* [syzbot] [usb?] WARNING in dummy_free_request (2)
@ 2026-07-29 0:10 syzbot
2026-08-02 0:10 ` syzbot
2026-11-06 14:55 ` Forwarded: [PATCH RFC] usb: gadget: gadgetfs: dequeue pending ep0 request before freeing syzbot
0 siblings, 2 replies; 3+ messages in thread
From: syzbot @ 2026-07-29 0:10 UTC (permalink / raw)
To: gregkh, linux-kernel, linux-usb, syzkaller-bugs
Hello,
syzbot found the following issue on:
HEAD commit: cc2b5f627e8c Add linux-next specific files for 20260714
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=159922a9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2290ccbf984c524f
dashboard link: https://syzkaller.appspot.com/bug?extid=c73e1942197af9f54ca3
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6836f8efb1da/disk-cc2b5f62.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/0109d3477cc7/vmlinux-cc2b5f62.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c2e49e350bbf/bzImage-cc2b5f62.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c73e1942197af9f54ca3@syzkaller.appspotmail.com
configfs-gadget.g1 gadget.0: uvc: uvc_function_bind()
configfs-gadget.g1 gadget.0: uvc: Unable to allocate streaming EP
------------[ cut here ]------------
!list_empty(&req->queue)
WARNING: drivers/usb/gadget/udc/dummy_hcd.c:691 at dummy_free_request+0x6f/0x80 drivers/usb/gadget/udc/dummy_hcd.c:691, CPU#1: syz.3.795/7609
Modules linked in:
CPU: 1 UID: 0 PID: 7609 Comm: syz.3.795 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)}
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:dummy_free_request+0x6f/0x80 drivers/usb/gadget/udc/dummy_hcd.c:691
Code: 75 22 e8 14 e0 8b fa 48 89 df 5b 41 5e e9 89 5c ec fa e8 04 e0 8b fa 90 0f 0b 90 5b 41 5e c3 cc cc cc cc cc e8 f2 df 8b fa 90 <0f> 0b 90 eb d8 66 66 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90
RSP: 0018:ffffc900087cf730 EFLAGS: 00010287
RAX: ffffffff8739c3be RBX: ffff88803a585ff0 RCX: 0000000000080000
RDX: ffffc9000759a000 RSI: 00000000000009d6 RDI: 00000000000009d7
RBP: 00000000ffffffea R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffffff8739c350 R12: ffff88805f2f0520
R13: ffff888021b808d8 R14: ffff8880295e00a8 R15: ffff8880295e0c98
FS: 00007f8a2e8b66c0(0000) GS:ffff888125af2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fc44f5ab050 CR3: 0000000024f34000 CR4: 00000000003526f0
Call Trace:
<TASK>
uvc_function_bind+0xe5d/0x15a0 drivers/usb/gadget/function/f_uvc.c:893
usb_add_function+0x290/0x930 drivers/usb/gadget/composite.c:333
configfs_composite_bind+0xde0/0x1410 drivers/usb/gadget/configfs.c:1802
gadget_bind_driver+0x2ca/0x9e0 drivers/usb/gadget/udc/core.c:1662
call_driver_probe drivers/base/dd.c:-1 [inline]
really_probe+0x254/0xae0 drivers/base/dd.c:706
__driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868
driver_probe_device+0x4f/0x240 drivers/base/dd.c:898
__driver_attach+0x339/0x600 drivers/base/dd.c:1292
bus_for_each_dev+0x23e/0x2c0 drivers/base/bus.c:383
bus_add_driver+0x348/0x670 drivers/base/bus.c:763
driver_register+0x23a/0x320 drivers/base/driver.c:174
usb_gadget_register_driver_owner+0xf9/0x270 drivers/usb/gadget/udc/core.c:1752
gadget_dev_desc_UDC_store+0x1c9/0x2f0 drivers/usb/gadget/configfs.c:300
flush_write_buffer fs/configfs/file.c:207 [inline]
configfs_write_iter+0x33a/0x430 fs/configfs/file.c:229
new_sync_write fs/read_write.c:595 [inline]
vfs_write+0x61e/0xbb0 fs/read_write.c:687
ksys_write+0x156/0x270 fs/read_write.c:739
do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
do_syscall_64+0x17b/0x530 arch/x86/entry/syscall_64.c:85
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8a3065de99
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:00007f8a2e8b6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f8a308e5fa0 RCX: 00007f8a3065de99
