From dcb7cd97f133f7cfbd181149a1e60215a869f895 Mon Sep 17 00:00:00 2001 From: Mark Huang Date: Sun, 13 Aug 2006 18:57:54 -0700 Subject: [PATCH] [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 Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- net/bridge/netfilter/ebt_ulog.c | 3 +++ net/ipv4/netfilter/ipt_ULOG.c | 5 +++++ net/netfilter/nfnetlink_log.c | 3 +++ 3 files changed, 11 insertions(+) diff --git a/net/bridge/netfilter/ebt_ulog.c b/net/bridge/netfilter/ebt_ulog.c index 02693a230dc1..9f950db3b76f 100644 --- a/net/bridge/netfilter/ebt_ulog.c +++ b/net/bridge/netfilter/ebt_ulog.c @@ -74,6 +74,9 @@ static void ulog_send(unsigned int nlgroup) if (timer_pending(&ub->timer)) del_timer(&ub->timer); + if (!ub->skb) + return; + /* last nlmsg needs NLMSG_DONE */ if (ub->qlen > 1) ub->lastnlh->nlmsg_type = NLMSG_DONE; diff --git a/net/ipv4/netfilter/ipt_ULOG.c b/net/ipv4/netfilter/ipt_ULOG.c index d7dd7fe7051c..d46fd677fa11 100644 --- a/net/ipv4/netfilter/ipt_ULOG.c +++ b/net/ipv4/netfilter/ipt_ULOG.c @@ -115,6 +115,11 @@ static void ulog_send(unsigned int nlgroupnum) del_timer(&ub->timer); } + if (!ub->skb) { + DEBUGP("ipt_ULOG: ulog_send: nothing to send\n"); + return; + } + /* last nlmsg needs NLMSG_DONE */ if (ub->qlen > 1) ub->lastnlh->nlmsg_type = NLMSG_DONE; diff --git a/net/netfilter/nfnetlink_log.c b/net/netfilter/nfnetlink_log.c index 61cdda4e5d3b..b59d3b2bde21 100644 --- a/net/netfilter/nfnetlink_log.c +++ b/net/netfilter/nfnetlink_log.c @@ -366,6 +366,9 @@ __nfulnl_send(struct nfulnl_instance *inst) if (timer_pending(&inst->timer)) del_timer(&inst->timer); + if (!inst->skb) + return 0; + if (inst->qlen > 1) inst->lastnlh->nlmsg_type = NLMSG_DONE; -- 2.20.1