* [PATCH v3 net-next] phonet: do not call synchronize_rcu() from phonet_route_del()
@ 2024-11-06 13:18 Eric Dumazet
2024-11-06 15:07 ` Jiri Pirko
2024-11-08 4:50 ` patchwork-bot+netdevbpf
0 siblings, 2 replies; 3+ messages in thread
From: Eric Dumazet @ 2024-11-06 13:18 UTC (permalink / raw)
To: David S . Miller, Jakub Kicinski, Paolo Abeni
Cc: netdev, eric.dumazet, Eric Dumazet, syzbot, Kuniyuki Iwashima,
Remi Denis-Courmont
Calling synchronize_rcu() while holding rcu_read_lock() is not
permitted [1]
Move the synchronize_rcu() + dev_put() to route_doit().
Alternative would be to not use rcu_read_lock() in route_doit().
[1]
WARNING: suspicious RCU usage
6.12.0-rc5-syzkaller-01056-gf07a6e6ceb05 #0 Not tainted
-----------------------------
kernel/rcu/tree.c:4092 Illegal synchronize_rcu() in RCU read-side critical section!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz-executor427/5840:
#0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
#0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: route_doit+0x3d6/0x640 net/phonet/pn_netlink.c:264
stack backtrace:
CPU: 1 UID: 0 PID: 5840 Comm: syz-executor427 Not tainted 6.12.0-rc5-syzkaller-01056-gf07a6e6ceb05 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
lockdep_rcu_suspicious+0x226/0x340 kernel/locking/lockdep.c:6821
synchronize_rcu+0xea/0x360 kernel/rcu/tree.c:4089
phonet_route_del+0xc6/0x140 net/phonet/pn_dev.c:409
route_doit+0x514/0x640 net/phonet/pn_netlink.c:275
rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6790
netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2551
netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1357
netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1901
sock_sendmsg_nosec net/socket.c:729 [inline]
__sock_sendmsg+0x221/0x270 net/socket.c:744
sock_write_iter+0x2d7/0x3f0 net/socket.c:1165
new_sync_write fs/read_write.c:590 [inline]
vfs_write+0xaeb/0xd30 fs/read_write.c:683
ksys_write+0x183/0x2b0 fs/read_write.c:736
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Fixes: 17a1ac0018ae ("phonet: Don't hold RTNL for route_doit().")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Cc: Remi Denis-Courmont <courmisch@gmail.com>
---
v3: proper tree (net-next)
v2: also move dev_put() to keep it after synchronize_rcu()
net/phonet/pn_dev.c | 5 +++--
net/phonet/pn_netlink.c | 12 ++++++++++--
2 files changed, 13 insertions(+), 4 deletions(-)
diff --git a/net/phonet/pn_dev.c b/net/phonet/pn_dev.c
index 19234d664c4fb537eba0267266efbb226cf103c3..5c36bae37b8fa85d2e97bf11d099c6c8599dcc5f 100644
--- a/net/phonet/pn_dev.c
+++ b/net/phonet/pn_dev.c
@@ -406,8 +406,9 @@ int phonet_route_del(struct net_device *dev, u8 daddr)
if (!dev)
return -ENOENT;
- synchronize_rcu();
- dev_put(dev);
+
+ /* Note : our caller must call synchronize_rcu() and dev_put(dev) */
+
return 0;
}
diff --git a/net/phonet/pn_netlink.c b/net/phonet/pn_netlink.c
index ca1f04e4a2d9eb3b2a6d6cc5b299aee28d569b08..b9043c92dc246f8c5c313b262eb3ec4afad47ecb 100644
--- a/net/phonet/pn_netlink.c
+++ b/net/phonet/pn_netlink.c
@@ -233,6 +233,7 @@ static int route_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
{
struct net *net = sock_net(skb->sk);
struct nlattr *tb[RTA_MAX+1];
+ bool sync_needed = false;
struct net_device *dev;
struct rtmsg *rtm;
u32 ifindex;
@@ -269,13 +270,20 @@ static int route_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
return -ENODEV;
}
- if (nlh->nlmsg_type == RTM_NEWROUTE)
+ if (nlh->nlmsg_type == RTM_NEWROUTE) {
err = phonet_route_add(dev, dst);
- else
+ } else {
err = phonet_route_del(dev, dst);
+ if (!err)
+ sync_needed = true;
+ }
rcu_read_unlock();
+ if (sync_needed) {
+ synchronize_rcu();
+ dev_put(dev);
+ }
if (!err)
rtm_phonet_notify(net, nlh->nlmsg_type, ifindex, dst);
--
2.47.0.199.ga7371fff76-goog
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3 net-next] phonet: do not call synchronize_rcu() from phonet_route_del()
2024-11-06 13:18 [PATCH v3 net-next] phonet: do not call synchronize_rcu() from phonet_route_del() Eric Dumazet
@ 2024-11-06 15:07 ` Jiri Pirko
2024-11-08 4:50 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Jiri Pirko @ 2024-11-06 15:07 UTC (permalink / raw)
To: Eric Dumazet
Cc: David S . Miller, Jakub Kicinski, Paolo Abeni, netdev,
eric.dumazet, syzbot, Kuniyuki Iwashima, Remi Denis-Courmont
Wed, Nov 06, 2024 at 02:18:17PM CET, edumazet@google.com wrote:
>Calling synchronize_rcu() while holding rcu_read_lock() is not
>permitted [1]
>
>Move the synchronize_rcu() + dev_put() to route_doit().
