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Message-ID: <CANn89iJiQeF=7g0wFVOZ=TMUnL-7U0xvw4ZQL5H5f4+ChBp__w@mail.gmail.com>
Date: Fri, 17 Jan 2025 05:14:04 +0100
From: Eric Dumazet <edumazet@...gle.com>
To: syzbot <syzbot+5b9196ecf74447172a9a@...kaller.appspotmail.com>
Cc: davem@...emloft.net, johannes@...solutions.net, kuba@...nel.org,
linux-kernel@...r.kernel.org, linux-wireless@...r.kernel.org,
netdev@...r.kernel.org, pabeni@...hat.com, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [wireless?] possible deadlock in ieee80211_remove_interfaces
On Fri, Jan 17, 2025 at 4:58 AM syzbot
<syzbot+5b9196ecf74447172a9a@...kaller.appspotmail.com> wrote:
>
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit: 8d20dcda404d selftests: drv-net-hw: inject pp_alloc_fail e..
> git tree: net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=14ef5a18580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=c30f048a4f12891
> dashboard link: https://syzkaller.appspot.com/bug?extid=5b9196ecf74447172a9a
> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15d7a1f8580000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/5ce07c743ced/disk-8d20dcda.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/66f2a9a35d5e/vmlinux-8d20dcda.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/4c790c086a46/bzImage-8d20dcda.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+5b9196ecf74447172a9a@...kaller.appspotmail.com
>
> ======================================================
> WARNING: possible circular locking dependency detected
> 6.13.0-rc7-syzkaller-01131-g8d20dcda404d #0 Not tainted
> ------------------------------------------------------
> kworker/u8:6/3534 is trying to acquire lock:
> ffffffff8fcb4a08 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_acquire_if_cleanup_net net/core/dev.c:10281 [inline]
> ffffffff8fcb4a08 (rtnl_mutex){+.+.}-{4:4}, at: unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11783
>
> but task is already holding lock:
> ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6034 [inline]
> ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ieee80211_remove_interfaces+0x129/0x700 net/mac80211/iface.c:2276
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #1 (&rdev->wiphy.mtx){+.+.}-{4:4}:
> lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
> __mutex_lock_common kernel/locking/mutex.c:585 [inline]
> __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
> wiphy_lock include/net/cfg80211.h:6019 [inline]
> wiphy_register+0x1a49/0x27b0 net/wireless/core.c:1006
> ieee80211_register_hw+0x30fb/0x3e10 net/mac80211/main.c:1582
> mac80211_hwsim_new_radio+0x2a9f/0x4a90 drivers/net/wireless/virtual/mac80211_hwsim.c:5558
> init_mac80211_hwsim+0x87a/0xb00 drivers/net/wireless/virtual/mac80211_hwsim.c:6910
> do_one_initcall+0x248/0x870 init/main.c:1266
> do_initcall_level+0x157/0x210 init/main.c:1328
> do_initcalls+0x3f/0x80 init/main.c:1344
> kernel_init_freeable+0x435/0x5d0 init/main.c:1577
> kernel_init+0x1d/0x2b0 init/main.c:1466
> ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>
> -> #0 (rtnl_mutex){+.+.}-{4:4}:
> check_prev_add kernel/locking/lockdep.c:3161 [inline]
> check_prevs_add kernel/locking/lockdep.c:3280 [inline]
> validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
> __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
> lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
> __mutex_lock_common kernel/locking/mutex.c:585 [inline]
> __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
> rtnl_acquire_if_cleanup_net net/core/dev.c:10281 [inline]
> unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11783
> unregister_netdevice_many net/core/dev.c:11866 [inline]
> unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11732
> unregister_netdevice include/linux/netdevice.h:3320 [inline]
> _cfg80211_unregister_wdev+0x163/0x590 net/wireless/core.c:1251
> ieee80211_remove_interfaces+0x4ef/0x700 net/mac80211/iface.c:2301
> ieee80211_unregister_hw+0x5d/0x2c0 net/mac80211/main.c:1676
> mac80211_hwsim_del_radio+0x2c4/0x4c0 drivers/net/wireless/virtual/mac80211_hwsim.c:5664
> hwsim_exit_net+0x5c1/0x670 drivers/net/wireless/virtual/mac80211_hwsim.c:6544
> ops_exit_list net/core/net_namespace.c:172 [inline]
> cleanup_net+0x812/0xd60 net/core/net_namespace.c:652
> process_one_work kernel/workqueue.c:3236 [inline]
> process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
> worker_thread+0x870/0xd30 kernel/workqueue.c:3398
> kthread+0x2f0/0x390 kernel/kthread.c:389
> ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
>
> other info that might help us debug this:
>
> Possible unsafe locking scenario:
>
> CPU0 CPU1
> ---- ----
