NFC: Fix incorrect llcp pointer dereference

nfc_llcp_ns(s) dereferences the s pointer which is freed a line
above. In a result, it can produce a crash or you will read
incorrect value.

Signed-off-by: Waldemar Rymarkiewicz <waldemar.rymarkiewicz@tieto.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/net/nfc/llcp/llcp.c b/net/nfc/llcp/llcp.c
index 9e8f4b2801f6..3d63636120b1 100644
--- a/net/nfc/llcp/llcp.c
+++ b/net/nfc/llcp/llcp.c
@@ -903,15 +903,18 @@ static void nfc_llcp_recv_hdlc(struct nfc_llcp_local *local,
         /* Remove skbs from the pending queue */
         if (llcp_sock->send_ack_n != nr) {
                 struct sk_buff *s, *tmp;
+                u8 n;
 
                 llcp_sock->send_ack_n = nr;
 
                 /* Remove and free all skbs until ns == nr */
                 skb_queue_walk_safe(&llcp_sock->tx_pending_queue, s, tmp) {
+                        n = nfc_llcp_ns(s);
+
                         skb_unlink(s, &llcp_sock->tx_pending_queue);
                         kfree_skb(s);
 
-                        if (nfc_llcp_ns(s) == nr)
+                        if (n == nr)
                                 break;
                 }