Re: [syzbot] [usb?] general protection fault in dummy_timer (2)

syzbot
2025-03-04T01:01:27Z

syzbot has found a reproducer for the following issue on:

HEAD commit: 811d22141369 usb: dwc3: exynos: add support for exynos7870
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
console output: https://syzkaller.appspot.com/x/log.txt?x=1690e464580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f429368eda610a89
dashboard link: https://syzkaller.appspot.com/bug?extid=faf3a6cf579fc65591ca
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11500697980000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c0764bd2a6ef/disk-811d2214.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a8d014106735/vmlinux-811d2214.xz
kernel image: https://storage.googleapis.com/syzbot-assets/80062d83482e/bzImage-811d2214.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+faf3a6cf579fc65591ca@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000060: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000300-0x0000000000000307]
CPU: 0 UID: 0 PID: 7918 Comm: syz-executor Not tainted 6.14.0-rc3-syzkaller-00056-g811d22141369 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:strcmp+0x5b/0xb0 lib/string.c:277
Code: fa 48 c1 e8 03 83 e2 07 42 0f b6 04 28 38 d0 7f 04 84 c0 75 58 0f b6 6b ff 4c 8d 66 01 48 89 f0 48 89 f2 48 c1 e8 03 83 e2 07 <42> 0f b6 04 28 38 d0 7f 04 84 c0 75 2c 41 3a 6c 24 ff 74 ae 19 c0
RSP: 0018:ffffc90000007848 EFLAGS: 00010046
RAX: 0000000000000060 RBX: ffffffff8747ce21 RCX: ffffffff8fb2a5e8
RDX: 0000000000000000 RSI: 0000000000000300 RDI: ffffffff8747ce20
RBP: 0000000000000026 R08: 0000000000000001 R09: dffffc0000000000
R10: ffffffff8fb2a5f8 R11: ffffffff8fb2a5e8 R12: 0000000000000301
R13: dffffc0000000000 R14: 00000000000003b1 R15: ffffffff934e19e0
FS: 000055558b609500(0000) GS:ffff8881f5800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f143e94aea2 CR3: 000000012b09c000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
count_matching_names kernel/locking/lockdep.c:877 [inline]
register_lock_class+0x63b/0x1240 kernel/locking/lockdep.c:1342
__lock_acquire+0x135/0x3c40 kernel/locking/lockdep.c:5103
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x3a/0x60 kernel/locking/spinlock.c:162
complete_with_flags kernel/sched/completion.c:20 [inline]
complete+0x1d/0x200 kernel/sched/completion.c:47
transfer drivers/usb/gadget/udc/dummy_hcd.c:1523 [inline]
dummy_timer+0x1c37/0x3960 drivers/usb/gadget/udc/dummy_hcd.c:1978
__run_hrtimer kernel/time/hrtimer.c:1801 [inline]
__hrtimer_run_queues+0x20a/0xae0 kernel/time/hrtimer.c:1865
hrtimer_run_softirq+0x17d/0x350 kernel/time/hrtimer.c:1882
handle_softirqs+0x206/0x8d0 kernel/softirq.c:561
__do_softirq kernel/softirq.c:595 [inline]
invoke_softirq kernel/softirq.c:435 [inline]
__irq_exit_rcu+0xfa/0x160 kernel/softirq.c:662
irq_exit_rcu+0x9/0x30 kernel/softirq.c:678
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline]
sysvec_apic_timer_interrupt+0x90/0xb0 arch/x86/kernel/apic/apic.c:1049
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire.part.0+0x155/0x380 kernel/locking/lockdep.c:5816
