* [PATCH net] vxlan: add missing rcu_read_lock() in neigh_reduce()
@ 2021-06-21 14:44 Eric Dumazet
2021-06-21 16:04 ` Daniel Borkmann
2021-06-22 16:50 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 4+ messages in thread
From: Eric Dumazet @ 2021-06-21 14:44 UTC (permalink / raw)
To: David S . Miller, Jakub Kicinski
Cc: netdev, Eric Dumazet, Eric Dumazet, syzbot
From: Eric Dumazet <edumazet@google.com>
syzbot complained in neigh_reduce(), because rcu_read_lock_bh()
is treated differently than rcu_read_lock()
WARNING: suspicious RCU usage
5.13.0-rc6-syzkaller #0 Not tainted
-----------------------------
include/net/addrconf.h:313 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
3 locks held by kworker/0:0/5:
#0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
#0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
#0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:617 [inline]
#0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
#0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2247
#1: ffffc90000ca7da8 ((work_completion)(&port->wq)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2251
#2: ffffffff8bf795c0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1da/0x3130 net/core/dev.c:4180
stack backtrace:
CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.13.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events ipvlan_process_multicast
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
__in6_dev_get include/net/addrconf.h:313 [inline]
__in6_dev_get include/net/addrconf.h:311 [inline]
neigh_reduce drivers/net/vxlan.c:2167 [inline]
vxlan_xmit+0x34d5/0x4c30 drivers/net/vxlan.c:2919
__netdev_start_xmit include/linux/netdevice.h:4944 [inline]
netdev_start_xmit include/linux/netdevice.h:4958 [inline]
xmit_one net/core/dev.c:3654 [inline]
dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3670
__dev_queue_xmit+0x2133/0x3130 net/core/dev.c:4246
ipvlan_process_multicast+0xa99/0xd70 drivers/net/ipvlan/ipvlan_core.c:287
process_one_work+0x98d/0x1600 kernel/workqueue.c:2276
worker_thread+0x64c/0x1120 kernel/workqueue.c:2422
kthread+0x3b1/0x4a0 kernel/kthread.c:313
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
Fixes: f564f45c4518 ("vxlan: add ipv6 proxy support")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
---
drivers/net/vxlan.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 02a14f1b938ad50fc28044b7670ba5f6bf924345..5a8df5a195cb5700c45b4785355ef8ed84866052 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2164,6 +2164,7 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni)
struct neighbour *n;
struct nd_msg *msg;
+ rcu_read_lock();
in6_dev = __in6_dev_get(dev);
if (!in6_dev)
goto out;
@@ -2215,6 +2216,7 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni)
}
out:
+ rcu_read_unlock();
consume_skb(skb);
return NETDEV_TX_OK;
}
--
2.32.0.288.g62a8d224e6-goog
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH net] vxlan: add missing rcu_read_lock() in neigh_reduce()
2021-06-21 14:44 [PATCH net] vxlan: add missing rcu_read_lock() in neigh_reduce() Eric Dumazet
@ 2021-06-21 16:04 ` Daniel Borkmann
2021-06-21 18:27 ` Paul E. McKenney
2021-06-22 16:50 ` patchwork-bot+netdevbpf
1 sibling, 1 reply; 4+ messages in thread
From: Daniel Borkmann @ 2021-06-21 16:04 UTC (permalink / raw)
To: Eric Dumazet, David S . Miller, Jakub Kicinski
Cc: netdev, Eric Dumazet, syzbot, paulmck, toke, ast
On 6/21/21 4:44 PM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> syzbot complained in neigh_reduce(), because rcu_read_lock_bh()
> is treated differently than rcu_read_lock()
>
> WARNING: suspicious RCU usage
> 5.13.0-rc6-syzkaller #0 Not tainted
> -----------------------------
> include/net/addrconf.h:313 suspicious rcu_dereference_check() usage!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 3 locks held by kworker/0:0/5:
> #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
> #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
> #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
> #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:617 [inline]
> #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
> #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2247
> #1: ffffc90000ca7da8 ((work_completion)(&port->wq)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2251
> #2: ffffffff8bf795c0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1da/0x3130 net/core/dev.c:4180
>
> stack backtrace:
> CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.13.0-rc6-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> Workqueue: events ipvlan_process_multicast
> Call Trace:
> __dump_stack lib/dump_stack.c:79 [inline]
> dump_stack+0x141/0x1d7 lib/dump_stack.c:120
> __in6_dev_get include/net/addrconf.h:313 [inline]
> __in6_dev_get include/net/addrconf.h:311 [inline]
> neigh_reduce drivers/net/vxlan.c:2167 [inline]
> vxlan_xmit+0x34d5/0x4c30 drivers/net/vxlan.c:2919
> __netdev_start_xmit include/linux/netdevice.h:4944 [inline]
> netdev_start_xmit include/linux/netdevice.h:4958 [inline]
> xmit_one net/core/dev.c:3654 [inline]
> dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3670
> __dev_queue_xmit+0x2133/0x3130 net/core/dev.c:4246
> ipvlan_process_multicast+0xa99/0xd70 drivers/net/ipvlan/ipvlan_core.c:287
> process_one_work+0x98d/0x1600 kernel/workqueue.c:2276
> worker_thread+0x64c/0x1120 kernel/workqueue.c:2422
> kthread+0x3b1/0x4a0 kernel/kthread.c:313
> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
>
> Fixes: f564f45c4518 ("vxlan: add ipv6 proxy support")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reported-by: syzbot <syzkaller@googlegroups.com>
[ +Paul/Toke ]
Only a side comment on this fix given the series under [0] where we remove the
rcu_read_lock() given covered by rcu_read_lock_bh():
[...] It seems [1] that back in the early days of XDP, local_bh_disable() did
not provide RCU protection, which is why the rcu_read_lock() calls were added
to drivers in the first place. But according to Paul [2], in recent kernels
a local_bh_disable()/local_bh_enable() pair functions as one big RCU
read-side section, so no further protection is needed. This even applies to
-rt kernels, which has an explicit rcu_read_lock() in place as part of the
local_bh_disable() [3]. [...]
