[moderation] [media?] KASAN: slab-use-after-free Read in em28xx_unregister_media_device

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5ac87cd859ec Merge 6.19-rc6 usb-next
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing
console output: https://syzkaller.appspot.com/x/log.txt?x=140e73fa580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a04e768f944f1aa0
dashboard link: https://syzkaller.appspot.com/bug?extid=96b501bb9cdb85346ec7
compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
CC: [laurent....@ideasonboard.com linux-...@vger.kernel.org linux...@vger.kernel.org linu...@vger.kernel.org mch...@kernel.org sakari...@linux.intel.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b927a84e0088/disk-5ac87cd8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b8131bd9dbee/vmlinux-5ac87cd8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/24fc40a81925/bzImage-5ac87cd8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+96b501...@syzkaller.appspotmail.com

em28xx 8-1:0.132: Closing input extension
==================================================================
BUG: KASAN: slab-use-after-free in media_device_unregister drivers/media/mc/mc-device.c:804 [inline]
BUG: KASAN: slab-use-after-free in media_device_unregister+0x565/0x5e0 drivers/media/mc/mc-device.c:782
Read of size 8 at addr ffff88813572c210 by task kworker/1:6/5730

CPU: 1 UID: 0 PID: 5730 Comm: kworker/1:6 Not tainted syzkaller #0 PREEMPT(voluntary)
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 lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x156/0x4c9 mm/kasan/report.c:482
kasan_report+0xdf/0x1a0 mm/kasan/report.c:595
media_device_unregister drivers/media/mc/mc-device.c:804 [inline]
media_device_unregister+0x565/0x5e0 drivers/media/mc/mc-device.c:782
em28xx_unregister_media_device+0x4e/0xe0 drivers/media/usb/em28xx/em28xx-cards.c:3511
em28xx_release_resources+0x79/0x1b0 drivers/media/usb/em28xx/em28xx-cards.c:3532
em28xx_usb_disconnect.cold+0x17d/0x253 drivers/media/usb/em28xx/em28xx-cards.c:4201
usb_unbind_interface+0x1dd/0x9e0 drivers/usb/core/driver.c:458
device_remove drivers/base/dd.c:571 [inline]
device_remove+0x12a/0x180 drivers/base/dd.c:563
__device_release_driver drivers/base/dd.c:1282 [inline]
device_release_driver_internal+0x42e/0x600 drivers/base/dd.c:1305
bus_remove_device+0x22f/0x440 drivers/base/bus.c:616
device_del+0x376/0x9b0 drivers/base/core.c:3878
usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1418
usb_disconnect+0x2e2/0x9a0 drivers/usb/core/hub.c:2345
hub_port_connect drivers/usb/core/hub.c:5407 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
port_event drivers/usb/core/hub.c:5871 [inline]
hub_event+0x1d0c/0x4af0 drivers/usb/core/hub.c:5953
process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
process_scheduled_works kernel/workqueue.c:3340 [inline]
worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
kthread+0x3b3/0x730 kernel/kthread.c:463
ret_from_fork+0x6c3/0xa20 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
</TASK>

Allocated by task 11958:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:415
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
em28xx_v4l2_init.cold+0x94/0x3503 drivers/media/usb/em28xx/em28xx-video.c:2532
em28xx_init_extension+0x13a/0x200 drivers/media/usb/em28xx/em28xx-core.c:1117
request_module_async+0x61/0x80 drivers/media/usb/em28xx/em28xx-cards.c:3457
process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
process_scheduled_works kernel/workqueue.c:3340 [inline]
worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
kthread+0x3b3/0x730 kernel/kthread.c:463
ret_from_fork+0x6c3/0xa20 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

Freed by task 11958:
kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
kasan_save_track+0x14/0x30 mm/kasan/common.c:78
kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
poison_slab_object mm/kasan/common.c:253 [inline]
__kasan_slab_free+0x43/0x70 mm/kasan/common.c:285
kasan_slab_free include/linux/kasan.h:235 [inline]
slab_free_hook mm/slub.c:2540 [inline]
slab_free mm/slub.c:6670 [inline]
kfree+0x1ad/0x630 mm/slub.c:6878
kref_put.isra.0+0x56/0x90 include/linux/kref.h:65
em28xx_v4l2_init.cold+0x280/0x3503 drivers/media/usb/em28xx/em28xx-video.c:2901
em28xx_init_extension+0x13a/0x200 drivers/media/usb/em28xx/em28xx-core.c:1117
request_module_async+0x61/0x80 drivers/media/usb/em28xx/em28xx-cards.c:3457
process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257
process_scheduled_works kernel/workqueue.c:3340 [inline]
worker_thread+0x5da/0xe40 kernel/workqueue.c:3421
kthread+0x3b3/0x730 kernel/kthread.c:463
ret_from_fork+0x6c3/0xa20 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