Code: b8 ff ff ff ff 65 0f c1 05 90 2f aa 7e 83 f8 01 0f 85 d0 01 00 00 9c 58 f6 c4 02 0f 85 e5 01 00 00 48 85 ed 0f 85 b6 01 00 00 <48> b8 00 00 00 00 00 fc ff df 48 01 c3 48 c7 03 00 00 00 00 48 c7
RSP: 0018:ffffc9000446fc98 EFLAGS: 00000206
RAX: 0000000000000046 RBX: 1ffff9200088df94 RCX: 00000000521e9cf7
RDX: 0000000000000001 RSI: ffffffff87281ac0 RDI: ffffffff8747c1a0
RBP: 0000000000000200 R08: 0000000000000000 R09: fffffbfff1f5cdc0
R10: ffffffff8fae6e07 R11: 0000000000000000 R12: 0000000000000000
R13: ffffffff88ebe3c0 R14: 0000000000000000 R15: 0000000000000000
rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
rcu_read_lock_sched include/linux/rcupdate.h:941 [inline]
fd_install+0xc0/0x750 fs/file.c:639
do_sys_openat2+0x1a4/0x1e0 fs/open.c:1433
do_sys_open fs/open.c:1443 [inline]
__do_sys_openat fs/open.c:1459 [inline]
__se_sys_openat fs/open.c:1454 [inline]
__x64_sys_openat+0x175/0x210 fs/open.c:1454
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: 0033:0x7f143e88ba51
Code: 75 57 89 f0 25 00 00 41 00 3d 00 00 41 00 74 49 80 3d fa 1a 1f 00 00 74 6d 89 da 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 93 00 00 00 48 8b 54 24 28 64 48 2b 14 25
RSP: 002b:00007ffc6205c990 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000000000080001 RCX: 00007f143e88ba51
RDX: 0000000000080001 RSI: 00007f143e90fadc RDI: 00000000ffffff9c
RBP: 00007f143e90fadc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000004
R13: 00007ffc6205ca30 R14: 00000000000aeedc R15: 00007ffc6205cfa0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:strcmp+0x5b/0xb0 lib/string.c:277
Code: fa 48 c1 e8 03 83 e2 07 42 0f b6 04 28 38 d0 7f 04 84 c0 75 58 0f b6 6b ff 4c 8d 66 01 48 89 f0 48 89 f2 48 c1 e8 03 83 e2 07 <42> 0f b6 04 28 38 d0 7f 04 84 c0 75 2c 41 3a 6c 24 ff 74 ae 19 c0
RSP: 0018:ffffc90000007848 EFLAGS: 00010046
RAX: 0000000000000060 RBX: ffffffff8747ce21 RCX: ffffffff8fb2a5e8
RDX: 0000000000000000 RSI: 0000000000000300 RDI: ffffffff8747ce20
RBP: 0000000000000026 R08: 0000000000000001 R09: dffffc0000000000
R10: ffffffff8fb2a5f8 R11: ffffffff8fb2a5e8 R12: 0000000000000301
R13: dffffc0000000000 R14: 00000000000003b1 R15: ffffffff934e19e0
FS: 000055558b609500(0000) GS:ffff8881f5800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f143e94aea2 CR3: 000000012b09c000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: fa cli
1: 48 c1 e8 03 shr $0x3,%rax
5: 83 e2 07 and $0x7,%edx
8: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax
d: 38 d0 cmp %dl,%al
f: 7f 04 jg 0x15
11: 84 c0 test %al,%al
13: 75 58 jne 0x6d
15: 0f b6 6b ff movzbl -0x1(%rbx),%ebp
19: 4c 8d 66 01 lea 0x1(%rsi),%r12
1d: 48 89 f0 mov %rsi,%rax
20: 48 89 f2 mov %rsi,%rdx
23: 48 c1 e8 03 shr $0x3,%rax
27: 83 e2 07 and $0x7,%edx
* 2a: 42 0f b6 04 28 movzbl (%rax,%r13,1),%eax <-- trapping instruction
2f: 38 d0 cmp %dl,%al
31: 7f 04 jg 0x37
33: 84 c0 test %al,%al
35: 75 2c jne 0x63
37: 41 3a 6c 24 ff cmp -0x1(%r12),%bpl
3c: 74 ae je 0xffffffec
3e: 19 c0 sbb %eax,%eax

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