Re: [syzbot] [media?] [usb?] kernel BUG in v4l2_device_put

Re: [syzbot] [media?] [usb?] kernel BUG in v4l2_device_put

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+809dfc586f33fc44b6ac@syzkaller.appspotmail.com
Tested-by: syzbot+809dfc586f33fc44b6ac@syzkaller.appspotmail.com

Tested on:

commit:         8f7df005 Add linux-next specific files for 20261020
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=155a9fa9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9c1b9b13e3e4ce1a
dashboard link: https://syzkaller.appspot.com/bug?extid=809dfc586f33fc44b6ac
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=12170f99580000

Note: testing is done by a robot and is best-effort only.

Re: [syzbot] [media?] [usb?] kernel BUG in v4l2_device_put

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in em28xx_write_regs_req

==================================================================
BUG: KASAN: slab-use-after-free in __intf_to_usbdev include/linux/usb.h:752 [inline]
BUG: KASAN: slab-use-after-free in em28xx_write_regs_req+0x79/0x3c0 drivers/media/usb/em28xx/em28xx-core.c:138
Read of size 8 at addr ffff88802229e0b8 by task v4l_id/8728

CPU: 0 UID: 0 PID: 8728 Comm: v4l_id Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 __intf_to_usbdev include/linux/usb.h:752 [inline]
 em28xx_write_regs_req+0x79/0x3c0 drivers/media/usb/em28xx/em28xx-core.c:138
 em28xx_write_regs drivers/media/usb/em28xx/em28xx-core.c:179 [inline]
 em28xx_write_reg+0x89/0xd0 drivers/media/usb/em28xx/em28xx-core.c:186
 em28xx_set_outfmt+0xb1/0x420 drivers/media/usb/em28xx/em28xx-video.c:233
 em28xx_resolution_set+0x261/0x7f0 drivers/media/usb/em28xx/em28xx-video.c:339
 em28xx_v4l2_open+0x21a/0x840 drivers/media/usb/em28xx/em28xx-video.c:2390
 v4l2_open+0x1bc/0x3a0 drivers/media/v4l2-core/v4l2-dev.c:433
 chrdev_open+0x4d9/0x600 fs/char_dev.c:413
 do_dentry_open+0x80e/0x1360 fs/open.c:1000
 vfs_open_consume+0x4a/0x350 fs/open.c:1131
 do_open fs/namei.c:4845 [inline]
 path_openat+0x16fc/0x20f0 fs/namei.c:5010
 do_file_open+0x23e/0x4a0 fs/namei.c:5039
 do_sys_openat2+0x115/0x200 fs/open.c:1442
 do_sys_open fs/open.c:1448 [inline]
 __do_sys_openat fs/open.c:1788 [inline]
 __se_sys_openat fs/open.c:1783 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1783
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc4a0ea7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffee11a62b0 EFLAGS: 00000202 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fc4a1572880 RCX: 00007fc4a0ea7407
RDX: 0000000000000000 RSI: 00007ffee11a7f1d RDI: ffffffffffffff9c
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 00007ffee11a6500 R14: 00007fc4a1677000 R15: 000055b0a97fd4d8
 </TASK>