RDX: 000000000000000b RSI: 0000200000000880 RDI: 0000000000000003
RBP: 00007f8a306f3eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f8a308e6038 R14: 00007f8a308e5fa0 R15: 00007ffcfa6f54e8
</TASK>
---
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [syzbot] [usb?] WARNING in dummy_free_request (2) 2026-07-29 0:10 [syzbot] [usb?] WARNING in dummy_free_request (2) syzbot @ 2026-08-02 0:10 ` syzbot 2026-11-06 14:55 ` Forwarded: [PATCH RFC] usb: gadget: gadgetfs: dequeue pending ep0 request before freeing syzbot 1 sibling, 0 replies; 3+ messages in thread From: syzbot @ 2026-08-02 0:10 UTC (permalink / raw) To: gregkh, linux-kernel, linux-usb, syzkaller-bugs syzbot has found a reproducer for the following issue on: HEAD commit: e2d5e23967d0 Merge branch 'for-next/core' into for-kernelci git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci console output: https://syzkaller.appspot.com/x/log.txt?x=179d8649580000 kernel config: https://syzkaller.appspot.com/x/.config?x=72c97575381cec47 dashboard link: https://syzkaller.appspot.com/bug?extid=c73e1942197af9f54ca3 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 userspace arch: arm64 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13b62db9580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17a12c9e580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/294cdababe04/disk-e2d5e239.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/3e828c9fa51b/vmlinux-e2d5e239.xz kernel image: https://storage.googleapis.com/syzbot-assets/ffd7614ad310/Image-e2d5e239.gz.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c73e1942197af9f54ca3@syzkaller.appspotmail.com gadgetfs: suspended from state 3 gadgetfs: disconnected ------------[ cut here ]------------ WARNING: drivers/usb/gadget/udc/dummy_hcd.c:710 at dummy_free_request+0x7c/0x84 drivers/usb/gadget/udc/dummy_hcd.c:710, CPU#0: syz.0.32/4939 Modules linked in: CPU: 0 UID: 0 PID: 4939 Comm: syz.0.32 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026 pstate: 83400005 (Nzcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : dummy_free_request+0x7c/0x84 drivers/usb/gadget/udc/dummy_hcd.c:710 lr : dummy_free_request+0x7c/0x84 drivers/usb/gadget/udc/dummy_hcd.c:710 sp : ffff8000962579d0 x29: ffff8000962579d0 x28: 1fffe000195c4a01 x27: ffff0000cae25008 x26: 1fffe0001a0e2408 x25: 1fffe0001952998b x24: 1fffe000195299aa x23: dfff800000000000 x22: ffff800088b07eb8 x21: ffff800087332200 x20: ffff0000ca94c068 x19: ffff0000d866f900 x18: 0000000000000000 x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000 x14: 00000000868e5610 x13: 0000000000000001 x12: 0000000000000000 x11: ffff800080156ee8 x10: 0000000000000003 x9 : 0000000000000000 x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000 x5 : 0000000000000001 x4 : 0000000000000008 x3 : ffff8000835a7208 x2 : 0000000000000001 x1 : ffff0000c82cba80 x0 : 0000000000000000 Call trace: dummy_free_request+0x7c/0x84 drivers/usb/gadget/udc/dummy_hcd.c:710 (P) usb_ep_free_request+0x108/0x3fc drivers/usb/gadget/udc/core.c:221 gadgetfs_unbind+0x19c/0x1f0 drivers/usb/gadget/legacy/inode.c:1661 gadget_unbind_driver+0x188/0x790 drivers/usb/gadget/udc/core.c:1724 device_remove+0xc4/0x134 drivers/base/dd.c:616 __device_release_driver drivers/base/dd.c:1349 [inline] device_release_driver_internal+0x124/0x20c drivers/base/dd.c:1372 driver_detach+0x124/0x1b4 drivers/base/dd.c:1435 bus_remove_driver+0x124/0x22c drivers/base/bus.c:832 driver_unregister+0x78/0xac drivers/base/driver.c:202 usb_gadget_unregister_driver+0x50/0x78 drivers/usb/gadget/udc/core.c:1784 dev_release+0x8c/0x15c drivers/usb/gadget/legacy/inode.c:1198 __fput+0x338/0x74c fs/file_table.c:512 ____fput+0x20/0x30 fs/file_table.c:540 task_work_run+0x1cc/0x25c kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:70 [inline] exit_to_user_mode_loop+0x10c/0x17c kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] arm64_syscall_exit_to_user_mode arch/arm64/kernel/entry-common.c:88 [inline] el0_svc+0x18c/0x260 arch/arm64/kernel/entry-common.c:737 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 irq event stamp: 2192 hardirqs last enabled at (2191): [<ffff80008690a7dc>] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:187 [inline] hardirqs last enabled at (2191): [<ffff80008690a7dc>] _raw_spin_unlock_irq+0x30/0x80 kernel/locking/spinlock.c:206 hardirqs last disabled at (2192): [<ffff8000868e5428>] el1_brk64+0x20/0x54 arch/arm64/kernel/entry-common.c:425 softirqs last enabled at (1170): [<ffff80008030ff18>] softirq_handle_end kernel/softirq.c:468 [inline] softirqs last enabled at (1170): [<ffff80008030ff18>] handle_softirqs+0xc28/0xd98 kernel/softirq.c:650 softirqs last disabled at (1161): [<ffff8000800204c0>] __do_softirq+0x14/0x20 kernel/softirq.c:656 ---[ end trace 0000000000000000 ]--- ================================================================== BUG: KASAN: slab-use-after-free in __list_del_entry_valid_or_report+0x3c/0x1b8 lib/list_debug.c:49 Read of size 8 at addr ffff0000d866f908 by task syz.0.32/4939 CPU: 1 UID: 0 PID: 4939 Comm: syz.0.32 Tainted: G W syzkaller #0 PREEMPT Tainted: [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 print_address_description+0xb0/0x238 mm/kasan/report.c:378 print_report+0x68/0x84 mm/kasan/report.c:482 kasan_report+0x8c/0xc4 mm/kasan/report.c:595 __asan_report_load8_noabort+0x20/0x2c mm/kasan/report_generic.c:381 __list_del_entry_valid_or_report+0x3c/0x1b8 lib/list_debug.c:49 __list_del_entry_valid include/linux/list.h:132 [inline] __list_del_entry include/linux/list.h:246 [inline] list_del_init include/linux/list.h:318 [inline] nuke+0x60/0x194 drivers/usb/gadget/udc/dummy_hcd.c:360 stop_activity drivers/usb/gadget/udc/dummy_hcd.c:379 [inline] dummy_udc_stop+0xe4/0x180 drivers/usb/gadget/udc/dummy_hcd.c:1057 usb_gadget_udc_stop_locked drivers/usb/gadget/udc/core.c:1265 [inline] gadget_unbind_driver+0x204/0x790 drivers/usb/gadget/udc/core.c:1727 device_remove+0xc4/0x134 drivers/base/dd.c:616 __device_release_driver drivers/base/dd.c:1349 [inline] device_release_driver_internal+0x124/0x20c drivers/base/dd.c:1372 driver_detach+0x124/0x1b4 drivers/base/dd.c:1435 bus_remove_driver+0x124/0x22c drivers/base/bus.c:832 driver_unregister+0x78/0xac drivers/base/driver.c:202 usb_gadget_unregister_driver+0x50/0x78 drivers/usb/gadget/udc/core.c:1784 dev_release+0x8c/0x15c drivers/usb/gadget/legacy/inode.c:1198 __fput+0x338/0x74c fs/file_table.c:512 ____fput+0x20/0x30 fs/file_table.c:540 task_work_run+0x1cc/0x25c kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:70 [inline] exit_to_user_mode_loop+0x10c/0x17c kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] arm64_syscall_exit_to_user_mode arch/arm64/kernel/entry-common.c:88 [inline] el0_svc+0x18c/0x260 arch/arm64/kernel/entry-common.c:737 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 Allocated by task 4939: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:78 kasan_save_alloc_info+0x44/0x54 mm/kasan/generic.c:570 poison_kmalloc_redzone mm/kasan/common.c:398 [inline] __kasan_kmalloc+0x9c/0xb4 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline] __kmalloc_cache_noprof+0x2e8/0x5ec mm/slub.c:5489 _kmalloc_noprof include/linux/slab.h:988 [inline] _kzalloc_noprof include/linux/slab.h:1309 [inline] dummy_alloc_request+0x88/0x128 drivers/usb/gadget/udc/dummy_hcd.c:693 usb_ep_alloc_request+0x74/0x480 drivers/usb/gadget/udc/core.c:197 gadgetfs_bind+0x104/0x75c drivers/usb/gadget/legacy/inode.c:1686 