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Message-ID: <1314077562.4791.21.camel@edumazet-laptop>
Date: Tue, 23 Aug 2011 07:32:42 +0200
From: Eric Dumazet <eric.dumazet@...il.com>
To: Dave Jones <davej@...hat.com>, David Miller <davem@...emloft.net>
Cc: netdev@...r.kernel.org
Subject: Re: (3.1.0-rc2-git7) include/linux/inetdevice.h:209 invoked
rcu_dereference_check() without protection!
Le lundi 22 août 2011 à 22:44 -0400, Dave Jones a écrit :
> Just hit this..
> Is the fix as straight forward as changing that __in_dev_get_rcu to
> an in_dev_get() ?
>
> Dave
>
>
> ===================================================
> [ 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
>
Dave, thanks again for your report, here the fix I cooked to address
this.
Kernels >= 2.6.36 are affected, probably only RT ones, since
neigh_proxy_process() holds a spinlock before the call to proxy_redo().
David, IPv6 side is affected too only in net-next, but following patch
should take care of both protocols.
Thanks
[PATCH] 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@...hat.com>
Signed-off-by: Eric Dumazet <eric.dumazet@...il.com>
---
net/core/neighbour.c | 8 ++++++--
1 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c
index 8fab9b0..1334d7e 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)
--
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