From a7e64e932bfd3423495441c6956410fe1e96f453 Mon Sep 17 00:00:00 2001 From: Jarek Poplawski Date: Tue, 3 Jun 2008 14:53:46 -0700 Subject: [PATCH] ax25: Fix NULL pointer dereference and lockup. From: Jarek Poplawski There is only one function in AX25 calling skb_append(), and it really looks suspicious: appends skb after previously enqueued one, but in the meantime this previous skb could be removed from the queue. This patch Fixes it the simple way, so this is not fully compatible with the current method, but testing hasn't shown any problems. Signed-off-by: Ralf Baechle Signed-off-by: David S. Miller --- net/ax25/ax25_subr.c | 11 +++-------- 1 file changed, 3 insertions(+), 8 deletions(-) diff --git a/net/ax25/ax25_subr.c b/net/ax25/ax25_subr.c index d8f2157331757..034aa10a5198b 100644 --- a/net/ax25/ax25_subr.c +++ b/net/ax25/ax25_subr.c @@ -64,20 +64,15 @@ void ax25_frames_acked(ax25_cb *ax25, unsigned short nr) void ax25_requeue_frames(ax25_cb *ax25) { - struct sk_buff *skb, *skb_prev = NULL; + struct sk_buff *skb; /* * Requeue all the un-ack-ed frames on the output queue to be picked * up by ax25_kick called from the timer. This arrangement handles the * possibility of an empty output queue. */ - while ((skb = skb_dequeue(&ax25->ack_queue)) != NULL) { - if (skb_prev == NULL) - skb_queue_head(&ax25->write_queue, skb); - else - skb_append(skb_prev, skb, &ax25->write_queue); - skb_prev = skb; - } + while ((skb = skb_dequeue_tail(&ax25->ack_queue)) != NULL) + skb_queue_head(&ax25->write_queue, skb); } /* -- 2.39.5