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[AX25] ax25_out: check skb for NULL in ax25_kick()

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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>
This commit is contained in:
Jarek Poplawski 2008-02-17 22:31:19 -08:00 committed by David S. Miller
parent 9bf1d83e7e
commit f47b7257c7
1 changed files with 11 additions and 2 deletions
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13
net/ax25/ax25_out.c
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@ -117,6 +117,12 @@ void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
unsigned char *p; unsigned char *p;
int frontlen, len, fragno, ka9qfrag, first = 1; 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->len - 1) > paclen) {
if (*skb->data == AX25_P_TEXT) { if (*skb->data == AX25_P_TEXT) {
skb_pull(skb, 1); /* skip PID */ skb_pull(skb, 1); /* skip PID */
@ -251,8 +257,6 @@ void ax25_kick(ax25_cb *ax25)
if (start == end) if (start == end)
return; return;
ax25->vs = start;
/* /*
* Transmit data until either we're out of data to send or * 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 * 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. * Dequeue the frame and copy it.
* Check for race with ax25_clear_queues().
*/ */
skb = skb_dequeue(&ax25->write_queue); skb = skb_dequeue(&ax25->write_queue);
if (!skb)
return;
ax25->vs = start;
do { do {
if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) { if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {