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Subject[PATCH 3.12 102/142] xfrm_user: validate XFRM_MSG_NEWAE incoming ESN size harder
Date
From: Andy Whitcroft <apw@canonical.com>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

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: Jiri Slaby <jslaby@suse.cz>
---
net/xfrm/xfrm_user.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 9a6bd448468d..52fe9a77a1b1 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -390,7 +390,11 @@ static inline int xfrm_replay_verify_len(struct xfrm_replay_state_esn *replay_es
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;

if (up->replay_window > up->bmp_len * sizeof(__u32) * 8)
--
2.12.2
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