From: syzbot <syzbot+d270af829aca04e783fc@syzkaller.appspotmail.com>
To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
linux-usb@vger.kernel.org, syzkaller-bugs@googlegroups.com
Subject: [syzbot] [usb?] general protection fault in dummy_udc_start
Date: Tue, 28 Jul 2026 07:15:38 -0700 [thread overview]
Message-ID: <6a68b98a.4c659fcc.19cd90.0024.GAE@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: 62cc90241548 Merge tag 'mm-hotfixes-stable-2026-07-27-14-1..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1400788e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=145fa60d73086782
dashboard link: https://syzkaller.appspot.com/bug?extid=d270af829aca04e783fc
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1000ffde580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=164f91b9580000
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-62cc9024.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b10a9ae7e3d1/vmlinux-62cc9024.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b89124d39495/bzImage-62cc9024.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d270af829aca04e783fc@syzkaller.appspotmail.com
dummy_hcd dummy_hcd.0: remove, state 4
usb usb5: USB disconnect, device number 1
dummy_hcd dummy_hcd.0: stopped
dummy_hcd dummy_hcd.0: USB bus 5 deregistered
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 2 UID: 0 PID: 5931 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:dummy_udc_start+0x91/0x1d0 drivers/usb/gadget/udc/dummy_hcd.c:1022
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 28 01 00 00 4c 8b ab 90 06 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 10 01 00 00 83 ed 01 bf 02 00 00 00 49 8b 5d 00
RSP: 0018:ffffc90003997b48 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88802c4e0c00 RCX: ffffffff87d0c8f9
RDX: 0000000000000000 RSI: ffffffff87d0c907 RDI: ffff88802c4e1290
RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000005
R10: 0000000000000003 R11: 0000000000000000 R12: ffff88802e7c2050
R13: 0000000000000000 R14: ffff88802d49c4f1 R15: ffff88802d49c008
FS: 0000555566288500(0000) GS:ffff8880d5fdc000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f24ccd874c0 CR3: 000000003c5d9000 CR4: 0000000000352ef0
Call Trace:
<TASK>
usb_gadget_udc_start_locked drivers/usb/gadget/udc/core.c:1237 [inline]
gadget_bind_driver+0x4ac/0xbf0 drivers/usb/gadget/udc/core.c:1667
call_driver_probe drivers/base/dd.c:628 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:706
__driver_probe_device+0x20e/0x450 drivers/base/dd.c:868
driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
__driver_attach+0x21f/0x5b0 drivers/base/dd.c:1292
bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383
bus_add_driver+0x305/0x5b0 drivers/base/bus.c:763
driver_register+0x1e2/0x360 drivers/base/driver.c:174
usb_gadget_register_driver_owner+0x132/0x210 drivers/usb/gadget/udc/core.c:1752
raw_ioctl_run drivers/usb/gadget/legacy/raw_gadget.c:596 [inline]
raw_ioctl+0x1a85/0x2b80 drivers/usb/gadget/legacy/raw_gadget.c:1307
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f24ccd9db2b
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:00007ffd9eb276f0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f24ccd9db2b
RDX: 0000000000000000 RSI: 0000000000005501 RDI: 0000000000000004
RBP: 00007ffd9eb287c0 R08: 0000000000000001 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00002000000001c0 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dummy_udc_start+0x91/0x1d0 drivers/usb/gadget/udc/dummy_hcd.c:1022
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 28 01 00 00 4c 8b ab 90 06 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 ea 48 c1 ea 03 <80> 3c 02 00 0f 85 10 01 00 00 83 ed 01 bf 02 00 00 00 49 8b 5d 00
RSP: 0018:ffffc90003997b48 EFLAGS: 00010246
RAX: dffffc0000000000 RBX: ffff88802c4e0c00 RCX: ffffffff87d0c8f9
RDX: 0000000000000000 RSI: ffffffff87d0c907 RDI: ffff88802c4e1290
RBP: 0000000000000003 R08: 0000000000000005 R09: 0000000000000005
R10: 0000000000000003 R11: 0000000000000000 R12: ffff88802e7c2050
R13: 0000000000000000 R14: ffff88802d49c4f1 R15: ffff88802d49c008
FS: 0000555566288500(0000) GS:ffff8880d60dc000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f24ccfec000 CR3: 000000003c5d9000 CR4: 0000000000352ef0
----------------
Code disassembly (best guess):
0: df 48 89 fisttps -0x77(%rax)
3: fa cli
4: 48 c1 ea 03 shr $0x3,%rdx
8: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
c: 0f 85 28 01 00 00 jne 0x13a
12: 4c 8b ab 90 06 00 00 mov 0x690(%rbx),%r13
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 4c 89 ea mov %r13,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2e: 0f 85 10 01 00 00 jne 0x144
34: 83 ed 01 sub $0x1,%ebp
37: bf 02 00 00 00 mov $0x2,%edi
3c: 49 8b 5d 00 mov 0x0(%r13),%rbx
---
This report is generated by a bot. It may contain errors.
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reply other threads:[~2026-07-28 14:15 UTC|newest]
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