gadget_bind_driver+0x274/0x834 drivers/usb/gadget/udc/core.c:1662 call_driver_probe drivers/base/dd.c:-1 [inline] really_probe+0x29c/0x800 drivers/base/dd.c:706 __driver_probe_device+0x1e0/0x350 drivers/base/dd.c:868 driver_probe_device+0x6c/0x19c drivers/base/dd.c:898 __driver_attach+0x168/0x384 drivers/base/dd.c:1292 bus_for_each_dev+0x128/0x1b4 drivers/base/bus.c:383 driver_attach+0x50/0x60 drivers/base/dd.c:1310 bus_add_driver+0x208/0x500 drivers/base/bus.c:763 driver_register+0x220/0x310 drivers/base/driver.c:174 usb_gadget_register_driver_owner+0xf0/0x25c drivers/usb/gadget/udc/core.c:1752 dev_config+0x91c/0xcc0 drivers/usb/gadget/legacy/inode.c:1883 vfs_write+0x2a4/0xa0c fs/read_write.c:685 ksys_write+0x12c/0x228 fs/read_write.c:739 __do_sys_write fs/read_write.c:750 [inline] __se_sys_write fs/read_write.c:747 [inline] __arm64_sys_write+0x7c/0x90 fs/read_write.c:747 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 Freed by task 4939: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x40/0x78 mm/kasan/common.c:78 kasan_save_free_info+0x58/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x74/0xa4 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2677 [inline] slab_free mm/slub.c:6377 [inline] kfree+0x188/0x690 mm/slub.c:6692 dummy_free_request+0x5c/0x84 drivers/usb/gadget/udc/dummy_hcd.c:711 usb_ep_free_request+0x108/0x3fc drivers/usb/gadget/udc/core.c:221 gadgetfs_unbind+0x19c/0x1f0 drivers/usb/gadget/legacy/inode.c:1661 gadget_unbind_driver+0x188/0x790 drivers/usb/gadget/udc/core.c:1724 device_remove+0xc4/0x134 drivers/base/dd.c:616 __device_release_driver drivers/base/dd.c:1349 [inline] device_release_driver_internal+0x124/0x20c drivers/base/dd.c:1372 driver_detach+0x124/0x1b4 drivers/base/dd.c:1435 bus_remove_driver+0x124/0x22c drivers/base/bus.c:832 driver_unregister+0x78/0xac drivers/base/driver.c:202 usb_gadget_unregister_driver+0x50/0x78 drivers/usb/gadget/udc/core.c:1784 dev_release+0x8c/0x15c drivers/usb/gadget/legacy/inode.c:1198 __fput+0x338/0x74c fs/file_table.c:512 ____fput+0x20/0x30 fs/file_table.c:540 task_work_run+0x1cc/0x25c kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:70 [inline] exit_to_user_mode_loop+0x10c/0x17c kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] arm64_syscall_exit_to_user_mode arch/arm64/kernel/entry-common.c:88 [inline] el0_svc+0x18c/0x260 arch/arm64/kernel/entry-common.c:737 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 The buggy address belongs to the object at ffff0000d866f900 which belongs to the cache kmalloc-128 of size 128 The buggy address is located 8 bytes inside of freed 128-byte region [ffff0000d866f900, ffff0000d866f980) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11866f flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff) page_type: f5(slab) raw: 05ffc00000000000 ffff0000c0001a00 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800100010 00000000f5000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff0000d866f800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff0000d866f880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff0000d866f900: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff0000d866f980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff0000d866fa00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== list_del corruption, ffff0000d866f900->next is NULL ------------[ cut here ]------------ kernel BUG at lib/list_debug.c:53! Internal error: Oops - BUG: 00000000f2000800 [#1] SMP Modules linked in: CPU: 1 UID: 0 PID: 4939 Comm: syz.0.32 Tainted: G B W syzkaller #0 PREEMPT Tainted: [B]=BAD_PAGE, [W]=WARN Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026 pstate: 634000c5 (nZCv daIF +PAN -UAO +TCO +DIT -SSBS BTYPE=--) pc : __list_del_entry_valid_or_report+0xec/0x1b8 lib/list_debug.c:52 lr : __list_del_entry_valid_or_report+0xec/0x1b8 lib/list_debug.c:52 sp : ffff8000962579c0 x29: ffff8000962579c0 x28: 1fffe000195c4a01 x27: ffff0000cae25008 x26: 1fffe000195c4a00 x25: 00000000ffffff94 x24: 1fffe00019529808 x23: dfff800000000000 x22: dfff800000000000 x21: 0338032e0000134b x20: 0000000000000000 x19: ffff0000d866f900 x18: 0000000000000000 x17: 3d3d3d3d3d3d3d3d x16: 3d3d3d3d3d3d3d3d x15: 3d3d3d3d3d3d3d3d x14: 3d3d3d3d3d3d3d3d x13: 0000000000000001 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000002 x9 : bfb6b4227df68700 x8 : bfb6b4227df68700 x7 : 0000000000000001 x6 : ffff80008048de94 x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff800080498bc8 x2 : 0000000100000001 x1 : ffff0000c82cba80 x0 : 0000000000000033 Call trace: __list_del_entry_valid_or_report+0xec/0x1b8 lib/list_debug.c:52 (P) __list_del_entry_valid include/linux/list.h:132 [inline] __list_del_entry include/linux/list.h:246 [inline] list_del_init include/linux/list.h:318 [inline] nuke+0x60/0x194 drivers/usb/gadget/udc/dummy_hcd.c:360 stop_activity drivers/usb/gadget/udc/dummy_hcd.c:379 [inline] dummy_udc_stop+0xe4/0x180 drivers/usb/gadget/udc/dummy_hcd.c:1057 usb_gadget_udc_stop_locked drivers/usb/gadget/udc/core.c:1265 [inline] gadget_unbind_driver+0x204/0x790 drivers/usb/gadget/udc/core.c:1727 device_remove+0xc4/0x134 drivers/base/dd.c:616 __device_release_driver drivers/base/dd.c:1349 [inline] device_release_driver_internal+0x124/0x20c drivers/base/dd.c:1372 driver_detach+0x124/0x1b4 drivers/base/dd.c:1435 bus_remove_driver+0x124/0x22c drivers/base/bus.c:832 driver_unregister+0x78/0xac drivers/base/driver.c:202 usb_gadget_unregister_driver+0x50/0x78 drivers/usb/gadget/udc/core.c:1784 dev_release+0x8c/0x15c drivers/usb/gadget/legacy/inode.c:1198 __fput+0x338/0x74c fs/file_table.c:512 ____fput+0x20/0x30 fs/file_table.c:540 task_work_run+0x1cc/0x25c kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:70 [inline] exit_to_user_mode_loop+0x10c/0x17c kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] arm64_syscall_exit_to_user_mode arch/arm64/kernel/entry-common.c:88 [inline] el0_svc+0x18c/0x260 arch/arm64/kernel/entry-common.c:737 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 Code: f0029ac0 91328000 aa1303e1 979c21eb (d4210000) ---[ end trace 0000000000000000 ]--- --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. ^ permalink raw reply [flat|nested] 3+ messages in thread
* Forwarded: [PATCH RFC] usb: gadget: gadgetfs: dequeue pending ep0 request before freeing 2026-07-29 0:10 [syzbot] [usb?] WARNING in dummy_free_request (2) syzbot 2026-08-02 0:10 ` syzbot @ 2026-11-06 14:55 ` syzbot 1 sibling, 0 replies; 3+ messages in thread From: syzbot @ 2026-11-06 14:55 UTC (permalink / raw) To: linux-kernel For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org. *** Subject: [PATCH RFC] usb: gadget: gadgetfs: dequeue pending ep0 request before freeing Author: devnull@kernel.org From: Jing Lin <kayano050408@gmail.com> Please test this gadgetfs ep0 request lifetime fix The unpatched base reproduces the warning and use-after-free locally on arm64 QEMU with dummy_hcd and KASAN #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git f66469d9905b39d2c260a15d7d6db450f4db67c1 gadgetfs_unbind() frees the preallocated ep0 request after disconnecting the gadget, assuming that no I/O remains active With dummy_hcd, disconnecting does not necessarily drain ep0, so a delayed userspace response can leave dev->req queued when it is freed This triggers the warning in dummy_free_request() and a use-after-free when dummy_udc_stop() subsequently drains the endpoint queue Track dev->req from submission through completion under