123e495ecc
Apparently a concurrent linkwatch_add_event() could run while we are in __linkwatch_run_queue(). We need to free dev->linkwatch_dev_tracker tracker under lweventlist_lock protection to avoid this race. syzbot report: [ 77.935949][ T3661] reference already released. [ 77.941015][ T3661] allocated in: [ 77.944482][ T3661] linkwatch_fire_event+0x202/0x260 [ 77.950318][ T3661] netif_carrier_on+0x9c/0x100 [ 77.955120][ T3661] __ieee80211_sta_join_ibss+0xc52/0x1590 [ 77.960888][ T3661] ieee80211_sta_create_ibss.cold+0xd2/0x11f [ 77.966908][ T3661] ieee80211_ibss_work.cold+0x30e/0x60f [ 77.972483][ T3661] ieee80211_iface_work+0xb70/0xd00 [ 77.977715][ T3661] process_one_work+0x9ac/0x1680 [ 77.982671][ T3661] worker_thread+0x652/0x11c0 [ 77.987371][ T3661] kthread+0x405/0x4f0 [ 77.991465][ T3661] ret_from_fork+0x1f/0x30 [ 77.995895][ T3661] freed in: [ 77.999006][ T3661] linkwatch_do_dev+0x96/0x160 [ 78.004014][ T3661] __linkwatch_run_queue+0x233/0x6a0 [ 78.009496][ T3661] linkwatch_event+0x4a/0x60 [ 78.014099][ T3661] process_one_work+0x9ac/0x1680 [ 78.019034][ T3661] worker_thread+0x652/0x11c0 [ 78.023719][ T3661] kthread+0x405/0x4f0 [ 78.027810][ T3661] ret_from_fork+0x1f/0x30 [ 78.042541][ T3661] ------------[ cut here ]------------ [ 78.048253][ T3661] WARNING: CPU: 0 PID: 3661 at lib/ref_tracker.c:120 ref_tracker_free.cold+0x110/0x14e [ 78.062364][ T3661] Modules linked in: [ 78.066424][ T3661] CPU: 0 PID: 3661 Comm: kworker/0:5 Not tainted 5.16.0-rc4-next-20211210-syzkaller #0 [ 78.076075][ T3661] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 78.090648][ T3661] Workqueue: events linkwatch_event [ 78.095890][ T3661] RIP: 0010:ref_tracker_free.cold+0x110/0x14e [ 78.102191][ T3661] Code: ea 03 48 c1 e0 2a 0f b6 04 02 84 c0 74 04 3c 03 7e 4c 8b 7b 18 e8 6b 54 e9 fa e8 26 4d 57 f8 4c 89 ee 48 89 ef e8 fb 33 36 00 <0f> 0b 41 bd ea ff ff ff e9 bd 60 e9 fa 4c 89 f7 e8 16 45 a2 f8 e9 [ 78.127211][ T3661] RSP: 0018:ffffc90002b5fb18 EFLAGS: 00010246 [ 78.133684][ T3661] RAX: 0000000000000000 RBX: ffff88807467f700 RCX: 0000000000000000 [ 78.141928][ T3661] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000001 [ 78.150087][ T3661] RBP: ffff888057e105b8 R08: 0000000000000001 R09: ffffffff8ffa1967 [ 78.158211][ T3661] R10: 0000000000000001 R11: 0000000000000000 R12: 1ffff9200056bf65 [ 78.166204][ T3661] R13: 0000000000000292 R14: ffff88807467f718 R15: 00000000c0e0008c [ 78.174321][ T3661] FS: 0000000000000000(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 [ 78.183310][ T3661] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 78.190156][ T3661] CR2: 000000c000208800 CR3: 000000007f7b5000 CR4: 00000000003506f0 [ 78.198235][ T3661] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 78.206214][ T3661] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 78.214328][ T3661] Call Trace: [ 78.217679][ T3661] <TASK> [ 78.220621][ T3661] ? __sanitizer_cov_trace_const_cmp4+0x1c/0x70 [ 78.226981][ T3661] ? nlmsg_notify+0xbe/0x280 [ 78.231607][ T3661] ? ref_tracker_dir_exit+0x330/0x330 [ 78.237654][ T3661] ? linkwatch_do_dev+0x96/0x160 [ 78.242628][ T3661] ? __linkwatch_run_queue+0x233/0x6a0 [ 78.248170][ T3661] ? linkwatch_event+0x4a/0x60 [ 78.252946][ T3661] ? process_one_work+0x9ac/0x1680 [ 78.258136][ T3661] ? worker_thread+0x853/0x11c0 [ 78.263020][ T3661] ? kthread+0x405/0x4f0 [ 78.267905][ T3661] ? ret_from_fork+0x1f/0x30 [ 78.272670][ T3661] ? netdev_state_change+0xa1/0x130 [ 78.278019][ T3661] ? netdev_exit+0xd0/0xd0 [ 78.282466][ T3661] ? dev_activate+0x420/0xa60 [ 78.287261][ T3661] linkwatch_do_dev+0x96/0x160 [ 78.292043][ T3661] __linkwatch_run_queue+0x233/0x6a0 [ 78.297505][ T3661] ? linkwatch_do_dev+0x160/0x160 [ 78.302561][ T3661] linkwatch_event+0x4a/0x60 [ 78.307225][ T3661] process_one_work+0x9ac/0x1680 [ 78.312292][ T3661] ? pwq_dec_nr_in_flight+0x2a0/0x2a0 [ 78.317757][ T3661] ? rwlock_bug.part.0+0x90/0x90 [ 78.322726][ T3661] ? _raw_spin_lock_irq+0x41/0x50 [ 78.327844][ T3661] worker_thread+0x853/0x11c0 [ 78.332543][ T3661] ? process_one_work+0x1680/0x1680 [ 78.338500][ T3661] kthread+0x405/0x4f0 [ 78.342610][ T3661] ? set_kthread_struct+0x130/0x130 Fixes: 63f13937cbe9 ("net: linkwatch: add net device refcount tracker") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Link: https://lore.kernel.org/r/20211214051955.3569843-1-eric.dumazet@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.