>
>Alternative would be to not use rcu_read_lock() in route_doit().
>
>[1]
>WARNING: suspicious RCU usage
>6.12.0-rc5-syzkaller-01056-gf07a6e6ceb05 #0 Not tainted
>-----------------------------
>kernel/rcu/tree.c:4092 Illegal synchronize_rcu() in RCU read-side critical section!
>
>other info that might help us debug this:
>
>rcu_scheduler_active = 2, debug_locks = 1
>1 lock held by syz-executor427/5840:
> #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
> #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
> #0: ffffffff8e937da0 (rcu_read_lock){....}-{1:2}, at: route_doit+0x3d6/0x640 net/phonet/pn_netlink.c:264
>
>stack backtrace:
>CPU: 1 UID: 0 PID: 5840 Comm: syz-executor427 Not tainted 6.12.0-rc5-syzkaller-01056-gf07a6e6ceb05 #0
>Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
>Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:94 [inline]
> dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
> lockdep_rcu_suspicious+0x226/0x340 kernel/locking/lockdep.c:6821
> synchronize_rcu+0xea/0x360 kernel/rcu/tree.c:4089
> phonet_route_del+0xc6/0x140 net/phonet/pn_dev.c:409
> route_doit+0x514/0x640 net/phonet/pn_netlink.c:275
> rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6790
> netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2551
> netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
> netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1357
> netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1901
> sock_sendmsg_nosec net/socket.c:729 [inline]
> __sock_sendmsg+0x221/0x270 net/socket.c:744
> sock_write_iter+0x2d7/0x3f0 net/socket.c:1165
> new_sync_write fs/read_write.c:590 [inline]
> vfs_write+0xaeb/0xd30 fs/read_write.c:683
> ksys_write+0x183/0x2b0 fs/read_write.c:736
> do_syscall_x64 arch/x86/entry/common.c:52 [inline]
> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
> entry_SYSCALL_64_after_hwframe+0x77/0x7f
>
>Fixes: 17a1ac0018ae ("phonet: Don't hold RTNL for route_doit().")
>Reported-by: syzbot <syzkaller@googlegroups.com>
>Signed-off-by: Eric Dumazet <edumazet@google.com>
>Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3 net-next] phonet: do not call synchronize_rcu() from phonet_route_del()
2024-11-06 13:18 [PATCH v3 net-next] phonet: do not call synchronize_rcu() from phonet_route_del() Eric Dumazet
2024-11-06 15:07 ` Jiri Pirko
@ 2024-11-08 4:50 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2024-11-08 4:50 UTC (permalink / raw)
To: Eric Dumazet
Cc: davem, kuba, pabeni, netdev, eric.dumazet, syzkaller, kuniyu,
courmisch
Hello:
This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:
On Wed, 6 Nov 2024 13:18:17 +0000 you wrote:
> Calling synchronize_rcu() while holding rcu_read_lock() is not
> permitted [1]
>
> Move the synchronize_rcu() + dev_put() to route_doit().
>
> Alternative would be to not use rcu_read_lock() in route_doit().
>
> [...]
Here is the summary with links:
- [v3,net-next] phonet: do not call synchronize_rcu() from phonet_route_del()
https://git.kernel.org/netdev/net-next/c/38a1f50a5efb
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] 3+ messages in thread
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2024-11-06 13:18 [PATCH v3 net-next] phonet: do not call synchronize_rcu() from phonet_route_del() Eric Dumazet
2024-11-06 15:07 ` Jiri Pirko
2024-11-08 4:50 ` patchwork-bot+netdevbpf
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