llc: llc_cmsg_rcv was getting called after sk_eat_skb.

Received non stream protocol packets were calling llc_cmsg_rcv that used a
skb after that skb was released by sk_eat_skb. This caused received STP
packets to generate kernel panics.

Signed-off-by: Alexandru Juncu <ajuncu@ixiacom.com>
Signed-off-by: Kunjan Naik <knaik@ixiacom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 4 deletions

diff --git a/net/llc/af_llc.c b/net/llc/af_llc.c
index dfd3a648a551..a18e6c3d36e3 100644
--- a/net/llc/af_llc.c
+++ b/net/llc/af_llc.c
@@ -833,15 +833,15 @@ static int llc_ui_recvmsg(struct kiocb *iocb, struct socket *sock,
                 copied += used;
                 len -= used;
 
+                /* For non stream protcols we get one packet per recvmsg call */
+                if (sk->sk_type != SOCK_STREAM)
+                        goto copy_uaddr;
+
                 if (!(flags & MSG_PEEK)) {
                         sk_eat_skb(sk, skb, 0);
                         *seq = 0;
                 }
 
-                /* For non stream protcols we get one packet per recvmsg call */
-                if (sk->sk_type != SOCK_STREAM)
-                        goto copy_uaddr;
-
                 /* Partial read */
                 if (used + offset < skb->len)
                         continue;
@@ -857,6 +857,12 @@ copy_uaddr:
         }
         if (llc_sk(sk)->cmsg_flags)
                 llc_cmsg_rcv(msg, skb);
+
+        if (!(flags & MSG_PEEK)) {
+                        sk_eat_skb(sk, skb, 0);
+                        *seq = 0;
+        }
+
         goto out;
 }