Patch "xfrm_user: uncoditionally validate esn replay attribute struct" has been added to the 4.15-stable tree

Patch "xfrm_user: uncoditionally validate esn replay attribute struct" has been added to the 4.15-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    xfrm_user: uncoditionally validate esn replay attribute struct

to the 4.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     xfrm_user-uncoditionally-validate-esn-replay-attribute-struct.patch
and it can be found in the queue-4.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From d97ca5d714a5334aecadadf696875da40f1fbf3e Mon Sep 17 00:00:00 2001
From: Florian Westphal <fw@strlen.de>
Date: Mon, 12 Feb 2018 14:42:01 +0100
Subject: xfrm_user: uncoditionally validate esn replay attribute struct

From: Florian Westphal <fw@strlen.de>

commit d97ca5d714a5334aecadadf696875da40f1fbf3e upstream.

The sanity test added in ecd7918745234 can be bypassed, validation
only occurs if XFRM_STATE_ESN flag is set, but rest of code doesn't care
and just checks if the attribute itself is present.

So always validate.  Alternative is to reject if we have the attribute
without the flag but that would change abi.

Reported-by: syzbot+0ab777c27d2bb7588f73@syzkaller.appspotmail.com
Cc: Mathias Krause <minipli@googlemail.com>
Fixes: ecd7918745234 ("xfrm_user: ensure user supplied esn replay window is valid")
Fixes: d8647b79c3b7e ("xfrm: Add user interface for esn and big anti-replay windows")
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/xfrm/xfrm_user.c |   21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -121,22 +121,17 @@ static inline int verify_replay(struct x
 	struct nlattr *rt = attrs[XFRMA_REPLAY_ESN_VAL];
 	struct xfrm_replay_state_esn *rs;
 
-	if (p->flags & XFRM_STATE_ESN) {
-		if (!rt)
-			return -EINVAL;
-
-		rs = nla_data(rt);
+	if (!rt)
+		return (p->flags & XFRM_STATE_ESN) ? -EINVAL : 0;
 
-		if (rs->bmp_len > XFRMA_REPLAY_ESN_MAX / sizeof(rs->bmp[0]) / 8)
-			return -EINVAL;
+	rs = nla_data(rt);
 
-		if (nla_len(rt) < (int)xfrm_replay_state_esn_len(rs) &&
-		    nla_len(rt) != sizeof(*rs))
-			return -EINVAL;
-	}
+	if (rs->bmp_len > XFRMA_REPLAY_ESN_MAX / sizeof(rs->bmp[0]) / 8)
+		return -EINVAL;
 
-	if (!rt)
-		return 0;
+	if (nla_len(rt) < (int)xfrm_replay_state_esn_len(rs) &&
+	    nla_len(rt) != sizeof(*rs))
+		return -EINVAL;
 
 	/* As only ESP and AH support ESN feature. */
 	if ((p->id.proto != IPPROTO_ESP) && (p->id.proto != IPPROTO_AH))


Patches currently in stable-queue which might be from fw@strlen.de are

queue-4.15/xfrm_user-uncoditionally-validate-esn-replay-attribute-struct.patch