Allocated by task 3215:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:409 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:426
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x600 mm/slub.c:5680
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 usb_set_configuration+0x3c5/0x2260 drivers/usb/core/message.c:2103
 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250
 usb_probe_device+0x1c3/0x3b0 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:707
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:869
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:899
 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1027
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:503
 __device_attach+0x2bd/0x430 drivers/base/dd.c:1131
 device_initial_probe+0x9c/0x100 drivers/base/dd.c:1190
 __bus_probe_device+0x126/0x220 drivers/base/bus.c:617
 device_add+0x7d7/0xb80 drivers/base/core.c:3776
 usb_new_device+0x9aa/0x1690 drivers/usb/core/hub.c:2713
 hub_port_connect drivers/usb/core/hub.c:5585 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5725 [inline]
 port_event drivers/usb/core/hub.c:5889 [inline]
 hub_event+0x28e8/0x4d30 drivers/usb/core/hub.c:5971
 process_one_work kernel/workqueue.c:3495 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 3215:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:264 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:296
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2780 [inline]
 slab_free mm/slub.c:6630 [inline]
 kfree+0x1c5/0x650 mm/slub.c:6923
 device_release+0xc4/0x1f0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x222/0x550 lib/kobject.c:737
 usb_disable_device+0x611/0x8d0 drivers/usb/core/message.c:1491
 usb_disconnect+0x346/0x9a0 drivers/usb/core/hub.c:2355
 hub_port_connect drivers/usb/core/hub.c:5425 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5725 [inline]
 port_event drivers/usb/core/hub.c:5889 [inline]
 hub_event+0x1bbb/0x4d30 drivers/usb/core/hub.c:5971
 process_one_work kernel/workqueue.c:3495 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff88802229e000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 184 bytes inside of
 freed 2048-byte region [ffff88802229e000, ffff88802229e800)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x22298
head: order:3 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 ffff88813ff30000 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813ff30000 dead000000000100 dead000000000122
head: 0000000000000000 0000000000080008 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 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 1, tgid 1 (swapper/0), ts 5001221219
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1856
 prep_new_page mm/page_alloc.c:1864 [inline]
 get_page_from_freelist+0x220f/0x2280 mm/page_alloc.c:3935
 __alloc_frozen_pages_noprof+0x1fe/0x410 mm/page_alloc.c:5459
 alloc_slab_page mm/slub.c:3384 [inline]
 allocate_slab+0x7d/0x5e0 mm/slub.c:3499
 new_slab mm/slub.c:3550 [inline]
 refill_objects+0x2d5/0x350 mm/slub.c:7539
 refill_sheaf mm/slub.c:2917 [inline]
 __pcs_replace_empty_main+0x2c8/0x6c0 mm/slub.c:4811
 alloc_from_pcs mm/slub.c:4887 [inline]
 slab_alloc_node mm/slub.c:5021 [inline]
 __kmalloc_cache_noprof+0x396/0x600 mm/slub.c:5676
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 acpi_add_single_object+0xdb/0x1b30 drivers/acpi/scan.c:1870
 acpi_bus_check_add+0x2b5/0x840 drivers/acpi/scan.c:2175
 acpi_ns_walk_namespace+0x273/0x700 drivers/acpi/acpica/nswalk.c:-1
 acpi_walk_namespace+0x125/0x190 drivers/acpi/acpica/nsxfeval.c:606
 acpi_bus_scan+0xe9/0x4b0 drivers/acpi/scan.c:2732
 acpi_scan_init+0x1bd/0x4e0 drivers/acpi/scan.c:2873
 acpi_init+0x130/0x1f0 drivers/acpi/bus.c:1483
 do_one_initcall+0x250/0x870 init/main.c:1419
 do_initcall_level+0x10a/0x1a0 init/main.c:1481
page last free pid 1 tgid 1 ts 3782412345 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1403 [inline]
 __free_pages_ok+0xb6d/0xc60 mm/page_alloc.c:1581
 btf_add_type kernel/bpf/btf.c:1782 [inline]
 btf_check_all_metas+0x5e7/0xa30 kernel/bpf/btf.c:5888
 btf_parse_base kernel/bpf/btf.c:6883 [inline]
 btf_parse_vmlinux+0x51d/0x8c0 kernel/bpf/btf.c:6917
 bpf_get_btf_vmlinux+0x48/0x70 kernel/bpf/verifier.c:23010
 btf_get_module_btf kernel/bpf/btf.c:9601 [inline]
 __register_btf_kfunc_id_set+0x62/0x14c0 kernel/bpf/btf.c:10122
 wakeup_sources_bpf_init+0x11/0x60 drivers/base/power/wakeup.c:1229
 wakeup_sources_init+0x28/0x30 drivers/base/power/wakeup.c:1240
 do_one_initcall+0x250/0x870 init/main.c:1419
 do_initcall_level+0x10a/0x1a0 init/main.c:1481
 do_initcalls+0x59/0xa0 init/main.c:1497
 kernel_init_freeable+0x29d/0x3e0 init/main.c:1732
 kernel_init+0x22/0x1d0 init/main.c:1622
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Memory state around the buggy address:
 ffff88802229df80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802229e000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88802229e080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff88802229e100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802229e180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit:         8f7df005 Add linux-next specific files for 20261020
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=16626e7f980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9c1b9b13e3e4ce1a
dashboard link: https://syzkaller.appspot.com/bug?extid=809dfc586f33fc44b6ac
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1232a3cd580000

