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[AX25] ax25_out: check skb for NULL in ax25_kick()
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>
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@ -117,6 +117,12 @@ void ax25_output(ax25_cb *ax25, int paclen, struct sk_buff *skb)
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unsigned char *p;
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int frontlen, len, fragno, ka9qfrag, first = 1;
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if (paclen < 16) {
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WARN_ON_ONCE(1);
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kfree_skb(skb);
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return;
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}
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if ((skb->len - 1) > paclen) {
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if (*skb->data == AX25_P_TEXT) {
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skb_pull(skb, 1); /* skip PID */
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@ -251,8 +257,6 @@ void ax25_kick(ax25_cb *ax25)
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if (start == end)
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return;
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ax25->vs = start;
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/*
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* Transmit data until either we're out of data to send or
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* the window is full. Send a poll on the final I frame if
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@ -261,8 +265,13 @@ void ax25_kick(ax25_cb *ax25)
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/*
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* Dequeue the frame and copy it.
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* Check for race with ax25_clear_queues().
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*/
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skb = skb_dequeue(&ax25->write_queue);
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if (!skb)
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return;
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ax25->vs = start;
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do {
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if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
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