Patch "net: llc: fix use after free in llc_ui_recvmsg" has been added to the 3.10-stable tree

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

    net: llc: fix use after free in llc_ui_recvmsg

to the 3.10-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:
     net-llc-fix-use-after-free-in-llc_ui_recvmsg.patch
and it can be found in the queue-3.10 subdirectory.

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


>From foo@baz Mon Jan 13 09:39:01 PST 2014
From: Daniel Borkmann <dborkman@xxxxxxxxxx>
Date: Mon, 30 Dec 2013 23:40:50 +0100
Subject: net: llc: fix use after free in llc_ui_recvmsg

From: Daniel Borkmann <dborkman@xxxxxxxxxx>

[ Upstream commit 4d231b76eef6c4a6bd9c96769e191517765942cb ]

While commit 30a584d944fb fixes datagram interface in LLC, a use
after free bug has been introduced for SOCK_STREAM sockets that do
not make use of MSG_PEEK.

The flow is as follow ...

  if (!(flags & MSG_PEEK)) {
    ...
    sk_eat_skb(sk, skb, false);
    ...
  }
  ...
  if (used + offset < skb->len)
    continue;

... where sk_eat_skb() calls __kfree_skb(). Therefore, cache
original length and work on skb_len to check partial reads.

Fixes: 30a584d944fb ("[LLX]: SOCK_DGRAM interface fixes")
Signed-off-by: Daniel Borkmann <dborkman@xxxxxxxxxx>
Cc: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/llc/af_llc.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -715,7 +715,7 @@ static int llc_ui_recvmsg(struct kiocb *
 	unsigned long cpu_flags;
 	size_t copied = 0;
 	u32 peek_seq = 0;
-	u32 *seq;
+	u32 *seq, skb_len;
 	unsigned long used;
 	int target;	/* Read at least this many bytes */
 	long timeo;
@@ -812,6 +812,7 @@ static int llc_ui_recvmsg(struct kiocb *
 		}
 		continue;
 	found_ok_skb:
+		skb_len = skb->len;
 		/* Ok so how much can we use? */
 		used = skb->len - offset;
 		if (len < used)
@@ -844,7 +845,7 @@ static int llc_ui_recvmsg(struct kiocb *
 		}
 
 		/* Partial read */
-		if (used + offset < skb->len)
+		if (used + offset < skb_len)
 			continue;
 	} while (len > 0);
 


Patches currently in stable-queue which might be from dborkman@xxxxxxxxxx are

queue-3.10/net-inet_diag-zero-out-uninitialized-idiag_-src-dst-fields.patch
queue-3.10/packet-fix-send-path-when-running-with-proto-0.patch
queue-3.10/net-llc-fix-use-after-free-in-llc_ui_recvmsg.patch
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