dev->lock and reject reuse while it is busy After waiting for active UDC users to finish, dequeue a pending request before freeing it and clearing ep0->driver_data Drop dev->lock around dequeue because the completion callback takes it Only dequeue pending requests to avoid errors from UDCs that reject cancellation of an unqueued request Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+c73e1942197af9f54ca3@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=c73e1942197af9f54ca3 Signed-off-by: Jing Lin <kayano050408@gmail.com> --- Local validation on arm64 QEMU with dummy_hcd, KASAN and lockdep: - The unpatched kernel reproduces the warning and use-after-free - The patched kernel runs the C reproducer and rebind/concurrency workload without the warning, a KASAN report or a lockdep report - W=1 compilation of inode.o and the Image build completed successfully AI tools assisted with patch development, the commit description, review and local QEMU validation Related syzbot RFC: https://lore.kernel.org/all/161c70c4-a363-469d-8665-64f71763f84b@mail.kernel.org/ This version tracks pending requests and guards reuse while they are busy --- drivers/usb/gadget/legacy/inode.c | 55 ++++++++++++++++++++++++++++++++------- 1 file changed, 46 insertions(+), 9 deletions(-) diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c index 7f6d84601..d60df4ad3 100644 --- a/drivers/usb/gadget/legacy/inode.c +++ b/drivers/usb/gadget/legacy/inode.c @@ -140,6 +140,7 @@ struct dev_data { setup_abort : 1, gadget_registered : 1; unsigned setup_wLength; + bool ep0_req_queued; /* the rest is basically write-once */ struct usb_config_descriptor *config, *hs_config; @@ -984,6 +985,16 @@ static inline void ep0_readable (struct dev_data *dev) kill_fasync (&dev->fasync, SIGIO, POLL_IN); } +static void dev_req_complete(struct usb_ep *ep, struct usb_request *req) +{ + struct dev_data *dev = ep->driver_data; + unsigned long flags; + + spin_lock_irqsave(&dev->lock, flags); + dev->ep0_req_queued = false; + spin_unlock_irqrestore(&dev->lock, flags); +} + static void clean_req (struct usb_ep *ep, struct usb_request *req) { struct dev_data *dev = ep->driver_data; @@ -992,7 +1003,7 @@ static void clean_req (struct usb_ep *ep, struct usb_request *req) kfree(req->buf); req->buf = dev->rbuf; } - req->complete = epio_complete; + req->complete = dev_req_complete; dev->setup_out_ready = 0; } @@ -1004,6 +1015,7 @@ static void ep0_complete (struct usb_ep *ep, struct usb_request *req) /* for control OUT, data must still get to userspace */ spin_lock_irqsave(&dev->lock, flags); + dev->ep0_req_queued = false; if (!dev->setup_in) { dev->setup_out_error = (req->status != 0); if (!dev->setup_out_error) @@ -1015,7 +1027,7 @@ static void ep0_complete (struct usb_ep *ep, struct usb_request *req) /* clean up as appropriate */ if (free && req->buf != &dev->rbuf) clean_req (ep, req); - req->complete = epio_complete; + req->complete = dev_req_complete; spin_unlock_irqrestore(&dev->lock, flags); } @@ -1023,7 +1035,7 @@ static int setup_req (struct usb_ep *ep, struct usb_request *req, u16 len) { struct dev_data *dev = ep->driver_data; - if (dev->setup_out_ready) { + if (dev->setup_out_ready || dev->ep0_req_queued) { DBG (dev, "ep0 request busy!