linux-kernel - [PATCH 3.18 066/145] xfrm_user: validate XFRM_MSG

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Message-Id: <20170416080204.104784680@linuxfoundation.org>
Date:   Sun, 16 Apr 2017 12:49:19 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andy Whitcroft <apw@...onical.com>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 3.18 066/145] xfrm_user: validate XFRM_MSG_NEWAE incoming ESN size harder

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

------------------

From: Andy Whitcroft <apw@...onical.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@...onical.com>
Acked-by: Steffen Klassert <steffen.klassert@...unet.com>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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;