syzbot
WARNING in usb_ep_enable
Status:
upstream: reported C repro on 2026/07/31 20:18
Bug presence:
origin:upstream
[Documentation on labels]
Reported-by: syzbot+5bd412baa2c4211bdc7a@syzkaller.appspotmail.com
First crash: 5d05h, last: 4d00h
Sample crash report:
------------[ cut here ]------------
usb_ep_enable: ep129 (ep1in-bulk) has maxpacket 0
WARNING: CPU: 0 PID: 0 at drivers/usb/gadget/udc/core.c:108 usb_ep_enable+0x25f/0x440 drivers/usb/gadget/udc/core.c:107
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:usb_ep_enable+0x25f/0x440 drivers/usb/gadget/udc/core.c:107
Code: 49 8b 0e 48 c7 c0 80 27 d5 8a 49 c7 c0 a0 27 d5 8a 4c 0f 44 c0 48 c7 c7 40 27 d5 8a 48 c7 c6 1d 96 e1 8b 89 ea e8 c1 94 7f 03 <0f> 0b e9 e1 fe ff ff e8 95 67 43 fb 49 bc 00 00 00 00 00 fc ff df
RSP: 0018:ffffc900000076a8 EFLAGS: 00010046
RAX: bcba74ca5ada9800 RBX: ffff8881486f00e0 RCX: ffffffff8c0bc480
RDX: 0000000000000100 RSI: 0000000000000103 RDI: 0000000000000000
RBP: 0000000000000081 R08: ffff8880b902795b R09: 1ffff11017204f2b
R10: dffffc0000000000 R11: ffffed1017204f2c R12: dffffc0000000000
R13: ffff8881486f010d R14: ffff8881486f00e8 R15: ffff88802a38bb3a
FS: 0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffda3284e54 CR3: 0000000029c63000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
hidg_set_alt+0x126/0xa00 drivers/usb/gadget/function/f_hid.c:822
set_config+0x734/0xfa0 drivers/usb/gadget/composite.c:972
composite_setup+0x1999/0x2b60 drivers/usb/gadget/composite.c:1878
configfs_composite_setup+0xc3/0x100 drivers/usb/gadget/configfs.c:1492
dummy_timer+0x1338/0x33c0 drivers/usb/gadget/udc/dummy_hcd.c:1930
call_timer_fn+0x17b/0x540 kernel/time/timer.c:1648
expire_timers kernel/time/timer.c:1699 [inline]
__run_timers+0x56c/0x810 kernel/time/timer.c:1970
run_timer_softirq+0x63/0xf0 kernel/time/timer.c:1983
handle_softirqs+0x336/0x830 kernel/softirq.c:576
__do_softirq kernel/softirq.c:610 [inline]
invoke_softirq kernel/softirq.c:450 [inline]
__irq_exit_rcu+0x13b/0x230 kernel/softirq.c:659
irq_exit_rcu+0x5/0x20 kernel/softirq.c:671
instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1108 [inline]
sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1108
</IRQ>
<TASK>
asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:676
RIP: 0010:default_idle+0xb/0x10 arch/x86/kernel/process.c:730
Code: b7 48 89 df e8 36 b7 f4 f7 eb ad e8 df ab f6 ff 00 00 cc cc 00 00 cc cc 00 00 cc cc 00 00 cc 66 90 0f 00 2d e7 65 5c 00 fb f4 <c3> 0f 1f 40 00 41 57 41 56 53 49 be 00 00 00 00 00 fc ff df 65 48
RSP: 0018:ffffffff8c007dc8 EFLAGS: 000002c6
RAX: bcba74ca5ada9800 RBX: ffffffff8c0bc480 RCX: bcba74ca5ada9800
RDX: 0000000000000001 RSI: ffffffff8a2b2be0 RDI: ffffffff8a7a4200
RBP: ffffffff8c007ef8 R08: ffff8880b903b30b R09: 1ffff11017207661
R10: dffffc0000000000 R11: ffffed1017207662 R12: 1ffffffff1800fc4
R13: dffffc0000000000 R14: 1ffffffff1817890 R15: 0000000000000000
default_idle_call+0x81/0xc0 kernel/sched/idle.c:112
cpuidle_idle_call kernel/sched/idle.c:202 [inline]
do_idle+0x3a1/0x650 kernel/sched/idle.c:326
cpu_startup_entry+0x14/0x20 kernel/sched/idle.c:424
start_kernel+0x489/0x540 init/main.c:1153
secondary_startup_64_no_verify+0xb1/0xbb
</TASK>
----------------
Code disassembly (best guess):
0: b7 48 mov $0x48,%bh
2: 89 df mov %ebx,%edi
4: e8 36 b7 f4 f7 call 0xf7f4b73f
9: eb ad jmp 0xffffffb8
b: e8 df ab f6 ff call 0xfff6abef
10: 00 00 add %al,(%rax)
12: cc int3
13: cc int3
14: 00 00 add %al,(%rax)
16: cc int3
17: cc int3
18: 00 00 add %al,(%rax)
1a: cc int3
1b: cc int3
1c: 00 00 add %al,(%rax)
1e: cc int3
1f: 66 90 xchg %ax,%ax
21: 0f 00 2d e7 65 5c 00 verw 0x5c65e7(%rip) # 0x5c660f
28: fb sti
29: f4 hlt
* 2a: c3 ret <-- trapping instruction
2b: 0f 1f 40 00 nopl 0x0(%rax)
2f: 41 57 push %r15
31: 41 56 push %r14
33: 53 push %rbx
34: 49 be 00 00 00 00 00 movabs $0xdffffc0000000000,%r14
3b: fc ff df
3e: 65 gs
3f: 48 rex.W
Struck through repros no longer work on HEAD.