[v6.6] KASAN: slab-use-after-free Read in em28xx_release_resources

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c596736dadab Linux 6.6.120
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13ab0522580000
kernel config: https://syzkaller.appspot.com/x/.config?x=691a6769a86ac817
dashboard link: https://syzkaller.appspot.com/bug?extid=6fbf44b3f140e9330efa
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/855c94eb3eef/disk-c596736d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b7510b30b774/vmlinux-c596736d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3ce7fe4f6991/bzImage-c596736d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6fbf44...@syzkaller.appspotmail.com

em28xx 1-1:0.132: Closing input extension
==================================================================
BUG: KASAN: slab-use-after-free in media_device_unregister+0x141/0x400 drivers/media/mc/mc-device.c:808
Read of size 8 at addr ffff88807cb64210 by task kworker/0:0/8

CPU: 0 PID: 8 Comm: kworker/0:0 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: usb_hub_wq hub_event
Call Trace:
<TASK>
dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xac/0x220 mm/kasan/report.c:468
kasan_report+0x117/0x150 mm/kasan/report.c:581
media_device_unregister+0x141/0x400 drivers/media/mc/mc-device.c:808
em28xx_unregister_media_device drivers/media/usb/em28xx/em28xx-cards.c:3459 [inline]
em28xx_release_resources+0xac/0x240 drivers/media/usb/em28xx/em28xx-cards.c:3480
em28xx_usb_disconnect+0x19a/0x2f0 drivers/media/usb/em28xx/em28xx-cards.c:4149
usb_unbind_interface+0x1f2/0x870 drivers/usb/core/driver.c:458
device_remove drivers/base/dd.c:569 [inline]
__device_release_driver drivers/base/dd.c:1272 [inline]
device_release_driver_internal+0x4cb/0x7a0 drivers/base/dd.c:1295
bus_remove_device+0x342/0x400 drivers/base/bus.c:576
device_del+0x50b/0x900 drivers/base/core.c:3872
usb_disable_device+0x3e9/0x8a0 drivers/usb/core/message.c:1416
usb_disconnect+0x34c/0x8a0 drivers/usb/core/hub.c:2315
hub_port_connect drivers/usb/core/hub.c:5369 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5669 [inline]
port_event drivers/usb/core/hub.c:5833 [inline]
hub_event+0x1cef/0x49c0 drivers/usb/core/hub.c:5915
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
</TASK>

Allocated by task 5767:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
____kasan_kmalloc mm/kasan/common.c:375 [inline]
__kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:721 [inline]
em28xx_v4l2_init+0x10b/0x2e70 drivers/media/usb/em28xx/em28xx-video.c:2532
em28xx_init_extension+0x11c/0x1b0 drivers/media/usb/em28xx/em28xx-core.c:1116
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

Freed by task 5767:
kasan_save_stack mm/kasan/common.c:46 [inline]
kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1811 [inline]
slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1837
slab_free mm/slub.c:3830 [inline]
__kmem_cache_free+0xba/0x1f0 mm/slub.c:3843
em28xx_free_v4l2 drivers/media/usb/em28xx/em28xx-video.c:2118 [inline]
kref_put include/linux/kref.h:65 [inline]
em28xx_v4l2_init+0x1670/0x2e70 drivers/media/usb/em28xx/em28xx-video.c:2901
em28xx_init_extension+0x11c/0x1b0 drivers/media/usb/em28xx/em28xx-core.c:1116
process_one_work kernel/workqueue.c:2634 [inline]
process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
kthread+0x2fa/0x390 kernel/kthread.c:388
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

The buggy address belongs to the object at ffff88807cb64000
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 528 bytes inside of
freed 8192-byte region [ffff88807cb64000, ffff88807cb66000)

The buggy address belongs to the physical page:
page:ffffea0001f2d800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x7cb60
head:ffffea0001f2d800 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017842280 ffffea00017d3e00 dead000000000002
raw: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5422, tgid 5422 (S40network), ts 36818795773, free_ts 36789466190
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
prep_new_page mm/page_alloc.c:1561 [inline]
get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
__alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
alloc_slab_page+0x5d/0x170 mm/slub.c:1881
allocate_slab mm/slub.c:2028 [inline]
new_slab+0x87/0x2e0 mm/slub.c:2081
___slab_alloc+0xc6d/0x1300 mm/slub.c:3253
__slab_alloc mm/slub.c:3339 [inline]
__slab_alloc_node mm/slub.c:3392 [inline]
slab_alloc_node mm/slub.c:3485 [inline]
__kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3534
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:721 [inline]
tomoyo_print_bprm security/tomoyo/audit.c:26 [inline]
tomoyo_init_log+0x1104/0x1f10 security/tomoyo/audit.c:264
tomoyo_supervisor+0x32d/0x1080 security/tomoyo/common.c:2089
tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
tomoyo_env_perm+0x14a/0x1e0 security/tomoyo/environ.c:63
tomoyo_environ security/tomoyo/domain.c:672 [inline]
tomoyo_find_next_domain+0x1594/0x1a60 security/tomoyo/domain.c:881
tomoyo_bprm_check_security+0x116/0x170 security/tomoyo/tomoyo.c:101
security_bprm_check+0x62/0xa0 security/security.c:1103
search_binary_handler fs/exec.c:1763 [inline]
exec_binprm fs/exec.c:1817 [inline]
bprm_execve+0xa51/0x16f0 fs/exec.c:1892
do_execveat_common+0x51b/0x6c0 fs/exec.c:1998
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1154 [inline]
free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
discard_slab mm/slub.c:2127 [inline]
__unfreeze_partials+0x1cf/0x210 mm/slub.c:2667
put_cpu_partial+0x17c/0x250 mm/slub.c:2743
__slab_free+0x31d/0x410 mm/slub.c:3700
qlink_free mm/kasan/quarantine.c:166 [inline]
qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
__kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:306
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
slab_alloc_node mm/slub.c:3495 [inline]
__kmem_cache_alloc_node+0x13e/0x260 mm/slub.c:3534
kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
kmalloc include/linux/slab.h:600 [inline]
kzalloc include/linux/slab.h:721 [inline]
tomoyo_print_bprm security/tomoyo/audit.c:26 [inline]
tomoyo_init_log+0x1104/0x1f10 security/tomoyo/audit.c:264
tomoyo_supervisor+0x32d/0x1080 security/tomoyo/common.c:2089
tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
tomoyo_env_perm+0x14a/0x1e0 security/tomoyo/environ.c:63
tomoyo_environ security/tomoyo/domain.c:672 [inline]
tomoyo_find_next_domain+0x1594/0x1a60 security/tomoyo/domain.c:881
tomoyo_bprm_check_security+0x116/0x170 security/tomoyo/tomoyo.c:101

Memory state around the buggy address:
ffff88807cb64100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807cb64180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88807cb64200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88807cb64280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88807cb64300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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