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Subject[049/107] x25: Prevent skb overreads when checking call user data
2.6.32-longterm review patch.  If anyone has any objections, please let us know.

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

From: Matthew Daley <mattjd@gmail.com>

commit 7f81e25befdfb3272345a2e775f520e1d515fa20 upstream.

x25_find_listener does not check that the amount of call user data given
in the skb is big enough in per-socket comparisons, hence buffer
overreads may occur. Fix this by adding a check.

Signed-off-by: Matthew Daley <mattjd@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Andrew Hendry <andrew.hendry@gmail.com>
Acked-by: Andrew Hendry <andrew.hendry@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
net/x25/af_x25.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/net/x25/af_x25.c
+++ b/net/x25/af_x25.c
@@ -294,7 +294,8 @@ static struct sock *x25_find_listener(st
* Found a listening socket, now check the incoming
* call user data vs this sockets call user data
*/
- if(skb->len > 0 && x25_sk(s)->cudmatchlength > 0) {
+ if (x25_sk(s)->cudmatchlength > 0 &&
+ skb->len >= x25_sk(s)->cudmatchlength) {
if((memcmp(x25_sk(s)->calluserdata.cuddata,
skb->data,
x25_sk(s)->cudmatchlength)) == 0) {



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