[Android 5.10] general protection fault in dummy_udc_start

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 50b3a256e550 Merge 5.10.260 into android13-5.10-lts
git tree: android13-5.10-lts
console output: https://syzkaller.appspot.com/x/log.txt?x=1229f8c6580000
kernel config: https://syzkaller.appspot.com/x/.config?x=57bdfa4a173e5087
dashboard link: https://syzkaller.appspot.com/bug?extid=eeb1871d04483fca386f
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=122ce401580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=150109b9580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/34994db436ce/disk-50b3a256.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7855257a6b73/vmlinux-50b3a256.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6367ad2e120a/bzImage-50b3a256.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+eeb187...@syzkaller.appspotmail.com

usb usb1: USB disconnect, device number 1
dummy_hcd dummy_hcd.0: stopped
dummy_hcd dummy_hcd.0: USB bus 1 deregistered
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 393 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:dummy_udc_start+0xbb/0x210 drivers/usb/gadget/udc/dummy_hcd.c:989
Code: 00 00 ff 24 c5 00 2d 58 85 e8 91 eb 57 fe eb 13 e8 8a eb 57 fe eb 0c e8 83 eb 57 fe eb 05 e8 7c eb 57 fe 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 86 60 92 fe 4d 8b 36 4c 89 f7 e8
RSP: 0018:ffffc90001677ae8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888112e76010 RCX: ffff888126a14f00
RDX: 0000000000000000 RSI: ffffffff86917d60 RDI: 0000000000000003
RBP: ffffc90001677b10 R08: ffff888126a14f00 R09: 0000000000000004
R10: 0000000000000005 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000003
FS: 00007f6a994cc6c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6a99654000 CR3: 0000000112cf1000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
usb_gadget_udc_start_locked drivers/usb/gadget/udc/core.c:1169 [inline]
udc_bind_to_driver+0x333/0x6d0 drivers/usb/gadget/udc/core.c:1577
usb_gadget_probe_driver+0x1fc/0x380 drivers/usb/gadget/udc/core.c:1639
raw_ioctl_run drivers/usb/gadget/legacy/raw_gadget.c:548 [inline]
raw_ioctl+0x114d/0x3040 drivers/usb/gadget/legacy/raw_gadget.c:1255
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:753 [inline]
__se_sys_ioctl+0x121/0x1a0 fs/ioctl.c:739
__x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f6a9966ab2b
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007f6a994c9f00 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f6a9966ab2b
RDX: 0000000000000000 RSI: 0000000000005501 RDI: 0000000000000004
RBP: 00007f6a994cafd0 R08: 0000000000000001 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00002000000000c0 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
---[ end trace 64e6f843cd08a0e8 ]---
RIP: 0010:dummy_udc_start+0xbb/0x210 drivers/usb/gadget/udc/dummy_hcd.c:989
Code: 00 00 ff 24 c5 00 2d 58 85 e8 91 eb 57 fe eb 13 e8 8a eb 57 fe eb 0c e8 83 eb 57 fe eb 05 e8 7c eb 57 fe 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 86 60 92 fe 4d 8b 36 4c 89 f7 e8
RSP: 0018:ffffc90001677ae8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888112e76010 RCX: ffff888126a14f00
RDX: 0000000000000000 RSI: ffffffff86917d60 RDI: 0000000000000003
RBP: ffffc90001677b10 R08: ffff888126a14f00 R09: 0000000000000004
R10: 0000000000000005 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000003
FS: 00007f6a994cc6c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7a8f863fd0 CR3: 0000000112cf1000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 00 00 add %al,(%rax)
2: ff 24 c5 00 2d 58 85 jmp *-0x7aa7d300(,%rax,8)
9: e8 91 eb 57 fe call 0xfe57eb9f
e: eb 13 jmp 0x23
10: e8 8a eb 57 fe call 0xfe57eb9f
15: eb 0c jmp 0x23
17: e8 83 eb 57 fe call 0xfe57eb9f
1c: eb 05 jmp 0x23
1e: e8 7c eb 57 fe call 0xfe57eb9f
23: 4c 89 f0 mov %r14,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 f7 mov %r14,%rdi
34: e8 86 60 92 fe call 0xfe9260bf
39: 4d 8b 36 mov (%r14),%r14
3c: 4c 89 f7 mov %r14,%rdi
3f: e8 .byte 0xe8


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