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Message-ID: <68d7b657.a70a0220.10c4b.000e.GAE@google.com>
Date: Sat, 27 Sep 2025 03:03:03 -0700
From: syzbot <syzbot+f02665daa2abeef4a947@...kaller.appspotmail.com>
To: aha310510@...il.com, clemens@...isch.de, hdanton@...a.com, 
	linux-kernel@...r.kernel.org, linux-sound@...r.kernel.org, perex@...ex.cz, 
	syzkaller-bugs@...glegroups.com, tiwai@...e.de
Subject: Re: [syzbot] [sound?] [usb?] general protection fault in snd_usbmidi_do_output

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Write in snd_usbmidi_in_urb_complete

==================================================================
BUG: KASAN: slab-use-after-free in snd_usbmidi_in_urb_complete+0x389/0x3c0 sound/usb/midi.c:251
Write of size 1 at addr ffff888074717943 by task kworker/1:3/5866

CPU: 1 UID: 0 PID: 5866 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: usb_hub_wq hub_event
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 snd_usbmidi_in_urb_complete+0x389/0x3c0 sound/usb/midi.c:251
 __usb_hcd_giveback_urb+0x38b/0x610 drivers/usb/core/hcd.c:1661
 usb_hcd_giveback_urb+0x39b/0x450 drivers/usb/core/hcd.c:1745
 dummy_timer+0x1814/0x3a30 drivers/usb/gadget/udc/dummy_hcd.c:1995
 __run_hrtimer kernel/time/hrtimer.c:1761 [inline]
 __hrtimer_run_queues+0x202/0xad0 kernel/time/hrtimer.c:1825
 hrtimer_run_softirq+0x17d/0x350 kernel/time/hrtimer.c:1842
 handle_softirqs+0x219/0x8e0 kernel/softirq.c:579
 __do_softirq kernel/softirq.c:613 [inline]
 invoke_softirq kernel/softirq.c:453 [inline]
 __irq_exit_rcu+0x109/0x170 kernel/softirq.c:680
 irq_exit_rcu+0x9/0x30 kernel/softirq.c:696
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline]
 sysvec_apic_timer_interrupt+0xa4/0xc0 arch/x86/kernel/apic/apic.c:1050
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x62/0x350 kernel/locking/lockdep.c:5872
Code: f9 3e 12 83 f8 07 0f 87 bc 02 00 00 89 c0 48 0f a3 05 c2 d8 13 0f 0f 82 74 02 00 00 8b 35 5a 0a 14 0f 85 f6 0f 85 8d 00 00 00 <48> 8b 44 24 30 65 48 2b 05 19 f9 3e 12 0f 85 c7 02 00 00 48 83 c4
RSP: 0018:ffffc9000213f6a8 EFLAGS: 00000206
RAX: 0000000000000046 RBX: ffffffff8e5c16a0 RCX: 000000004089a3e6
RDX: 0000000000000000 RSI: ffffffff8de2c268 RDI: ffffffff8c163a00
RBP: 0000000000000002 R08: b04c8ca6f5f73b8b R09: 0000000000000000
R10: 0000000000000004 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 rcu_read_lock include/linux/rcupdate.h:841 [inline]
 class_rcu_constructor include/linux/rcupdate.h:1155 [inline]
 kernfs_root+0x34/0x2a0 fs/kernfs/kernfs-internal.h:75
 __kernfs_remove+0x302/0x8a0 fs/kernfs/dir.c:1519
 kernfs_remove_by_name_ns+0x68/0x110 fs/kernfs/dir.c:1717
 kernfs_remove_by_name include/linux/kernfs.h:633 [inline]
 remove_files+0x96/0x1c0 fs/sysfs/group.c:28
 sysfs_remove_group+0x8b/0x180 fs/sysfs/group.c:322
 sysfs_remove_groups fs/sysfs/group.c:346 [inline]
 sysfs_remove_groups+0x60/0xa0 fs/sysfs/group.c:338
 device_remove_groups drivers/base/core.c:2843 [inline]
 device_remove_attrs+0x192/0x290 drivers/base/core.c:2973
 device_del+0x38e/0x9f0 drivers/base/core.c:3877
 usb_disconnect+0x5bf/0x9c0 drivers/usb/core/hub.c:2375
 hub_port_connect drivers/usb/core/hub.c:5406 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
 port_event drivers/usb/core/hub.c:5870 [inline]
 hub_event+0x1c81/0x4fe0 drivers/usb/core/hub.c:5952
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 9:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 poison_kmalloc_redzone mm/kasan/common.c:388 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:405
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 snd_usbmidi_in_endpoint_create+0x8c/0xa70 sound/usb/midi.c:1342
 snd_usbmidi_create_endpoints_midiman+0x4c4/0xaf0 sound/usb/midi.c:2364
 __snd_usbmidi_create+0x14a4/0x1e90 sound/usb/midi.c:2647
 snd_usb_midi_v2_create+0x1ad/0x42d0 sound/usb/midi2.c:1178
 snd_usb_create_quirk+0xad/0x140 sound/usb/quirks.c:541
 usb_audio_probe+0x7f7/0x3cf0 sound/usb/card.c:976
 usb_probe_interface+0x303/0xa40 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:581 [inline]
 really_probe+0x241/0xa90 drivers/base/dd.c:659
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
