[NETFILTER]: ulog: fix panic on SMP kernels
Fix kernel panic on various SMP machines. The culprit is a null ub->skb in ulog_send(). If ulog_timer() has already been scheduled on one CPU and is spinning on the lock, and ipt_ulog_packet() flushes the queue on another CPU by calling ulog_send() right before it exits, there will be no skbuff when ulog_timer() acquires the lock and calls ulog_send(). Cancelling the timer in ulog_send() doesn't help because it has already been scheduled and is running on the first CPU. Similar problem exists in ebt_ulog.c and nfnetlink_log.c. Signed-off-by: Mark Huang <mlhuang@cs.princeton.edu> Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
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@ -74,6 +74,9 @@ static void ulog_send(unsigned int nlgroup)
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if (timer_pending(&ub->timer))
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del_timer(&ub->timer);
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if (!ub->skb)
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return;
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/* last nlmsg needs NLMSG_DONE */
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if (ub->qlen > 1)
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ub->lastnlh->nlmsg_type = NLMSG_DONE;
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@ -115,6 +115,11 @@ static void ulog_send(unsigned int nlgroupnum)
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del_timer(&ub->timer);
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}
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if (!ub->skb) {
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DEBUGP("ipt_ULOG: ulog_send: nothing to send\n");
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return;
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}
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/* last nlmsg needs NLMSG_DONE */
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if (ub->qlen > 1)
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ub->lastnlh->nlmsg_type = NLMSG_DONE;
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@ -366,6 +366,9 @@ __nfulnl_send(struct nfulnl_instance *inst)
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if (timer_pending(&inst->timer))
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del_timer(&inst->timer);
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if (!inst->skb)
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return 0;
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if (inst->qlen > 1)
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inst->lastnlh->nlmsg_type = NLMSG_DONE;
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