Re: [syzbot] [media?] [usb?] kernel BUG in v4l2_device_put

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in v4l2_release

==================================================================
BUG: KASAN: slab-use-after-free in v4l2_device_supports_requests include/media/v4l2-device.h:252 [inline]
BUG: KASAN: slab-use-after-free in v4l2_release+0xfe/0x350 drivers/media/v4l2-core/v4l2-dev.c:466
Read of size 8 at addr ffff888035785b10 by task v4l_id/7282

CPU: 1 UID: 0 PID: 7282 Comm: v4l_id Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 v4l2_device_supports_requests include/media/v4l2-device.h:252 [inline]
 v4l2_release+0xfe/0x350 drivers/media/v4l2-core/v4l2-dev.c:466
 __fput+0x408/0xa40 fs/file_table.c:513
 fput_close_sync+0x11f/0x240 fs/file_table.c:619
 filp_close_sync fs/open.c:1897 [inline]
 __do_sys_close fs/open.c:2153 [inline]
 __se_sys_close+0xa2/0x160 fs/open.c:2140
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f4a56ca7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffcfee18b00 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007f4a57357880 RCX: 00007f4a56ca7407
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f4a573576e8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000013
R13: 00007ffcfee18d30 R14: 00007f4a5745c000 R15: 0000557c8543f4d8
 </TASK>

