WARNING in dummy_free_request

Status: upstream: reported C repro on 2026/07/31 20:31
Reported-by: syzbot+742133560ef71aede3d7@syzkaller.appspotmail.com
First crash: 2d16h, last: 1d01h
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in dummy_free_request usb -1 1 2361d 2354d 0/29 closed as invalid on 2020/02/24 16:14
upstream WARNING in dummy_free_request (2) prio:normal usb -1 syz, C 6 18h22m 5d12h 0/29 upstream: reported C repro on 2026/07/29 00:10

Sample crash report:
gadgetfs: suspended from state 3
gadgetfs: disconnected
------------[ cut here ]------------
WARNING: CPU: 1 PID: 4446 at drivers/usb/gadget/udc/dummy_hcd.c:690 dummy_free_request+0x63/0x70 drivers/usb/gadget/udc/dummy_hcd.c:690
Modules linked in:
CPU: 1 PID: 4446 Comm: syz.0.22 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:dummy_free_request+0x63/0x70 drivers/usb/gadget/udc/dummy_hcd.c:690
Code: 53 fb 48 8b 03 48 39 d8 75 1b e8 58 5a 02 fb 48 89 df 5b 41 5e e9 dd fe 3a fb e8 48 5a 02 fb 0f 0b 5b 41 5e c3 e8 3d 5a 02 fb <0f> 0b eb e1 66 0f 1f 84 00 00 00 00 00 55 41 57 41 56 41 55 41 54
RSP: 0018:ffffc90003387bc0 EFLAGS: 00010293
RAX: ffffffff867fd3e3 RBX: ffff88807e1ae800 RCX: ffff888078560000
RDX: 0000000000000000 RSI: ffff88807e1ae810 RDI: ffff888026574068
RBP: 1ffff11004cae98b R08: ffffffff8e210aef R09: 1ffffffff1c4215d
R10: dffffc0000000000 R11: fffffbfff1c4215e R12: ffff888026574068
R13: dffffc0000000000 R14: ffff888026574068 R15: ffff88807e1ae810
FS:  0000555578c1b500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe7339ae00 CR3: 000000007e321000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 gadgetfs_unbind+0x1a5/0x2a0 drivers/usb/gadget/legacy/inode.c:1656
 gadget_unbind_driver+0x1bb/0x3d0 drivers/usb/gadget/udc/core.c:1702
 device_remove drivers/base/dd.c:547 [inline]
 __device_release_driver drivers/base/dd.c:1279 [inline]
 device_release_driver_internal+0x47d/0x7c0 drivers/base/dd.c:1305
 driver_detach+0x1ef/0x2d0 drivers/base/dd.c:1368
 bus_remove_driver+0x11c/0x230 drivers/base/bus.c:679
 usb_gadget_unregister_driver+0x4a/0x70 drivers/usb/gadget/udc/core.c:1762
 dev_release+0x82/0x1f0 drivers/usb/gadget/legacy/inode.c:1194
 __fput+0x20a/0x8b0 fs/file_table.c:320
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f713419e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe7339c388 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffe7339c470 RCX: 00007f713419e019
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 0000000000020f2f R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2e720000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7134425fac R14: 00007f7134425fa8 R15: 00007f7134425fa0
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/02 11:01 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in dummy_free_request
2026/07/31 20:31 linux-6.1.y fb28aa725e05 7664cf44 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in dummy_free_request
* Struck through repros no longer work on HEAD.