* [BUG] ALSA: usb: 6fire: KASAN slab-use-after-free in dummy_timer
@ 2026-07-24 3:07 Shuangpeng Bai
2026-07-24 7:45 ` Takashi Iwai
0 siblings, 1 reply; 2+ messages in thread
From: Shuangpeng Bai @ 2026-07-24 3:07 UTC (permalink / raw)
To: Jaroslav Kysela, Takashi Iwai
Cc: Shuangpeng Bai, Kees Cook, linux-sound, linux-kernel
Hi Kernel Maintainers,
I hit the following report while testing current upstream kernel:
KASAN: slab-use-after-free in dummy_timer
on commit: fce2dfa773ced15f27dd27cd0b482a7473cdcf2a (2026-07-16)
The reproducer and .config files are here.
https://gist.github.com/shuangpengbai/a410bc05b4f22d1ba4ce7ef059043fea
I'm happy to test debug patches or provide additional information.
Reported-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
[ 400.891255][ C0] BUG: KASAN: slab-use-after-free in dummy_timer (drivers/usb/common/usb-otg-fsm.c:393)
[ 400.891273][ C0] Read of size 4 at addr ffff8881789bc20c by task kworker/0:2/773
[ 400.891276][ C0]
[ 400.891291][ C0] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 400.891294][ C0] Workqueue: usb_hub_wq hub_event
[ 400.891299][ C0] Call Trace:
[ 400.891301][ C0] <IRQ>
[ 400.891302][ C0] dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
[ 400.891306][ C0] print_report (mm/kasan/report.c:378 mm/kasan/report.c:482)
[ 400.891322][ C0] kasan_report (mm/kasan/report.c:595)
[ 400.891330][ C0] dummy_timer (drivers/usb/common/usb-otg-fsm.c:393)
[ 400.891397][ C0] __hrtimer_run_queues (kernel/time/hrtimer.c:2032 kernel/time/hrtimer.c:2096)
[ 400.891403][ C0] hrtimer_run_softirq (kernel/time/hrtimer.c:2113)
[ 400.891414][ C0] handle_softirqs (kernel/softirq.c:622)
[ 400.891420][ C0] __irq_exit_rcu (kernel/softirq.c:656 kernel/softirq.c:496 kernel/softirq.c:735)
[ 400.891423][ C0] sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1062 arch/x86/kernel/apic/apic.c:1062)
[ 400.891427][ C0] </IRQ>
[ 400.891428][ C0] <TASK>
[ 400.891579][ C0] really_probe (drivers/base/dd.c:644 drivers/base/dd.c:706)
[ 400.891582][ C0] __driver_probe_device (drivers/base/dd.c:868)
[ 400.891585][ C0] driver_probe_device (drivers/base/dd.c:898)
[ 400.891588][ C0] __device_attach_driver (drivers/base/dd.c:1026)
[ 400.891593][ C0] bus_for_each_drv (drivers/base/bus.c:500)
[ 400.891615][ C0] __device_attach (drivers/base/dd.c:1098)
[ 400.891631][ C0] device_initial_probe (drivers/base/dd.c:1153)
[ 400.891634][ C0] bus_probe_device (drivers/base/bus.c:620)
[ 400.891637][ C0] device_add (drivers/base/core.c:3772)
[ 400.891641][ C0] usb_set_configuration (drivers/usb/core/message.c:2268)
[ 400.891647][ C0] usb_generic_driver_probe (drivers/usb/core/generic.c:250)
[ 400.891651][ C0] usb_probe_device (drivers/usb/core/driver.c:291)
[ 400.891653][ C0] really_probe (drivers/base/dd.c:? drivers/base/dd.c:706)
[ 400.891656][ C0] __driver_probe_device (drivers/base/dd.c:868)
[ 400.891663][ C0] driver_probe_device (drivers/base/dd.c:898)
[ 400.891665][ C0] __device_attach_driver (drivers/base/dd.c:1026)
[ 400.891671][ C0] bus_for_each_drv (drivers/base/bus.c:500)
[ 400.891685][ C0] __device_attach (drivers/base/dd.c:1098)
[ 400.891704][ C0] device_initial_probe (drivers/base/dd.c:1153)
[ 400.891707][ C0] bus_probe_device (drivers/base/bus.c:620)
[ 400.891710][ C0] device_add (drivers/base/core.c:3772)
[ 400.891714][ C0] usb_new_device (drivers/usb/core/hub.c:2695)
[ 400.891726][ C0] hub_event (drivers/usb/core/hub.c:5567 drivers/usb/core/hub.c:5707 drivers/usb/core/hub.c:5871 drivers/usb/core/hub.c:5953)
[ 400.891743][ C0] process_scheduled_works (kernel/workqueue.c:3322 kernel/workqueue.c:3405)
