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Message-Id: <20240730152210.25153-1-aha310510@gmail.com>
Date: Wed, 31 Jul 2024 00:22:10 +0900
From: Jeongjun Park <aha310510@...il.com>
To: davem@...emloft.net,
edumazet@...gle.com,
kuba@...nel.org,
pabeni@...hat.com
Cc: idosch@...dia.com,
jiri@...nulli.us,
amcohen@...dia.com,
liuhangbin@...il.com,
netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
syzbot+b668da2bc4cb9670bf58@...kaller.appspotmail.com,
Jeongjun Park <aha310510@...il.com>
Subject: [PATCH net] rtnetlink: fix possible deadlock in team_port_change_check
do_setlink() changes the flag of the device and then enslaves it. However,
in this case, if the IFF_UP flag is set, the enslavement process calls
team_add_slave() to acquire 'team->lock', but when dev_open() opens the
newly enslaved device, the NETDEV_UP event occurs, and as a result,
a deadlock occurs when team_port_change_check() tries to acquire
'team->lock' again.
To solve this, you need to enslave it before changing the flag of the
device.
============================================
WARNING: possible recursive locking detected
6.10.0-syzkaller-12562-g1722389b0d86 #0 Not tainted
--------------------------------------------
syz-executor122/5360 is trying to acquire lock:
ffff88802c258d40 (team->team_lock_key){+.+.}-{3:3}, at: team_port_change_check drivers/net/team/team_core.c:2950 [inline]
ffff88802c258d40 (team->team_lock_key){+.+.}-{3:3}, at: team_device_event+0x2c7/0x770 drivers/net/team/team_core.c:2973
but task is already holding lock:
ffff88802c258d40 (team->team_lock_key){+.+.}-{3:3}, at: team_add_slave+0x9c/0x20e0 drivers/net/team/team_core.c:1975
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(team->team_lock_key);
lock(team->team_lock_key);
*** DEADLOCK ***
May be due to missing lock nesting notation
2 locks held by syz-executor122/5360:
#0: ffffffff8fa1e9a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:79 [inline]
#0: ffffffff8fa1e9a8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x372/0xea0 net/core/rtnetlink.c:6644
#1: ffff88802c258d40 (team->team_lock_key){+.+.}-{3:3}, at: team_add_slave+0x9c/0x20e0 drivers/net/team/team_core.c:1975
stack backtrace:
CPU: 0 UID: 0 PID: 5360 Comm: syz-executor122 Not tainted 6.10.0-syzkaller-12562-g1722389b0d86 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:93 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119
check_deadlock kernel/locking/lockdep.c:3061 [inline]
validate_chain kernel/locking/lockdep.c:3855 [inline]
__lock_acquire+0x2167/0x3cb0 kernel/locking/lockdep.c:5142
lock_acquire kernel/locking/lockdep.c:5759 [inline]
lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5724
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
team_port_change_check drivers/net/team/team_core.c:2950 [inline]
team_device_event+0x2c7/0x770 drivers/net/team/team_core.c:2973
notifier_call_chain+0xb9/0x410 kernel/notifier.c:93
call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:1994
call_netdevice_notifiers_extack net/core/dev.c:2032 [inline]
call_netdevice_notifiers net/core/dev.c:2046 [inline]
__dev_notify_flags+0x12d/0x2e0 net/core/dev.c:8876
dev_change_flags+0x10c/0x160 net/core/dev.c:8914
vlan_device_event+0xdfc/0x2120 net/8021q/vlan.c:468
notifier_call_chain+0xb9/0x410 kernel/notifier.c:93
call_netdevice_notifiers_info+0xbe/0x140 net/core/dev.c:1994
call_netdevice_notifiers_extack net/core/dev.c:2032 [inline]
call_netdevice_notifiers net/core/dev.c:2046 [inline]
dev_open net/core/dev.c:1515 [inline]
dev_open+0x144/0x160 net/core/dev.c:1503
team_port_add drivers/net/team/team_core.c:1216 [inline]
team_add_slave+0xacd/0x20e0 drivers/net/team/team_core.c:1976
do_set_master+0x1bc/0x230 net/core/rtnetlink.c:2701
do_setlink+0xcaf/0x3ff0 net/core/rtnetlink.c:2907
__rtnl_newlink+0xc35/0x1960 net/core/rtnetlink.c:3696
rtnl_newlink+0x67/0xa0 net/core/rtnetlink.c:3743
rtnetlink_rcv_msg+0x3c7/0xea0 net/core/rtnetlink.c:6647
netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2550
netlink_unicast_kernel net/netlink/af_netlink.c:1331 [inline]
netlink_unicast+0x544/0x830 net/netlink/af_netlink.c:1357
netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1901
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg net/socket.c:745 [inline]
____sys_sendmsg+0xab5/0xc90 net/socket.c:2597
___sys_sendmsg+0x135/0x1e0 net/socket.c:2651
__sys_sendmsg+0x117/0x1f0 net/socket.c:2680
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f424ca7e7b9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 1a 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd8c496978 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f424ca7e7b9
RDX: 0000000000000000 RSI: 0000000020000600 RDI: 0000000000000012
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007ffd8c4969a0
Reported-by: syzbot+b668da2bc4cb9670bf58@...kaller.appspotmail.com
Fixes: ec4ffd100ffb ("Revert "net: rtnetlink: Enslave device before bringing it up"")
Signed-off-by: Jeongjun Park <aha310510@...il.com>
---
net/core/rtnetlink.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 87e67194f240..178f5b85fd87 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -2896,13 +2896,6 @@ static int do_setlink(const struct sk_buff *skb,
call_netdevice_notifiers(NETDEV_CHANGEADDR, dev);
}
- if (ifm->ifi_flags || ifm->ifi_change) {
- err = dev_change_flags(dev, rtnl_dev_combine_flags(dev, ifm),
- extack);
- if (err < 0)
- goto errout;
- }
-
if (tb[IFLA_MASTER]) {
err = do_set_master(dev, nla_get_u32(tb[IFLA_MASTER]), extack);
if (err)
@@ -2910,6 +2903,13 @@ static int do_setlink(const struct sk_buff *skb,
status |= DO_SETLINK_MODIFIED;
}
+ if (ifm->ifi_flags || ifm->ifi_change) {
+ err = dev_change_flags(dev, rtnl_dev_combine_flags(dev, ifm),
+ extack);
+ if (err < 0)
+ goto errout;
+ }
+
if (tb[IFLA_CARRIER]) {
err = dev_change_carrier(dev, nla_get_u8(tb[IFLA_CARRIER]));
if (err)
--
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