Paul/Toke, with regards to related questions under [1], I presume there should
additionally be a fixup for lockdep /in general/ to silence warning like these ?
[0] https://lore.kernel.org/bpf/20210617212748.32456-1-toke@redhat.com/
[1] https://lore.kernel.org/bpf/1881ecbe-06ec-6b0a-836c-033c31fabef4@iogearbox.net/
> ---
> drivers/net/vxlan.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
> index 02a14f1b938ad50fc28044b7670ba5f6bf924345..5a8df5a195cb5700c45b4785355ef8ed84866052 100644
> --- a/drivers/net/vxlan.c
> +++ b/drivers/net/vxlan.c
> @@ -2164,6 +2164,7 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni)
> struct neighbour *n;
> struct nd_msg *msg;
>
> + rcu_read_lock();
> in6_dev = __in6_dev_get(dev);
> if (!in6_dev)
> goto out;
> @@ -2215,6 +2216,7 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni)
> }
>
> out:
> + rcu_read_unlock();
> consume_skb(skb);
> return NETDEV_TX_OK;
> }
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH net] vxlan: add missing rcu_read_lock() in neigh_reduce()
2021-06-21 16:04 ` Daniel Borkmann
@ 2021-06-21 18:27 ` Paul E. McKenney
0 siblings, 0 replies; 4+ messages in thread
From: Paul E. McKenney @ 2021-06-21 18:27 UTC (permalink / raw)
To: Daniel Borkmann
Cc: Eric Dumazet, David S . Miller, Jakub Kicinski, netdev,
Eric Dumazet, syzbot, toke, ast
On Mon, Jun 21, 2021 at 06:04:46PM +0200, Daniel Borkmann wrote:
> On 6/21/21 4:44 PM, Eric Dumazet wrote:
> > From: Eric Dumazet <edumazet@google.com>
> >
> > syzbot complained in neigh_reduce(), because rcu_read_lock_bh()
> > is treated differently than rcu_read_lock()
> >
> > WARNING: suspicious RCU usage
> > 5.13.0-rc6-syzkaller #0 Not tainted
> > -----------------------------
> > include/net/addrconf.h:313 suspicious rcu_dereference_check() usage!
> >
> > other info that might help us debug this:
> >
> > rcu_scheduler_active = 2, debug_locks = 1
This "debug_locks = 1" often indicates that there was some other lockdep
complaint that happened at about the same time.