[ 400.891748][ C0] worker_thread (kernel/workqueue.c:3486)
[ 400.891756][ C0] kthread (kernel/kthread.c:436)
[ 400.891764][ C0] ret_from_fork (arch/x86/kernel/process.c:158)
[ 400.891790][ C0] ret_from_fork_asm (arch/x86/entry/entry_64.S:245)
[ 400.891795][ C0] </TASK>
[ 400.891797][ C0] Freed by task 773 on cpu 0 at 400.890164s:
[ 400.891805][ C0] kasan_save_track (mm/kasan/common.c:57 mm/kasan/common.c:78)
[ 400.891813][ C0] kasan_save_free_info (mm/kasan/generic.c:584)
[ 400.891821][ C0] __kasan_slab_free (mm/kasan/common.c:253 mm/kasan/common.c:285)
[ 400.891824][ C0] kfree (./include/linux/kasan.h:235 mm/slub.c:2705 mm/slub.c:6405 mm/slub.c:6720)
[ 400.891827][ C0] usb6fire_comm_destroy (sound/usb/6fire/comm.c:197)
[ 400.891830][ C0] usb6fire_card_free (sound/usb/6fire/chip.c:65)
[ 400.891832][ C0] release_card_device (sound/core/init.c:594 sound/core/init.c:153)
[ 400.891852][ C0] kobject_put (lib/kobject.c:689 lib/kobject.c:720 ./include/linux/kref.h:65 lib/kobject.c:737)
[ 400.891855][ C0] snd_card_free (sound/core/init.c:626 sound/core/init.c:658)
[ 400.891858][ C0] usb6fire_chip_probe (sound/usb/6fire/chip.c:153)
[ 400.891860][ C0] usb_probe_interface (drivers/usb/core/driver.c:396)
Best,
Shuangpeng
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [BUG] ALSA: usb: 6fire: KASAN slab-use-after-free in dummy_timer
2026-07-24 3:07 [BUG] ALSA: usb: 6fire: KASAN slab-use-after-free in dummy_timer Shuangpeng Bai
@ 2026-07-24 7:45 ` Takashi Iwai
0 siblings, 0 replies; 2+ messages in thread
From: Takashi Iwai @ 2026-07-24 7:45 UTC (permalink / raw)
To: Shuangpeng Bai
Cc: Jaroslav Kysela, Takashi Iwai, Kees Cook, linux-sound,
linux-kernel
On Fri, 24 Jul 2026 05:07:50 +0200,
Shuangpeng Bai wrote:
>
> Hi Kernel Maintainers,
>
> I hit the following report while testing current upstream kernel:
>
> KASAN: slab-use-after-free in dummy_timer
>
> on commit: fce2dfa773ced15f27dd27cd0b482a7473cdcf2a (2026-07-16)
>
> The reproducer and .config files are here.
> https://gist.github.com/shuangpengbai/a410bc05b4f22d1ba4ce7ef059043fea
>
> I'm happy to test debug patches or provide additional information.
>
> Reported-by: Shuangpeng Bai <shuangpeng.kernel@gmail.com>
>
> [ 400.891255][ C0] BUG: KASAN: slab-use-after-free in dummy_timer (drivers/usb/common/usb-otg-fsm.c:393)
> [ 400.891273][ C0] Read of size 4 at addr ffff8881789bc20c by task kworker/0:2/773
> [ 400.891276][ C0]
> [ 400.891291][ C0] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
> [ 400.891294][ C0] Workqueue: usb_hub_wq hub_event
> [ 400.891299][ C0] Call Trace:
> [ 400.891301][ C0] <IRQ>
> [ 400.891302][ C0] dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120)
> [ 400.891306][ C0] print_report (mm/kasan/report.c:378 mm/kasan/report.c:482)
> [ 400.891322][ C0] kasan_report (mm/kasan/report.c:595)
> [ 400.891330][ C0] dummy_timer (drivers/usb/common/usb-otg-fsm.c:393)
> [ 400.891397][ C0] __hrtimer_run_queues (kernel/time/hrtimer.c:2032 kernel/time/hrtimer.c:2096)
> [ 400.891403][ C0] hrtimer_run_softirq (kernel/time/hrtimer.c:2113)
> [ 400.891414][ C0] handle_softirqs (kernel/softirq.c:622)
> [ 400.891420][ C0] __irq_exit_rcu (kernel/softirq.c:656 kernel/softirq.c:496 kernel/softirq.c:735)
> [ 400.891423][ C0] sysvec_apic_timer_interrupt (arch/x86/kernel/apic/apic.c:1062 arch/x86/kernel/apic/apic.c:1062)
> [ 400.891427][ C0] </IRQ>
> [ 400.891428][ C0] <TASK>
> [ 400.891579][ C0] really_probe (drivers/base/dd.c:644 drivers/base/dd.c:706)
> [ 400.891582][ C0] __driver_probe_device (drivers/base/dd.c:868)
