diff options
| author | roy.qing.li@gmail.com <roy.qing.li@gmail.com> | 2011-10-17 22:32:42 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2011-10-19 19:38:51 -0400 |
| commit | e049f28883126c689cf95859480d9ee4ab23b7fa (patch) | |
| tree | e11981b829f84984d7dc80337d1b7926a24c3cee | |
| parent | 4f25af27827080c3163e59c7af1ca84a05ce121c (diff) | |
neigh: fix rcu splat in neigh_update()
when use dst_get_neighbour to get neighbour, we need
rcu_read_lock to protect, since dst_get_neighbour uses
rcu_dereference.
The bug was reported by Ari Savolainen <ari.m.savolainen@gmail.com>
[ 105.612095]
[ 105.612096] ===================================================
[ 105.612100] [ INFO: suspicious rcu_dereference_check() usage. ]
[ 105.612101] ---------------------------------------------------
[ 105.612103] include/net/dst.h:91 invoked rcu_dereference_check()
without protection!
[ 105.612105]
[ 105.612106] other info that might help us debug this:
[ 105.612106]
[ 105.612108]
[ 105.612108] rcu_scheduler_active = 1, debug_locks = 0
[ 105.612110] 1 lock held by dnsmasq/2618:
[ 105.612111] #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff815df8c7>]
rtnl_lock+0x17/0x20
[ 105.612120]
[ 105.612121] stack backtrace:
[ 105.612123] Pid: 2618, comm: dnsmasq Not tainted 3.1.0-rc1 #41
[ 105.612125] Call Trace:
[ 105.612129] [<ffffffff810ccdcb>] lockdep_rcu_dereference+0xbb/0xc0
[ 105.612132] [<ffffffff815dc5a9>] neigh_update+0x4f9/0x5f0
[ 105.612135] [<ffffffff815da001>] ? neigh_lookup+0xe1/0x220
[ 105.612139] [<ffffffff81639298>] arp_req_set+0xb8/0x230
[ 105.612142] [<ffffffff8163a59f>] arp_ioctl+0x1bf/0x310
[ 105.612146] [<ffffffff810baa40>] ? lock_hrtimer_base.isra.26+0x30/0x60
[ 105.612150] [<ffffffff8163fb75>] inet_ioctl+0x85/0x90
[ 105.612154] [<ffffffff815b5520>] sock_do_ioctl+0x30/0x70
[ 105.612157] [<ffffffff815b55d3>] sock_ioctl+0x73/0x280
[ 105.612162] [<ffffffff811b7698>] do_vfs_ioctl+0x98/0x570
[ 105.612165] [<ffffffff811a5c40>] ? fget_light+0x340/0x3a0
[ 105.612168] [<ffffffff811b7bbf>] sys_ioctl+0x4f/0x80
[ 105.612172] [<ffffffff816fdcab>] system_call_fastpath+0x16/0x1b
Reported-by: Ari Savolainen <ari.m.savolainen@gmail.com>
Signed-off-by: RongQing <roy.qing.li@gmail.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/core/neighbour.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 43449649cf73..909ecb3c2a33 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -1168,10 +1168,14 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new, struct dst_entry *dst = skb_dst(skb); struct neighbour *n2, *n1 = neigh; write_unlock_bh(&neigh->lock); + + rcu_read_lock(); /* On shaper/eql skb->dst->neighbour != neigh :( */ if (dst && (n2 = dst_get_neighbour(dst)) != NULL) n1 = n2; n1->output(n1, skb); + rcu_read_unlock(); + write_lock_bh(&neigh->lock); } skb_queue_purge(&neigh->arp_queue); |