> > 3 locks held by kworker/0:0/5:
> > #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
> > #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline]
> > #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline]
> > #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:617 [inline]
> > #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
> > #0: ffff888011064d38 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x871/0x1600 kernel/workqueue.c:2247
> > #1: ffffc90000ca7da8 ((work_completion)(&port->wq)){+.+.}-{0:0}, at: process_one_work+0x8a5/0x1600 kernel/workqueue.c:2251
> > #2: ffffffff8bf795c0 (rcu_read_lock_bh){....}-{1:2}, at: __dev_queue_xmit+0x1da/0x3130 net/core/dev.c:4180
> >
> > stack backtrace:
> > CPU: 0 PID: 5 Comm: kworker/0:0 Not tainted 5.13.0-rc6-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> > Workqueue: events ipvlan_process_multicast
> > Call Trace:
> > __dump_stack lib/dump_stack.c:79 [inline]
> > dump_stack+0x141/0x1d7 lib/dump_stack.c:120
> > __in6_dev_get include/net/addrconf.h:313 [inline]
> > __in6_dev_get include/net/addrconf.h:311 [inline]
> > neigh_reduce drivers/net/vxlan.c:2167 [inline]
> > vxlan_xmit+0x34d5/0x4c30 drivers/net/vxlan.c:2919
> > __netdev_start_xmit include/linux/netdevice.h:4944 [inline]
> > netdev_start_xmit include/linux/netdevice.h:4958 [inline]
> > xmit_one net/core/dev.c:3654 [inline]
> > dev_hard_start_xmit+0x1eb/0x920 net/core/dev.c:3670
> > __dev_queue_xmit+0x2133/0x3130 net/core/dev.c:4246
> > ipvlan_process_multicast+0xa99/0xd70 drivers/net/ipvlan/ipvlan_core.c:287
> > process_one_work+0x98d/0x1600 kernel/workqueue.c:2276
> > worker_thread+0x64c/0x1120 kernel/workqueue.c:2422
> > kthread+0x3b1/0x4a0 kernel/kthread.c:313
> > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294
> >
> > Fixes: f564f45c4518 ("vxlan: add ipv6 proxy support")
> > Signed-off-by: Eric Dumazet <edumazet@google.com>
> > Reported-by: syzbot <syzkaller@googlegroups.com>
>
> [ +Paul/Toke ]
>
> Only a side comment on this fix given the series under [0] where we remove the
> rcu_read_lock() given covered by rcu_read_lock_bh():
>
> [...] It seems [1] that back in the early days of XDP, local_bh_disable() did
> not provide RCU protection, which is why the rcu_read_lock() calls were added
> to drivers in the first place. But according to Paul [2], in recent kernels
> a local_bh_disable()/local_bh_enable() pair functions as one big RCU
> read-side section, so no further protection is needed. This even applies to
> -rt kernels, which has an explicit rcu_read_lock() in place as part of the
> local_bh_disable() [3]. [...]
>
> Paul/Toke, with regards to related questions under [1], I presume there should
> additionally be a fixup for lockdep /in general/ to silence warning like these ?
Do these commits help?
1feb2cc8db48 ("lockdep: Explicitly flag likely false-positive report")
3066820034b5 ("rcu: Reject RCU_LOCKDEP_WARN() false positives")
With a bit of luck, these will go into the upcoming merge window.
Thanx, Paul
> [0] https://lore.kernel.org/bpf/20210617212748.32456-1-toke@redhat.com/
> [1] https://lore.kernel.org/bpf/1881ecbe-06ec-6b0a-836c-033c31fabef4@iogearbox.net/
>
> > ---
> > drivers/net/vxlan.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
> > index 02a14f1b938ad50fc28044b7670ba5f6bf924345..5a8df5a195cb5700c45b4785355ef8ed84866052 100644
> > --- a/drivers/net/vxlan.c
> > +++ b/drivers/net/vxlan.c
> > @@ -2164,6 +2164,7 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni)
> > struct neighbour *n;
> > struct nd_msg *msg;
> > + rcu_read_lock();
> > in6_dev = __in6_dev_get(dev);
> > if (!in6_dev)
> > goto out;
> > @@ -2215,6 +2216,7 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni)
> > }
> > out:
> > + rcu_read_unlock();
> > consume_skb(skb);
> > return NETDEV_TX_OK;
> > }
> >
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH net] vxlan: add missing rcu_read_lock() in neigh_reduce()
2021-06-21 14:44 [PATCH net] vxlan: add missing rcu_read_lock() in neigh_reduce() Eric Dumazet
2021-06-21 16:04 ` Daniel Borkmann
@ 2021-06-22 16:50 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 4+ messages in thread
From: patchwork-bot+netdevbpf @ 2021-06-22 16:50 UTC (permalink / raw)
To: Eric Dumazet; +Cc: davem, kuba, netdev, edumazet, syzkaller
Hello:
This patch was applied to netdev/net.git (refs/heads/master):
On Mon, 21 Jun 2021 07:44:17 -0700 you wrote:
> From: Eric Dumazet <edumazet@google.com>
>
> syzbot complained in neigh_reduce(), because rcu_read_lock_bh()
> is treated differently than rcu_read_lock()
>
> WARNING: suspicious RCU usage
> 5.13.0-rc6-syzkaller #0 Not tainted
>
> [...]
Here is the summary with links:
- [net] vxlan: add missing rcu_read_lock() in neigh_reduce()
https://git.kernel.org/netdev/net/c/85e8b032d6eb
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-06-22 16:50 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2021-06-21 14:44 [PATCH net] vxlan: add missing rcu_read_lock() in neigh_reduce() Eric Dumazet
2021-06-21 16:04 ` Daniel Borkmann
2021-06-21 18:27 ` Paul E. McKenney
2021-06-22 16:50 ` patchwork-bot+netdevbpf
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