\n"); return -EBUSY; } @@ -1073,13 +1085,20 @@ ep0_read (struct file *fd, char __user *buf, size_t len, loff_t *ptr) struct usb_request *req = dev->req; if ((retval = setup_req (ep, req, 0)) == 0) { + dev->state = STATE_DEV_CONNECTED; + dev->ep0_req_queued = true; ++dev->udc_usage; spin_unlock_irq (&dev->lock); retval = usb_ep_queue (ep, req, GFP_KERNEL); spin_lock_irq (&dev->lock); --dev->udc_usage; + if (retval < 0) { + dev->ep0_req_queued = false; + clean_req(ep, req); + } + } else { + dev->state = STATE_DEV_CONNECTED; } - dev->state = STATE_DEV_CONNECTED; /* assume that was SET_CONFIGURATION */ if (dev->current_config) { @@ -1270,6 +1289,7 @@ ep0_write (struct file *fd, const char __user *buf, size_t len, loff_t *ptr) retval = setup_req (dev->gadget->ep0, dev->req, len); if (retval == 0) { dev->state = STATE_DEV_CONNECTED; + dev->ep0_req_queued = true; ++dev->udc_usage; spin_unlock_irq (&dev->lock); if (copy_from_user (dev->req->buf, buf, len)) @@ -1284,6 +1304,7 @@ ep0_write (struct file *fd, const char __user *buf, size_t len, loff_t *ptr) spin_lock_irq(&dev->lock); --dev->udc_usage; if (retval < 0) { + dev->ep0_req_queued = false; clean_req (dev->gadget->ep0, dev->req); } else retval = len; @@ -1508,6 +1529,11 @@ gadgetfs_setup (struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl) } else if (dev->state == STATE_DEV_SETUP) dev->setup_abort = 1; + if (dev->ep0_req_queued) { + spin_unlock(&dev->lock); + return -EBUSY; + } + req->buf = dev->rbuf; req->context = NULL; switch (ctrl->bRequest) { @@ -1626,6 +1652,7 @@ gadgetfs_setup (struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl) if (value < 0) break; + dev->ep0_req_queued = true; ++dev->udc_usage; spin_unlock (&dev->lock); value = usb_ep_queue (gadget->ep0, dev->req, @@ -1633,6 +1660,7 @@ gadgetfs_setup (struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl) spin_lock (&dev->lock); --dev->udc_usage; if (value < 0) { + dev->ep0_req_queued = false; clean_req (gadget->ep0, dev->req); break; } @@ -1664,16 +1692,18 @@ gadgetfs_setup (struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl) req->length = value; req->zero = value < w_length; + dev->ep0_req_queued = true; ++dev->udc_usage; spin_unlock (&dev->lock); value = usb_ep_queue (gadget->ep0, req, GFP_KERNEL); spin_lock(&dev->lock); --dev->udc_usage; - spin_unlock(&dev->lock); if (value < 0) { + dev->ep0_req_queued = false; DBG (dev, "ep_queue --> %d\n", value); req->status = 0; } + spin_unlock(&dev->lock); return value; } @@ -1771,6 +1801,7 @@ static void gadgetfs_unbind (struct usb_gadget *gadget) { struct dev_data *dev = get_gadget_data (gadget); + bool queued; DBG (dev, "%s\n", __func__); @@ -1781,15 +1812,20 @@ gadgetfs_unbind (struct usb_gadget *gadget) usleep_range(1000, 2000); spin_lock_irq(&dev->lock); } + queued = dev->ep0_req_queued; spin_unlock_irq (&dev->lock); + if (dev->req) { + if (queued) + usb_ep_dequeue(gadget->ep0, dev->req); + usb_ep_free_request(gadget->ep0, dev->req); + dev->req = NULL; + } + destroy_ep_files (dev); gadget->ep0->driver_data = NULL; set_gadget_data (gadget, NULL); - /* we've already been disconnected ... no i/o is active */ - if (dev->req) - usb_ep_free_request (gadget->ep0, dev->req); DBG (dev, "%s done\n", __func__); put_dev (dev); } @@ -1816,11 +1852,12 @@ static int gadgetfs_bind(struct usb_gadget *gadget, get_dev (dev); /* preallocate control response and buffer */ + dev->ep0_req_queued = false; dev->req = usb_ep_alloc_request (gadget->ep0, GFP_KERNEL); if (!dev->req) goto enomem; dev->req->context = NULL; - dev->req->complete = epio_complete; + dev->req->complete = dev_req_complete; if (activate_ep_files (dev) < 0) goto enomem; --- base-commit: f66469d9905b39d2c260a15d7d6db450f4db67c1 change-id: 20261106-b4-gadgetfs-ep0-f814c14717a9 Best regards, -- Jing Lin <kayano050408@gmail.com> ^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2026-11-06 14:55 UTC | newest] Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2026-07-29 0:10 [syzbot] [usb?] WARNING in dummy_free_request (2) syzbot 2026-08-02 0:10 ` syzbot 2026-11-06 14:55 ` Forwarded: [PATCH RFC] usb: gadget: gadgetfs: dequeue pending ep0 request before freeing syzbot
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