Allocated by task 5749:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:409 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:426
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x600 mm/slub.c:5680
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 em28xx_media_device_init drivers/media/usb/em28xx/em28xx-cards.c:3757 [inline]
 em28xx_init_dev+0x857/0x2680 drivers/media/usb/em28xx/em28xx-cards.c:3947
 em28xx_usb_probe+0x17b2/0x2dd0 drivers/media/usb/em28xx/em28xx-cards.c:4324
 usb_probe_interface+0x751/0xe00 drivers/usb/core/driver.c:399
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:707
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:869
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:899
 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1027
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:503
 __device_attach+0x2bd/0x430 drivers/base/dd.c:1131
 device_initial_probe+0x9c/0x100 drivers/base/dd.c:1190
 __bus_probe_device+0x126/0x220 drivers/base/bus.c:617
 device_add+0x7d7/0xb80 drivers/base/core.c:3776
 usb_set_configuration+0x1bb5/0x2260 drivers/usb/core/message.c:2280
 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250
 usb_probe_device+0x1c3/0x3b0 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:707
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:869
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:899
 __device_attach_driver+0x270/0x410 drivers/base/dd.c:1027
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:503
 __device_attach+0x2bd/0x430 drivers/base/dd.c:1131
 device_initial_probe+0x9c/0x100 drivers/base/dd.c:1190
 __bus_probe_device+0x126/0x220 drivers/base/bus.c:617
 device_add+0x7d7/0xb80 drivers/base/core.c:3776
 usb_new_device+0x9aa/0x1690 drivers/usb/core/hub.c:2713
 hub_port_connect drivers/usb/core/hub.c:5585 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5725 [inline]
 port_event drivers/usb/core/hub.c:5889 [inline]
 hub_event+0x28e8/0x4d30 drivers/usb/core/hub.c:5971
 process_one_work kernel/workqueue.c:3495 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 5749:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:264 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:296
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2780 [inline]
 slab_free mm/slub.c:6630 [inline]
 kfree+0x1c5/0x650 mm/slub.c:6923
 em28xx_unregister_media_device drivers/media/usb/em28xx/em28xx-cards.c:3779 [inline]
 em28xx_release_resources+0xde/0x240 drivers/media/usb/em28xx/em28xx-cards.c:3798
 em28xx_usb_disconnect+0x19f/0x2f0 drivers/media/usb/em28xx/em28xx-cards.c:4493
 usb_unbind_interface+0x295/0x9c0 drivers/usb/core/driver.c:460
 device_remove drivers/base/dd.c:619 [inline]
 __device_release_driver drivers/base/dd.c:1357 [inline]
 device_release_driver_internal+0x48d/0x7d0 drivers/base/dd.c:1380
 bus_remove_device+0x444/0x560 drivers/base/bus.c:681
 device_del+0x524/0x8f0 drivers/base/core.c:3965
 usb_disable_device+0x3d4/0x8d0 drivers/usb/core/message.c:1484
 usb_disconnect+0x346/0x9a0 drivers/usb/core/hub.c:2355
 hub_port_connect drivers/usb/core/hub.c:5425 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5725 [inline]
 port_event drivers/usb/core/hub.c:5889 [inline]
 hub_event+0x1bbb/0x4d30 drivers/usb/core/hub.c:5971
 process_one_work kernel/workqueue.c:3495 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff888035785800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 784 bytes inside of
 freed 1024-byte region [ffff888035785800, ffff888035785c00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x35780
head: order:3 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 ffff88813ff2bdc0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813ff2bdc0 dead000000000100 dead000000000122
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000003 fffffffffffffe01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 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 0xd2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 162, tgid 162 (kworker/u8:7), ts 176383093465
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f9/0x250 mm/page_alloc.c:1856
 prep_new_page mm/page_alloc.c:1864 [inline]
 get_page_from_freelist+0x220f/0x2280 mm/page_alloc.c:3935
 __alloc_frozen_pages_noprof+0x1fe/0x410 mm/page_alloc.c:5459
 alloc_slab_page mm/slub.c:3384 [inline]
 allocate_slab+0x7d/0x5e0 mm/slub.c:3499
 new_slab mm/slub.c:3550 [inline]
 refill_objects+0x2d5/0x350 mm/slub.c:7539
 refill_sheaf mm/slub.c:2917 [inline]
 __pcs_replace_empty_main+0x2c8/0x6c0 mm/slub.c:4811
 alloc_from_pcs mm/slub.c:4887 [inline]
 slab_alloc_node mm/slub.c:5021 [inline]
 __do_kmalloc_node mm/slub.c:5530 [inline]
 __kmalloc_noprof+0x476/0x710 mm/slub.c:5556
 _kmalloc_noprof include/linux/slab.h:995 [inline]
 _kzalloc_noprof include/linux/slab.h:1312 [inline]
 ieee802_11_parse_elems_full+0x14b/0x2a10 net/mac80211/parse.c:1077
 ieee802_11_parse_elems net/mac80211/ieee80211_i.h:2583 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1542 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x509/0x2c40 net/mac80211/ibss.c:1573
 ieee80211_iface_process_skb net/mac80211/iface.c:1805 [inline]
 ieee80211_iface_work+0x769/0xfa0 net/mac80211/iface.c:1859
 cfg80211_wiphy_work+0x29e/0x420 net/wireless/core.c:610
 process_one_work kernel/workqueue.c:3495 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 31 tgid 31 ts 176051931514 stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 __free_pages_prepare mm/page_alloc.c:1403 [inline]
 __free_frozen_pages+0xc97/0xd90 mm/page_alloc.c:2954
 __slab_free+0x269/0x2c0 mm/slub.c:5926
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:361
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4720 [inline]
 slab_alloc_node mm/slub.c:5033 [inline]
 __kmalloc_cache_noprof+0x29a/0x600 mm/slub.c:5676
 _kmalloc_noprof include/linux/slab.h:991 [inline]
 dummy_urb_enqueue+0x7c/0x7a0 drivers/usb/gadget/udc/dummy_hcd.c:1327
 usb_hcd_submit_urb+0x328/0x1b60 drivers/usb/core/hcd.c:1543
 usb_start_wait_urb+0x13f/0x5b0 drivers/usb/core/message.c:62
 usb_internal_control_msg drivers/usb/core/message.c:117 [inline]
 usb_control_msg+0x234/0x3e0 drivers/usb/core/message.c:167
 get_bMaxPacketSize0 drivers/usb/core/hub.c:4869 [inline]
 hub_port_init+0xb0b/0x28c0 drivers/usb/core/hub.c:5065
 hub_port_connect drivers/usb/core/hub.c:5514 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5725 [inline]
 port_event drivers/usb/core/hub.c:5889 [inline]
 hub_event+0x24e8/0x4d30 drivers/usb/core/hub.c:5971
 process_one_work kernel/workqueue.c:3495 [inline]
 process_scheduled_works+0xc3d/0x1630 kernel/workqueue.c:3578
 worker_thread+0xa47/0xfb0 kernel/workqueue.c:3659
 kthread+0x38b/0x480 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158

