WARNING in ttusb_dec_start_feed

Status: upstream: reported C repro on 2026/08/09 19:13
Subsystems: media usb
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+e1dbaae5eefaa2dfbc35@syzkaller.appspotmail.com
First crash: 2d02h, last: 1d18h
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ID Workflow Result Correct Bug Created Started Finished Revision
478f044d assessment-security DenialOfService: ✅ Exploitable: ✅ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ WARNING in ttusb_dec_start_feed 2026/08/08 22:50 2026/08/08 22:50 2026/08/08 23:13 5d63f80b
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[syzbot] [media?] [usb?] WARNING in ttusb_dec_start_feed 0 (1) 2026/08/09 19:13

Sample crash report:
usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
------------[ cut here ]------------
memcpy: detected buffer overflow: 75 byte read of buffer size 60
WARNING: lib/string_helpers.c:1037 at __fortify_report+0xa0/0xb8 lib/string_helpers.c:1036, CPU#1: kworker/1:3/4388
Modules linked in:
CPU: 1 UID: 0 PID: 4388 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
Workqueue: usb_hub_wq hub_event
pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __fortify_report+0xa0/0xb8 lib/string_helpers.c:1036
lr : __fortify_report+0xa0/0xb8 lib/string_helpers.c:1036
sp : ffff800094c46d20
x29: ffff800094c46d20 x28: dfff800000000000 x27: ffff700012988db0
x26: 0000000000000000 x25: ffff0000d18d4983 x24: ffff800094c46ea0
x23: 000000000000004b x22: ffff800086cec898 x21: 0000000000000000
x20: 000000000000004b x19: 000000000000003c x18: 1fffe00034bbbe28
x17: 0000000000000003 x16: ffff800088b27000 x15: ffff8000824ebed4
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000002 x9 : 96b32e65f1701e00
x8 : 96b32e65f1701e00 x7 : ffff80008048e8f8 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000802f8870
x2 : 0000000100000000 x1 : ffff0000c70e1d40 x0 : 0000000000000000
Call trace:
 __fortify_report+0xa0/0xb8 lib/string_helpers.c:1036 (P)
 __fortify_panic+0x10/0x14 lib/string_helpers.c:1043
 fortify_memcpy_chk include/linux/fortify-string.h:549 [inline]
 ttusb_dec_start_feed+0x0/0x10ac drivers/media/usb/ttusb-dec/ttusb_dec.c:372
 ttusb_dec_get_stb_state drivers/media/usb/ttusb-dec/ttusb_dec.c:392 [inline]
 ttusb_dec_init_stb drivers/media/usb/ttusb-dec/ttusb_dec.c:1413 [inline]
 ttusb_dec_probe+0x724/0x1aa0 drivers/media/usb/ttusb-dec/ttusb_dec.c:1671
 usb_probe_interface+0x308/0x788 drivers/usb/core/driver.c:396
 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
 __device_attach_driver+0x198/0x2f8 drivers/base/dd.c:1026
 bus_for_each_drv+0x144/0x1dc drivers/base/bus.c:500
 __device_attach+0x248/0x390 drivers/base/dd.c:1098
 device_initial_probe+0x90/0xc8 drivers/base/dd.c:1153
 bus_probe_device+0x58/0x120 drivers/base/bus.c:620
 device_add+0x6cc/0x9e0 drivers/base/core.c:3772
 usb_set_configuration+0x1184/0x158c drivers/usb/core/message.c:2268
 usb_generic_driver_probe+0x8c/0x148 drivers/usb/core/generic.c:250
 usb_probe_device+0x114/0x2b0 drivers/usb/core/driver.c:291
 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
 __device_attach_driver+0x198/0x2f8 drivers/base/dd.c:1026
 bus_for_each_drv+0x144/0x1dc drivers/base/bus.c:500
 __device_attach+0x248/0x390 drivers/base/dd.c:1098
 device_initial_probe+0x90/0xc8 drivers/base/dd.c:1153
 bus_probe_device+0x58/0x120 drivers/base/bus.c:620
 device_add+0x6cc/0x9e0 drivers/base/core.c:3772
 usb_new_device+0x9bc/0x11f0 drivers/usb/core/hub.c:2695
 hub_port_connect drivers/usb/core/hub.c:5567 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x1ef0/0x39fc drivers/usb/core/hub.c:5953
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0x788/0x10b8 kernel/workqueue.c:3405
 worker_thread+0x798/0xbd0 kernel/workqueue.c:3486
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
irq event stamp: 7958
hardirqs last  enabled at (7957): [<ffff8000868f4e64>] irqentry_exit_to_kernel_mode_after_preempt include/linux/irq-entry-common.h:507 [inline]
hardirqs last  enabled at (7957): [<ffff8000868f4e64>] arm64_exit_to_kernel_mode+0x80/0x94 arch/arm64/kernel/entry-common.c:62
