[v6.6] WARNING in __ieee80211_beacon_get

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syzbot

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Jun 17, 2025, 5:14:23 AM6/17/25
to syzkaller...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: c2603c511feb Linux 6.6.93
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13c455d4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=486bade17c8c30b9
dashboard link: https://syzkaller.appspot.com/bug?extid=feb2f6f6d7672169abb7
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8754f950a6e7/disk-c2603c51.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3b19332dbf63/vmlinux-c2603c51.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cb245e836038/bzImage-c2603c51.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+feb2f6...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 11074 at net/mac80211/tx.c:5019 __ieee80211_beacon_update_cntdwn net/mac80211/tx.c:5019 [inline]
WARNING: CPU: 1 PID: 11074 at net/mac80211/tx.c:5019 __ieee80211_beacon_get+0x1233/0x1600 net/mac80211/tx.c:5430
Modules linked in:
CPU: 1 PID: 11074 Comm: syz.2.1684 Not tainted 6.6.93-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__ieee80211_beacon_update_cntdwn net/mac80211/tx.c:5019 [inline]
RIP: 0010:__ieee80211_beacon_get+0x1233/0x1600 net/mac80211/tx.c:5430
Code: 24 4c 89 e7 e8 ce dd dd f7 45 31 f6 4c 8b bc 24 a0 00 00 00 e9 7a fe ff ff e8 19 57 9f f7 0f 0b e9 f6 f7 ff ff e8 0d 57 9f f7 <0f> 0b e9 48 fb ff ff e8 01 57 9f f7 48 c7 c7 e0 28 23 8e 4c 89 e6
RSP: 0018:ffffc900001f0a18 EFLAGS: 00010246
RAX: ffffffff89e63fd3 RBX: ffffffff89e62dd6 RCX: ffff888028629e00
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff888028629e00 R09: 0000000000000003
R10: 0000000000000007 R11: 0000000000000100 R12: ffff8880532163c0
R13: dffffc0000000000 R14: ffff8880532168b0 R15: ffff88805f443024
FS: 00007fe98dbbd6c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 000000002ebb0000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
ieee80211_beacon_get_tim+0xb8/0x560 net/mac80211/tx.c:5557
ieee80211_beacon_get include/net/mac80211.h:5438 [inline]
mac80211_hwsim_beacon_tx+0x3c7/0x780 drivers/net/wireless/virtual/mac80211_hwsim.c:2260
__iterate_interfaces+0x243/0x500 net/mac80211/util.c:766
ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:802
mac80211_hwsim_beacon+0xbb/0x1b0 drivers/net/wireless/virtual/mac80211_hwsim.c:2290
__run_hrtimer kernel/time/hrtimer.c:1755 [inline]
__hrtimer_run_queues+0x51e/0xc40 kernel/time/hrtimer.c:1819
hrtimer_run_softirq+0x187/0x2b0 kernel/time/hrtimer.c:1836
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:finish_task_switch+0x26a/0x920 kernel/sched/core.c:5255
Code: 0f 84 37 01 00 00 48 85 db 0f 85 56 01 00 00 e9 f6 04 00 00 4c 8b 75 d0 4c 89 e7 e8 90 6d 13 09 e8 0b b5 2f 00 fb 4c 8b 65 c0 <49> 8d bc 24 f8 15 00 00 48 89 f8 48 c1 e8 03 42 0f b6 04 28 84 c0
RSP: 0018:ffffc9000b66f658 EFLAGS: 00000282
RAX: b17239adbb9faf00 RBX: 0000000000000000 RCX: b17239adbb9faf00
RDX: dffffc0000000000 RSI: ffffffff8aaab2c0 RDI: ffffffff8afc6780
RBP: ffffc9000b66f6b0 R08: ffffffff8e49a76f R09: 1ffffffff1c934ed
R10: dffffc0000000000 R11: fffffbfff1c934ee R12: ffff888028629e00
R13: dffffc0000000000 R14: ffff88801873da00 R15: ffff8880b8f3cf08
context_switch kernel/sched/core.c:5384 [inline]
__schedule+0x14ea/0x4580 kernel/sched/core.c:6700
schedule+0xbd/0x170 kernel/sched/core.c:6774
schedule_timeout+0x160/0x280 kernel/time/timer.c:2167
snd_rawmidi_write+0x398/0xb10 sound/core/rawmidi.c:1674
do_loop_readv_writev fs/read_write.c:-1 [inline]
do_iter_write+0x50e/0xc70 fs/read_write.c:862
vfs_writev fs/read_write.c:933 [inline]
do_writev+0x252/0x410 fs/read_write.c:976
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe98cd8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe98dbbd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fe98cfb5fa0 RCX: 00007fe98cd8e929
RDX: 0000000000000002 RSI: 0000200000000840 RDI: 0000000000000009
RBP: 00007fe98ce10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fe98cfb5fa0 R15: 00007ffe20ca8368
</TASK>
----------------
Code disassembly (best guess):
0: 0f 84 37 01 00 00 je 0x13d
6: 48 85 db test %rbx,%rbx
9: 0f 85 56 01 00 00 jne 0x165
f: e9 f6 04 00 00 jmp 0x50a
14: 4c 8b 75 d0 mov -0x30(%rbp),%r14
18: 4c 89 e7 mov %r12,%rdi
1b: e8 90 6d 13 09 call 0x9136db0
20: e8 0b b5 2f 00 call 0x2fb530
25: fb sti
26: 4c 8b 65 c0 mov -0x40(%rbp),%r12
* 2a: 49 8d bc 24 f8 15 00 lea 0x15f8(%r12),%rdi <-- trapping instruction
31: 00
32: 48 89 f8 mov %rdi,%rax
35: 48 c1 e8 03 shr $0x3,%rax
39: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax
3e: 84 c0 test %al,%al


