-7184
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/xfrm/xfrm_user.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -386,7 +386,11 @@ static inline int xfrm_replay_verify_len
up = nla_data(rp);
ulen = xfrm_replay_state_esn_len(up);

- if (nla_len(rp) < ulen || xfrm_replay_state_esn_len(replay_esn) != ulen)
+ /* Check the overall length and the internal bitmap length to avoid
+ * potential overflow. */
+ if (nla_len(rp) < ulen ||
+ xfrm_replay_state_esn_len(replay_esn) != ulen ||
+ replay_esn->bmp_len != up->bmp_len)
return -EINVAL;

return 0;