 __device_attach_driver+0x1df/0x310 drivers/base/dd.c:959
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:462
 __device_attach+0x1e4/0x4b0 drivers/base/dd.c:1031
 bus_probe_device+0x17f/0x1c0 drivers/base/bus.c:537
 device_add+0x1148/0x1aa0 drivers/base/core.c:3689
 usb_set_configuration+0x1187/0x1e20 drivers/usb/core/message.c:2210
 usb_generic_driver_probe+0xb1/0x110 drivers/usb/core/generic.c:250
 usb_probe_device+0xef/0x3e0 drivers/usb/core/driver.c:291
 call_driver_probe drivers/base/dd.c:581 [inline]
 really_probe+0x241/0xa90 drivers/base/dd.c:659
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
 __device_attach_driver+0x1df/0x310 drivers/base/dd.c:959
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:462
 __device_attach+0x1e4/0x4b0 drivers/base/dd.c:1031
 bus_probe_device+0x17f/0x1c0 drivers/base/bus.c:537
 device_add+0x1148/0x1aa0 drivers/base/core.c:3689
 usb_new_device+0xd07/0x1a60 drivers/usb/core/hub.c:2694
 hub_port_connect drivers/usb/core/hub.c:5566 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
 port_event drivers/usb/core/hub.c:5870 [inline]
 hub_event+0x2f34/0x4fe0 drivers/usb/core/hub.c:5952
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 9:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:47
 kasan_save_track+0x14/0x30 mm/kasan/common.c:68
 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:576
 poison_slab_object mm/kasan/common.c:243 [inline]
 __kasan_slab_free+0x60/0x70 mm/kasan/common.c:275
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2422 [inline]
 slab_free mm/slub.c:4695 [inline]
 kfree+0x2b4/0x4d0 mm/slub.c:4894
 snd_usbmidi_free sound/usb/midi.c:1532 [inline]
 snd_usbmidi_rawmidi_free+0xbd/0x130 sound/usb/midi.c:1592
 snd_rawmidi_free.part.0+0x398/0x560 sound/core/rawmidi.c:1934
 snd_rawmidi_free sound/core/rawmidi.c:1923 [inline]
 snd_rawmidi_dev_free+0x3e/0x60 sound/core/rawmidi.c:1945
 __snd_device_free+0x1a7/0x410 sound/core/device.c:76
 snd_device_free_all+0xf3/0x220 sound/core/device.c:233
 snd_card_do_free sound/core/init.c:587 [inline]
 release_card_device+0x77/0x1d0 sound/core/init.c:153
 device_release+0xa4/0x240 drivers/base/core.c:2565
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x1e7/0x5a0 lib/kobject.c:737
 put_device+0x1f/0x30 drivers/base/core.c:3797
 snd_card_free_when_closed sound/core/init.c:618 [inline]
 snd_card_free_when_closed sound/core/init.c:612 [inline]
 snd_card_free+0x11a/0x190 sound/core/init.c:650
 usb_audio_probe+0x1507/0x3cf0 sound/usb/card.c:1034
 usb_probe_interface+0x303/0xa40 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:581 [inline]
 really_probe+0x241/0xa90 drivers/base/dd.c:659
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
 __device_attach_driver+0x1df/0x310 drivers/base/dd.c:959
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:462
 __device_attach+0x1e4/0x4b0 drivers/base/dd.c:1031
 bus_probe_device+0x17f/0x1c0 drivers/base/bus.c:537
 device_add+0x1148/0x1aa0 drivers/base/core.c:3689
 usb_set_configuration+0x1187/0x1e20 drivers/usb/core/message.c:2210
 usb_generic_driver_probe+0xb1/0x110 drivers/usb/core/generic.c:250
 usb_probe_device+0xef/0x3e0 drivers/usb/core/driver.c:291
 call_driver_probe drivers/base/dd.c:581 [inline]
 really_probe+0x241/0xa90 drivers/base/dd.c:659
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
 __device_attach_driver+0x1df/0x310 drivers/base/dd.c:959
 bus_for_each_drv+0x159/0x1e0 drivers/base/bus.c:462
 __device_attach+0x1e4/0x4b0 drivers/base/dd.c:1031
 bus_probe_device+0x17f/0x1c0 drivers/base/bus.c:537
 device_add+0x1148/0x1aa0 drivers/base/core.c:3689
 usb_new_device+0xd07/0x1a60 drivers/usb/core/hub.c:2694
 hub_port_connect drivers/usb/core/hub.c:5566 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5706 [inline]
 port_event drivers/usb/core/hub.c:5870 [inline]
 hub_event+0x2f34/0x4fe0 drivers/usb/core/hub.c:5952
 process_one_work+0x9cf/0x1b70 kernel/workqueue.c:3236
 process_scheduled_works kernel/workqueue.c:3319 [inline]
 worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
 kthread+0x3c5/0x780 kernel/kthread.c:463
 ret_from_fork+0x56d/0x730 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888074717800
