Messages in this thread Patch in this message | | | Date | Wed, 16 Apr 2008 18:01:50 -0700 | From | Chris Wright <> | Subject | AX25 ax25_out: check skb for NULL in ax25_kick() |
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-stable review patch. If anyone has any objections, please let us know. ---------------------
From: Jarek Poplawski <jarkao2@gmail.com>
Upstream commit: f47b7257c7368698eabff6fd7b340071932af640
According to some OOPS reports ax25_kick tries to clone NULL skbs sometimes. It looks like a race with ax25_clear_queues(). Probably there is no need to add more than a simple check for this yet. Another report suggested there are probably also cases where ax25 ->paclen == 0 can happen in ax25_output(); this wasn't confirmed during testing but let's leave this debugging check for some time.
Reported-and-tested-by: Jann Traschewski <jann@gmx.de> Signed-off-by: Jarek Poplawski <jarkao2@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Chris Wright <chrisw@sous-sol.org> --- net/ax25/ax25_out.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
--- a/net/ax25/ax25_out.c +++ b/net/ax25/ax25_out.c @@ -117,6 +117,12 @@ void ax25_output(ax25_cb *ax25, int pacl unsigned char *p; int frontlen, len, fragno, ka9qfrag, first = 1; + if (paclen < 16) { + WARN_ON_ONCE(1); + kfree_skb(skb); + return; + } + if ((skb->len - 1) > paclen) { if (*skb->data == AX25_P_TEXT) { skb_pull(skb, 1); /* skip PID */ @@ -251,8 +257,6 @@ void ax25_kick(ax25_cb *ax25) if (start == end) return; - ax25->vs = start; - /* * Transmit data until either we're out of data to send or * the window is full. Send a poll on the final I frame if @@ -261,8 +265,13 @@ void ax25_kick(ax25_cb *ax25) /* * Dequeue the frame and copy it. + * Check for race with ax25_clear_queues(). */ skb = skb_dequeue(&ax25->write_queue); + if (!skb) + return; + + ax25->vs = start; do { if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { --
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