---
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syzbot

unread,
Jun 22, 2025, 7:50:27 PM6/22/25
to syzkaller...@googlegroups.com
syzbot has found a reproducer for the following issue on:

HEAD commit: 6282921b6825 Linux 6.6.94
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=11915b0c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=96da6b2210cda427
dashboard link: https://syzkaller.appspot.com/bug?extid=feb2f6f6d7672169abb7
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10d12dd4580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1618f370580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/a3bf0d8e22b2/disk-6282921b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d1d442f782d0/vmlinux-6282921b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a8378f4b7e1b/bzImage-6282921b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+feb2f6...@syzkaller.appspotmail.com

------------[ cut here ]------------
WARNING: CPU: 1 PID: 5887 at net/mac80211/tx.c:5019 __ieee80211_beacon_update_cntdwn net/mac80211/tx.c:5019 [inline]
WARNING: CPU: 1 PID: 5887 at net/mac80211/tx.c:5019 __ieee80211_beacon_get+0x1233/0x1600 net/mac80211/tx.c:5430
Modules linked in:
CPU: 1 PID: 5887 Comm: kworker/1:4H Not tainted 6.6.94-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_highpri snd_vmidi_output_work
RIP: 0010:__ieee80211_beacon_update_cntdwn net/mac80211/tx.c:5019 [inline]
RIP: 0010:__ieee80211_beacon_get+0x1233/0x1600 net/mac80211/tx.c:5430
Code: 24 4c 89 e7 e8 3e b0 dd f7 45 31 f6 4c 8b bc 24 a0 00 00 00 e9 7a fe ff ff e8 59 27 9f f7 0f 0b e9 f6 f7 ff ff e8 4d 27 9f f7 <0f> 0b e9 48 fb ff ff e8 41 27 9f f7 48 c7 c7 60 2c 23 8e 4c 89 e6
RSP: 0018:ffffc900001f0a18 EFLAGS: 00010246
RAX: ffffffff89e66e83 RBX: ffffffff89e65c86 RCX: ffff8880288dda00
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffff8880288dda00 R09: 0000000000000003
R10: 0000000000000007 R11: 0000000000000100 R12: ffff888067c023c0
R13: dffffc0000000000 R14: ffff888067c028b0 R15: ffff888067ebb424
FS: 0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000004000 CR3: 00000000757ad000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
ieee80211_beacon_get_tim+0xb8/0x560 net/mac80211/tx.c:5557
ieee80211_beacon_get include/net/mac80211.h:5438 [inline]
mac80211_hwsim_beacon_tx+0x3c7/0x780 drivers/net/wireless/virtual/mac80211_hwsim.c:2260
__iterate_interfaces+0x243/0x500 net/mac80211/util.c:766
ieee80211_iterate_active_interfaces_atomic+0xdb/0x180 net/mac80211/util.c:802
mac80211_hwsim_beacon+0xbb/0x1b0 drivers/net/wireless/virtual/mac80211_hwsim.c:2290
__run_hrtimer kernel/time/hrtimer.c:1755 [inline]
__hrtimer_run_queues+0x51e/0xc40 kernel/time/hrtimer.c:1819
hrtimer_run_softirq+0x187/0x2b0 kernel/time/hrtimer.c:1836
handle_softirqs+0x280/0x820 kernel/softirq.c:578
__do_softirq kernel/softirq.c:612 [inline]
invoke_softirq kernel/softirq.c:452 [inline]
__irq_exit_rcu+0xc7/0x190 kernel/softirq.c:661
irq_exit_rcu+0x9/0x20 kernel/softirq.c:673
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1088 [inline]
sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1088
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:687
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xa9/0x110 kernel/locking/spinlock.c:194
Code: 74 05 e8 7a 26 1c f7 48 c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f6 44 24 21 02 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 82 91 eb f6 65 8b 05 93 e7 93 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc9000493f9e0 EFLAGS: 00000206
RAX: 86706e9d33bed100 RBX: 0000000000000a06 RCX: 86706e9d33bed100
RDX: dffffc0000000000 RSI: ffffffff8aaab2c0 RDI: 0000000000000001
RBP: ffffc9000493fa68 R08: ffffffff90d85617 R09: 1ffffffff21b0ac2
R10: dffffc0000000000 R11: fffffbfff21b0ac3 R12: dffffc0000000000
R13: 0000000000000000 R14: ffff88807763c4a0 R15: 1ffff92000927f3c
spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
snd_midi_event_encode_byte+0x7de/0xcb0 sound/core/seq/seq_midi_event.c:239
snd_vmidi_output_work+0x1ec/0x410 sound/core/seq/seq_virmidi.c:153
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>
----------------
Code disassembly (best guess):
0: 74 05 je 0x7
2: e8 7a 26 1c f7 call 0xf71c2681
7: 48 c7 44 24 20 00 00 movq $0x0,0x20(%rsp)
e: 00 00
10: 9c pushf
11: 8f 44 24 20 pop 0x20(%rsp)
15: f6 44 24 21 02 testb $0x2,0x21(%rsp)
1a: 75 4b jne 0x67
1c: f7 c3 00 02 00 00 test $0x200,%ebx
22: 74 01 je 0x25
24: fb sti
25: bf 01 00 00 00 mov $0x1,%edi
* 2a: e8 82 91 eb f6 call 0xf6eb91b1 <-- trapping instruction
2f: 65 8b 05 93 e7 93 75 mov %gs:0x7593e793(%rip),%eax # 0x7593e7c9
36: 85 c0 test %eax,%eax
38: 74 3c je 0x76
3a: 48 rex.W
3b: c7 .byte 0xc7
3c: 04 24 add $0x24,%al
3e: 0e (bad)
3f: 36 ss


---
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