hardirqs last disabled at (7958): [<ffff8000868f0d88>] el1_brk64+0x20/0x54 arch/arm64/kernel/entry-common.c:425
softirqs last  enabled at (7892): [<ffff800080310744>] softirq_handle_end kernel/softirq.c:468 [inline]
softirqs last  enabled at (7892): [<ffff800080310744>] handle_softirqs+0xc28/0xd98 kernel/softirq.c:650
softirqs last disabled at (7883): [<ffff8000800204c0>] __do_softirq+0x14/0x20 kernel/softirq.c:656
---[ end trace 0000000000000000 ]---
------------[ cut here ]------------
kernel BUG at lib/string_helpers.c:1044!
Internal error: Oops - BUG: 00000000f2000800 [#1]  SMP
Modules linked in:
CPU: 1 UID: 0 PID: 4388 Comm: kworker/1:3 Tainted: G        W           syzkaller #0 PREEMPT 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
Workqueue: usb_hub_wq hub_event
pstate: 63400005 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : __fortify_panic+0x10/0x14 lib/string_helpers.c:1043
lr : __fortify_panic+0x10/0x14 lib/string_helpers.c:1043
sp : ffff800094c46d50
x29: ffff800094c46d50 x28: dfff800000000000 x27: ffff700012988db0
x26: 0000000000000000 x25: ffff0000d18d4983 x24: ffff800094c46ea0
x23: 000000000000004b x22: 000000000000004b x21: ffff0000d18d4980
x20: 1fffe0001a31a930 x19: ffff0000dd4bc000 x18: 1fffe00034bbbe28
x17: 0000000000000003 x16: ffff800088b27000 x15: ffff8000824ebed4
x14: 0000000000000000 x13: 0000000000000001 x12: 0000000000000000
x11: 0000000000000000 x10: 0000000000000002 x9 : 96b32e65f1701e00
x8 : 96b32e65f1701e00 x7 : ffff80008048e8f8 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000802f8870
x2 : 0000000100000000 x1 : ffff0000c70e1d40 x0 : 0000000000000000
Call trace:
 __fortify_panic+0x10/0x14 lib/string_helpers.c:1043 (P)
 fortify_memcpy_chk include/linux/fortify-string.h:549 [inline]
 ttusb_dec_start_feed+0x0/0x10ac drivers/media/usb/ttusb-dec/ttusb_dec.c:372
 ttusb_dec_get_stb_state drivers/media/usb/ttusb-dec/ttusb_dec.c:392 [inline]
 ttusb_dec_init_stb drivers/media/usb/ttusb-dec/ttusb_dec.c:1413 [inline]
 ttusb_dec_probe+0x724/0x1aa0 drivers/media/usb/ttusb-dec/ttusb_dec.c:1671
 usb_probe_interface+0x308/0x788 drivers/usb/core/driver.c:396
 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
 __device_attach_driver+0x198/0x2f8 drivers/base/dd.c:1026
 bus_for_each_drv+0x144/0x1dc drivers/base/bus.c:500
 __device_attach+0x248/0x390 drivers/base/dd.c:1098
 device_initial_probe+0x90/0xc8 drivers/base/dd.c:1153
 bus_probe_device+0x58/0x120 drivers/base/bus.c:620
 device_add+0x6cc/0x9e0 drivers/base/core.c:3772
 usb_set_configuration+0x1184/0x158c drivers/usb/core/message.c:2268
 usb_generic_driver_probe+0x8c/0x148 drivers/usb/core/generic.c:250
 usb_probe_device+0x114/0x2b0 drivers/usb/core/driver.c:291
 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
 __device_attach_driver+0x198/0x2f8 drivers/base/dd.c:1026
 bus_for_each_drv+0x144/0x1dc drivers/base/bus.c:500
 __device_attach+0x248/0x390 drivers/base/dd.c:1098
 device_initial_probe+0x90/0xc8 drivers/base/dd.c:1153
 bus_probe_device+0x58/0x120 drivers/base/bus.c:620
 device_add+0x6cc/0x9e0 drivers/base/core.c:3772
 usb_new_device+0x9bc/0x11f0 drivers/usb/core/hub.c:2695
 hub_port_connect drivers/usb/core/hub.c:5567 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x1ef0/0x39fc drivers/usb/core/hub.c:5953
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0x788/0x10b8 kernel/workqueue.c:3405
 worker_thread+0x798/0xbd0 kernel/workqueue.c:3486
 kthread+0x304/0x3d4 kernel/kthread.c:436
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:838
Code: d503233f a9bf7bfd 910003fd 94619c95 (d4210000) 
---[ end trace 0000000000000000 ]---

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/08 19:26 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci ba5cc80fd326 5d63f80b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING in ttusb_dec_start_feed
2026/08/09 03:44 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci ba5cc80fd326 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 WARNING in ttusb_dec_start_feed
* Struck through repros no longer work on HEAD.