> lock(&rdev->wiphy.mtx);
> lock(rtnl_mutex);
> lock(&rdev->wiphy.mtx);
> lock(rtnl_mutex);
>
> *** DEADLOCK ***
>
> 4 locks held by kworker/u8:6/3534:
> #0: ffff88801baf5948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline]
> #0: ffff88801baf5948 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317
> #1: ffffc9000d507d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline]
> #1: ffffc9000d507d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317
> #2: ffffffff8fca8290 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0x17a/0xd60 net/core/net_namespace.c:606
> #3: ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6034 [inline]
> #3: ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ieee80211_remove_interfaces+0x129/0x700 net/mac80211/iface.c:2276
>
> stack backtrace:
> CPU: 1 UID: 0 PID: 3534 Comm: kworker/u8:6 Not tainted 6.13.0-rc7-syzkaller-01131-g8d20dcda404d #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
> Workqueue: netns cleanup_net
> Call Trace:
> <TASK>
> __dump_stack lib/dump_stack.c:94 [inline]
> dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
> print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074
> check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206
> check_prev_add kernel/locking/lockdep.c:3161 [inline]
> check_prevs_add kernel/locking/lockdep.c:3280 [inline]
> validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904
> __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226
> lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849
> __mutex_lock_common kernel/locking/mutex.c:585 [inline]
> __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735
> rtnl_acquire_if_cleanup_net net/core/dev.c:10281 [inline]
> unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11783
> unregister_netdevice_many net/core/dev.c:11866 [inline]
> unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11732
> unregister_netdevice include/linux/netdevice.h:3320 [inline]
> _cfg80211_unregister_wdev+0x163/0x590 net/wireless/core.c:1251
> ieee80211_remove_interfaces+0x4ef/0x700 net/mac80211/iface.c:2301
> ieee80211_unregister_hw+0x5d/0x2c0 net/mac80211/main.c:1676
> mac80211_hwsim_del_radio+0x2c4/0x4c0 drivers/net/wireless/virtual/mac80211_hwsim.c:5664
> hwsim_exit_net+0x5c1/0x670 drivers/net/wireless/virtual/mac80211_hwsim.c:6544
> ops_exit_list net/core/net_namespace.c:172 [inline]
> cleanup_net+0x812/0xd60 net/core/net_namespace.c:652
> process_one_work kernel/workqueue.c:3236 [inline]
> process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317
> worker_thread+0x870/0xd30 kernel/workqueue.c:3398
> kthread+0x2f0/0x390 kernel/kthread.c:389
> ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
> ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
> </TASK>
> hsr_slave_0: left promiscuous mode
> hsr_slave_1: left promiscuous mode
> batman_adv: batadv0: Interface deactivated: batadv_slave_0
> batman_adv: batadv0: Removing interface: batadv_slave_0
> batman_adv: batadv0: Interface deactivated: batadv_slave_1
> batman_adv: batadv0: Removing interface: batadv_slave_1
> veth1_macvtap: left promiscuous mode
> veth0_macvtap: left promiscuous mode
> veth1_vlan: left promiscuous mode
> veth0_vlan: left promiscuous mode
> team0 (unregistering): Port device team_slave_1 removed
> team0 (unregistering): Port device team_slave_0 removed
> bridge0: port 2(bridge_slave_1) entered blocking state
> bridge0: port 2(bridge_slave_1) entered forwarding state
> bridge0: port 1(bridge_slave_0) entered blocking state
> bridge0: port 1(bridge_slave_0) entered forwarding state
> bridge0: port 2(bridge_slave_1) entered blocking state
> bridge0: port 2(bridge_slave_1) entered forwarding state
>
>
> ---
> If you want syzbot to run the reproducer, reply with:
> #syz test: git://repo/address.git branch-or-commit-hash
> If you attach or paste a git patch, syzbot will apply it before testing.
This repro is for another bug I think, caused by my recent commits in net-next:
83419b61d187ce22aa3da5ffdda850fca3a12600 net: reduce RTNL hold
duration in unregister_netdevice_many_notify() (part 2)
ae646f1a0bb97401bac0044bbe2a179a1e38b408 net: reduce RTNL hold
duration in unregister_netdevice_many_notify() (part 1)
cfa579f6665635b72d4a075fc91eb144c2b0f74e net: no longer hold RTNL
while calling flush_all_backlogs()
cleanup_net()
rtnl_lock();
mutex_lock(subsystem_mutex);
unregister_netdevice();
rtnl_unlock(); // LOCKDEP violation
rtnl_lock();
I will work today on a fix, auditing all unregister_netdevice() and
unregister_netdevice_many()
and select which of them can safely opt-in for a variant which _can_
temporarily release RTNL.
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