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authorEric Dumazet <eric.dumazet@gmail.com>2011-08-22 19:32:42 +0000
committerDavid S. Miller <davem@davemloft.net>2011-08-24 17:55:00 -0700
commit20e6074eb8e096b3a595c093d1cb222f378cd671 (patch)
tree1aef2b6e39cb3cb607213625c2bae75b9cc97ab1 /net
parent22df13319d1fec30b8f9bcaadc295829647109bb (diff)
downloadlinux-linaro-stable-20e6074eb8e096b3a595c093d1cb222f378cd671.tar.gz
arp: fix rcu lockdep splat in arp_process()
Dave Jones reported a lockdep splat triggered by an arp_process() call from parp_redo(). Commit faa9dcf793be (arp: RCU changes) is the origin of the bug, since it assumed arp_process() was called under rcu_read_lock(), which is not true in this particular path. Instead of adding rcu_read_lock() in parp_redo(), I chose to add it in neigh_proxy_process() to take care of IPv6 side too. =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- include/linux/inetdevice.h:209 invoked rcu_dereference_check() without protection! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 0 4 locks held by setfiles/2123: #0: (&sb->s_type->i_mutex_key#13){+.+.+.}, at: [<ffffffff8114cbc4>] walk_component+0x1ef/0x3e8 #1: (&isec->lock){+.+.+.}, at: [<ffffffff81204bca>] inode_doinit_with_dentry+0x3f/0x41f #2: (&tbl->proxy_timer){+.-...}, at: [<ffffffff8106a803>] run_timer_softirq+0x157/0x372 #3: (class){+.-...}, at: [<ffffffff8141f256>] neigh_proxy_process +0x36/0x103 stack backtrace: Pid: 2123, comm: setfiles Tainted: G W 3.1.0-0.rc2.git7.2.fc16.x86_64 #1 Call Trace: <IRQ> [<ffffffff8108ca23>] lockdep_rcu_dereference+0xa7/0xaf [<ffffffff8146a0b7>] __in_dev_get_rcu+0x55/0x5d [<ffffffff8146a751>] arp_process+0x25/0x4d7 [<ffffffff8146ac11>] parp_redo+0xe/0x10 [<ffffffff8141f2ba>] neigh_proxy_process+0x9a/0x103 [<ffffffff8106a8c4>] run_timer_softirq+0x218/0x372 [<ffffffff8106a803>] ? run_timer_softirq+0x157/0x372 [<ffffffff8141f220>] ? neigh_stat_seq_open+0x41/0x41 [<ffffffff8108f2f0>] ? mark_held_locks+0x6d/0x95 [<ffffffff81062bb6>] __do_softirq+0x112/0x25a [<ffffffff8150d27c>] call_softirq+0x1c/0x30 [<ffffffff81010bf5>] do_softirq+0x4b/0xa2 [<ffffffff81062f65>] irq_exit+0x5d/0xcf [<ffffffff8150dc11>] smp_apic_timer_interrupt+0x7c/0x8a [<ffffffff8150baf3>] apic_timer_interrupt+0x73/0x80 <EOI> [<ffffffff8108f439>] ? trace_hardirqs_on_caller+0x121/0x158 [<ffffffff814fc285>] ? __slab_free+0x30/0x24c [<ffffffff814fc283>] ? __slab_free+0x2e/0x24c [<ffffffff81204e74>] ? inode_doinit_with_dentry+0x2e9/0x41f [<ffffffff81204e74>] ? inode_doinit_with_dentry+0x2e9/0x41f [<ffffffff81204e74>] ? inode_doinit_with_dentry+0x2e9/0x41f [<ffffffff81130cb0>] kfree+0x108/0x131 [<ffffffff81204e74>] inode_doinit_with_dentry+0x2e9/0x41f [<ffffffff81204fc6>] selinux_d_instantiate+0x1c/0x1e [<ffffffff81200f4f>] security_d_instantiate+0x21/0x23 [<ffffffff81154625>] d_instantiate+0x5c/0x61 [<ffffffff811563ca>] d_splice_alias+0xbc/0xd2 [<ffffffff811b17ff>] ext4_lookup+0xba/0xeb [<ffffffff8114bf1e>] d_alloc_and_lookup+0x45/0x6b [<ffffffff8114cbea>] walk_component+0x215/0x3e8 [<ffffffff8114cdf8>] lookup_last+0x3b/0x3d [<ffffffff8114daf3>] path_lookupat+0x82/0x2af [<ffffffff8110fc53>] ? might_fault+0xa5/0xac [<ffffffff8110fc0a>] ? might_fault+0x5c/0xac [<ffffffff8114c564>] ? getname_flags+0x31/0x1ca [<ffffffff8114dd48>] do_path_lookup+0x28/0x97 [<ffffffff8114df2c>] user_path_at+0x59/0x96 [<ffffffff811467ad>] ? cp_new_stat+0xf7/0x10d [<ffffffff811469a6>] vfs_fstatat+0x44/0x6e [<ffffffff811469ee>] vfs_lstat+0x1e/0x20 [<ffffffff81146b3d>] sys_newlstat+0x1a/0x33 [<ffffffff8108f439>] ? trace_hardirqs_on_caller+0x121/0x158 [<ffffffff812535fe>] ? trace_hardirqs_on_thunk+0x3a/0x3f [<ffffffff8150af82>] system_call_fastpath+0x16/0x1b Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/core/neighbour.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 8fab9b0bb203..1334d7e56f02 100644
--- a/net/core/neighbour.c
+++ b/net/core/neighbour.c
@@ -1319,11 +1319,15 @@ static void neigh_proxy_process(unsigned long arg)
if (tdif <= 0) {
struct net_device *dev = skb->dev;
+
__skb_unlink(skb, &tbl->proxy_queue);
- if (tbl->proxy_redo && netif_running(dev))
+ if (tbl->proxy_redo && netif_running(dev)) {
+ rcu_read_lock();
tbl->proxy_redo(skb);
- else
+ rcu_read_unlock();
+ } else {
kfree_skb(skb);
+ }
dev_put(dev);
} else if (!sched_next || tdif < sched_next)