> [ 400.891585][ C0] driver_probe_device (drivers/base/dd.c:898)
> [ 400.891588][ C0] __device_attach_driver (drivers/base/dd.c:1026)
> [ 400.891593][ C0] bus_for_each_drv (drivers/base/bus.c:500)
> [ 400.891615][ C0] __device_attach (drivers/base/dd.c:1098)
> [ 400.891631][ C0] device_initial_probe (drivers/base/dd.c:1153)
> [ 400.891634][ C0] bus_probe_device (drivers/base/bus.c:620)
> [ 400.891637][ C0] device_add (drivers/base/core.c:3772)
> [ 400.891641][ C0] usb_set_configuration (drivers/usb/core/message.c:2268)
> [ 400.891647][ C0] usb_generic_driver_probe (drivers/usb/core/generic.c:250)
> [ 400.891651][ C0] usb_probe_device (drivers/usb/core/driver.c:291)
> [ 400.891653][ C0] really_probe (drivers/base/dd.c:? drivers/base/dd.c:706)
> [ 400.891656][ C0] __driver_probe_device (drivers/base/dd.c:868)
> [ 400.891663][ C0] driver_probe_device (drivers/base/dd.c:898)
> [ 400.891665][ C0] __device_attach_driver (drivers/base/dd.c:1026)
> [ 400.891671][ C0] bus_for_each_drv (drivers/base/bus.c:500)
> [ 400.891685][ C0] __device_attach (drivers/base/dd.c:1098)
> [ 400.891704][ C0] device_initial_probe (drivers/base/dd.c:1153)
> [ 400.891707][ C0] bus_probe_device (drivers/base/bus.c:620)
> [ 400.891710][ C0] device_add (drivers/base/core.c:3772)
> [ 400.891714][ C0] usb_new_device (drivers/usb/core/hub.c:2695)
> [ 400.891726][ C0] hub_event (drivers/usb/core/hub.c:5567 drivers/usb/core/hub.c:5707 drivers/usb/core/hub.c:5871 drivers/usb/core/hub.c:5953)
> [ 400.891743][ C0] process_scheduled_works (kernel/workqueue.c:3322 kernel/workqueue.c:3405)
> [ 400.891748][ C0] worker_thread (kernel/workqueue.c:3486)
> [ 400.891756][ C0] kthread (kernel/kthread.c:436)
> [ 400.891764][ C0] ret_from_fork (arch/x86/kernel/process.c:158)
> [ 400.891790][ C0] ret_from_fork_asm (arch/x86/entry/entry_64.S:245)
> [ 400.891795][ C0] </TASK>
> [ 400.891797][ C0] Freed by task 773 on cpu 0 at 400.890164s:
> [ 400.891805][ C0] kasan_save_track (mm/kasan/common.c:57 mm/kasan/common.c:78)
> [ 400.891813][ C0] kasan_save_free_info (mm/kasan/generic.c:584)
> [ 400.891821][ C0] __kasan_slab_free (mm/kasan/common.c:253 mm/kasan/common.c:285)
> [ 400.891824][ C0] kfree (./include/linux/kasan.h:235 mm/slub.c:2705 mm/slub.c:6405 mm/slub.c:6720)
> [ 400.891827][ C0] usb6fire_comm_destroy (sound/usb/6fire/comm.c:197)
> [ 400.891830][ C0] usb6fire_card_free (sound/usb/6fire/chip.c:65)
> [ 400.891832][ C0] release_card_device (sound/core/init.c:594 sound/core/init.c:153)
> [ 400.891852][ C0] kobject_put (lib/kobject.c:689 lib/kobject.c:720 ./include/linux/kref.h:65 lib/kobject.c:737)
> [ 400.891855][ C0] snd_card_free (sound/core/init.c:626 sound/core/init.c:658)
> [ 400.891858][ C0] usb6fire_chip_probe (sound/usb/6fire/chip.c:153)
> [ 400.891860][ C0] usb_probe_interface (drivers/usb/core/driver.c:396)
Through a quick glance, this looks like a stale URB firing after the
release. Does the patch below work?
thanks,
Takashi
-- 8< --
--- a/sound/usb/6fire/chip.c
+++ b/sound/usb/6fire/chip.c
@@ -150,6 +150,10 @@ static int usb6fire_chip_probe(struct usb_interface *intf,
return 0;
destroy_chip:
+ chip->shutdown = true;
+ if (card)
+ snd_card_disconnect(card);
+ usb6fire_chip_abort(chip);
snd_card_free(card);
return ret;
}
^ permalink raw reply [flat|nested] 2+ messages in thread
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2026-07-24 3:07 [BUG] ALSA: usb: 6fire: KASAN slab-use-after-free in dummy_timer Shuangpeng Bai
2026-07-24 7:45 ` Takashi Iwai
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