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 323 bytes inside of
 freed 512-byte region [ffff888074717800, ffff888074717a00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x74714
head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801b841c80 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801b841c80 dead000000000100 dead000000000122
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000002 ffffea0001d1c501 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 10, tgid 10 (kworker/0:1), ts 289964868636, free_ts 191685793183
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1c0/0x230 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x132b/0x38e0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x261/0x23f0 mm/page_alloc.c:5148
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2492 [inline]
 allocate_slab mm/slub.c:2660 [inline]
 new_slab+0x247/0x330 mm/slub.c:2714
 ___slab_alloc+0xcf2/0x1750 mm/slub.c:3901
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3992
 __slab_alloc_node mm/slub.c:4067 [inline]
 slab_alloc_node mm/slub.c:4228 [inline]
 __kmalloc_cache_noprof+0xfb/0x3e0 mm/slub.c:4402
 kmalloc_noprof include/linux/slab.h:905 [inline]
 kzalloc_noprof include/linux/slab.h:1039 [inline]
 device_private_init drivers/base/core.c:3534 [inline]
 device_add+0xccc/0x1aa0 drivers/base/core.c:3585
 usb_set_configuration+0x1187/0x1e20 drivers/usb/core/message.c:2210
 usb_generic_driver_probe+0xb1/0x110 drivers/usb/core/generic.c:250
 usb_probe_device+0xef/0x3e0 drivers/usb/core/driver.c:291
 call_driver_probe drivers/base/dd.c:581 [inline]
 really_probe+0x241/0xa90 drivers/base/dd.c:659
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
 __device_attach_driver+0x1df/0x310 drivers/base/dd.c:959
page last free pid 6777 tgid 6777 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0x7d5/0x10f0 mm/page_alloc.c:2895
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x4d/0x120 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x195/0x1e0 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x69/0x90 mm/kasan/common.c:340
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4191 [inline]
 slab_alloc_node mm/slub.c:4240 [inline]
 kmem_cache_alloc_noprof+0x1cb/0x3b0 mm/slub.c:4247
 getname_flags.part.0+0x4c/0x550 fs/namei.c:146
 getname_flags+0x93/0xf0 include/linux/audit.h:322
 do_readlinkat+0xb4/0x3a0 fs/stat.c:575
 __do_sys_readlink fs/stat.c:613 [inline]
 __se_sys_readlink fs/stat.c:610 [inline]
 __x64_sys_readlink+0x78/0xc0 fs/stat.c:610
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x4e0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888074717800: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888074717880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888074717900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888074717980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888074717a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess):
   0:	f9                   	stc
   1:	3e 12 83 f8 07 0f 87 	ds adc -0x78f0f808(%rbx),%al
   8:	bc 02 00 00 89       	mov    $0x89000002,%esp
   d:	c0 48 0f a3          	rorb   $0xa3,0xf(%rax)
  11:	05 c2 d8 13 0f       	add    $0xf13d8c2,%eax
  16:	0f 82 74 02 00 00    	jb     0x290
  1c:	8b 35 5a 0a 14 0f    	mov    0xf140a5a(%rip),%esi        # 0xf140a7c
  22:	85 f6                	test   %esi,%esi
  24:	0f 85 8d 00 00 00    	jne    0xb7
* 2a:	48 8b 44 24 30       	mov    0x30(%rsp),%rax <-- trapping instruction
  2f:	65 48 2b 05 19 f9 3e 	sub    %gs:0x123ef919(%rip),%rax        # 0x123ef950
  36:	12
  37:	0f 85 c7 02 00 00    	jne    0x304
  3d:	48                   	rex.W
  3e:	83                   	.byte 0x83
  3f:	c4                   	.byte 0xc4


Tested on:

commit:         fec734e8 Merge tag 'riscv-for-linus-v6.17-rc8' of git:..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13bb3d34580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=927198eca77e75d9
dashboard link: https://syzkaller.appspot.com/bug?extid=f02665daa2abeef4a947
compiler:       gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
patch:          https://syzkaller.appspot.com/x/patch.diff?x=17773142580000


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