The buggy address belongs to the object at ffff88813572c000
which belongs to the cache kmalloc-8k of size 8192
The buggy address is located 528 bytes inside of
freed 8192-byte region [ffff88813572c000, ffff88813572e000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x135728
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x200000000000040(head|node=0|zone=2)
page_type: f5(slab)
raw: 0200000000000040 ffff888100042280 ffffea00046dc600 dead000000000002
raw: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 0200000000000040 ffff888100042280 ffffea00046dc600 dead000000000002
head: 0000000000000000 0000000080020002 00000000f5000000 0000000000000000
head: 0200000000000003 ffffea0004d5ca01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1122, tgid 1122 (kworker/1:2), ts 1154723928347, free_ts 1154474178179
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1e1/0x250 mm/page_alloc.c:1884
prep_new_page mm/page_alloc.c:1892 [inline]
get_page_from_freelist+0xd57/0x3b20 mm/page_alloc.c:3945
__alloc_frozen_pages_noprof+0x269/0x2230 mm/page_alloc.c:5240
alloc_pages_mpol+0xe8/0x410 mm/mempolicy.c:2486
alloc_slab_page mm/slub.c:3075 [inline]
allocate_slab mm/slub.c:3248 [inline]
new_slab+0x2c4/0x440 mm/slub.c:3302
___slab_alloc+0xda3/0x1ca0 mm/slub.c:4656
__slab_alloc.isra.0+0x63/0x110 mm/slub.c:4779
__slab_alloc_node mm/slub.c:4855 [inline]
slab_alloc_node mm/slub.c:5251 [inline]
__do_kmalloc_node mm/slub.c:5656 [inline]
__kmalloc_noprof+0x5c3/0x990 mm/slub.c:5669
kmalloc_noprof include/linux/slab.h:961 [inline]
hcd_buffer_alloc+0x1f5/0x290 drivers/usb/core/buffer.c:134
usb_alloc_coherent+0x5f/0xa0 drivers/usb/core/usb.c:1010
hdpvr_alloc_buffers+0x12e/0x650 drivers/media/usb/hdpvr/hdpvr-video.c:162
hdpvr_probe.cold+0x929/0x12fe drivers/media/usb/hdpvr/hdpvr-core.c:350
usb_probe_interface+0x303/0x8f0 drivers/usb/core/driver.c:396
call_driver_probe drivers/base/dd.c:581 [inline]
really_probe+0x241/0xa60 drivers/base/dd.c:659
__driver_probe_device+0x1de/0x400 drivers/base/dd.c:801
driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
page last free pid 2860 tgid 2860 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1433 [inline]
__free_frozen_pages+0x7d1/0x1010 mm/page_alloc.c:2973
discard_slab mm/slub.c:3346 [inline]
__put_partials+0x127/0x160 mm/slub.c:3886
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x47/0xe0 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x1a0/0x1f0 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x4e/0x70 mm/kasan/common.c:350
kasan_slab_alloc include/linux/kasan.h:253 [inline]
slab_post_alloc_hook mm/slub.c:4953 [inline]
slab_alloc_node mm/slub.c:5263 [inline]
kmem_cache_alloc_node_noprof+0x292/0x7d0 mm/slub.c:5315
__alloc_skb+0x156/0x410 net/core/skbuff.c:679
alloc_skb include/linux/skbuff.h:1383 [inline]
netlink_alloc_large_skb+0x69/0x150 net/netlink/af_netlink.c:1184
netlink_sendmsg+0x680/0xda0 net/netlink/af_netlink.c:1869
sock_sendmsg_nosec net/socket.c:727 [inline]
__sock_sendmsg net/socket.c:742 [inline]
____sys_sendmsg+0xa54/0xc30 net/socket.c:2592
___sys_sendmsg+0x190/0x1e0 net/socket.c:2646
__sys_sendmsg+0x170/0x220 net/socket.c:2678
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc9/0x570 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff88813572c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88813572c180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88813572c200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88813572c280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88813572c300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


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