Memory state around the buggy address:
 ffff888035785a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888035785a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888035785b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888035785b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888035785c00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


Tested on:

commit:         8f7df005 Add linux-next specific files for 20261020
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=120a9fa9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9c1b9b13e3e4ce1a
dashboard link: https://syzkaller.appspot.com/bug?extid=809dfc586f33fc44b6ac
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=17b7b50d580000

[syzbot] [media?] [usb?] kernel BUG in v4l2_device_put

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    8f7df005a756 Add linux-next specific files for 20261020
git tree:       linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=1061bb05580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=9c1b9b13e3e4ce1a
dashboard link: https://syzkaller.appspot.com/bug?extid=809dfc586f33fc44b6ac
compiler:       Debian clang version 22.1.8 (1~deb13u4), Debian LLD 22.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1104258e580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=176a5481580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/4ecf38da9706/disk-8f7df005.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/feab027e2efe/vmlinux-8f7df005.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ded91a573e5a/bzImage-8f7df005.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+809dfc586f33fc44b6ac@syzkaller.appspotmail.com

refcount_t: underflow; use-after-free.
------------[ cut here ]------------
kernel BUG at lib/refcount.c:37!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 1 UID: 0 PID: 7562 Comm: v4l_id Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:refcount_warn_saturate+0x104/0x110 lib/refcount.c:37
Code: 5d ff ff ff e8 4d c1 d1 fc 48 c7 c7 00 e3 8d 8c e8 61 69 30 fc 90 0f 0b e8 39 c1 d1 fc 48 c7 c7 80 e3 8d 8c e8 4d 69 30 fc 90 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc900065b7cc0 EFLAGS: 00010246
RAX: 0000000000000026 RBX: 0000000000000003 RCX: 86d7792bd9d84300
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff90033f40
RBP: 0000000000000000 R08: ffffffff81a6b7f0 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff237c1d8 R12: 1ffffffff1973318
R13: dffffc0000000000 R14: ffff88807cc000b0 R15: ffffffff882fcb70
FS:  00007f2b1fb76880(0000) GS:ffff8881234da000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055aef7b1964d CR3: 0000000075e40000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __refcount_sub_and_test include/linux/refcount.h:400 [inline]
 __refcount_dec_and_test include/linux/refcount.h:432 [inline]
 refcount_dec_and_test include/linux/refcount.h:450 [inline]
 kref_put include/linux/kref.h:64 [inline]
 v4l2_device_put+0xc2/0xd0 drivers/media/v4l2-core/v4l2-device.c:56
 device_release+0xc4/0x1f0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x222/0x550 lib/kobject.c:737
 video_put drivers/media/v4l2-core/v4l2-dev.c:173 [inline]
 v4l2_release+0x273/0x350 drivers/media/v4l2-core/v4l2-dev.c:480
 __fput+0x408/0xa40 fs/file_table.c:513
 fput_close_sync+0x11f/0x240 fs/file_table.c:619
 filp_close_sync fs/open.c:1897 [inline]
 __do_sys_close fs/open.c:2153 [inline]
 __se_sys_close+0xa2/0x160 fs/open.c:2140
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2b1f4a7407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007fffdbbfc440 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 00007f2b1fb76880 RCX: 00007f2b1f4a7407
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f2b1fb766e8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000013
R13: 00007fffdbbfc670 R14: 00007f2b1fcdd000 R15: 000055aef7b1d4d8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:refcount_warn_saturate+0x104/0x110 lib/refcount.c:37
Code: 5d ff ff ff e8 4d c1 d1 fc 48 c7 c7 00 e3 8d 8c e8 61 69 30 fc 90 0f 0b e8 39 c1 d1 fc 48 c7 c7 80 e3 8d 8c e8 4d 69 30 fc 90 <0f> 0b 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffc900065b7cc0 EFLAGS: 00010246
RAX: 0000000000000026 RBX: 0000000000000003 RCX: 86d7792bd9d84300
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff90033f40
RBP: 0000000000000000 R08: ffffffff81a6b7f0 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff237c1d8 R12: 1ffffffff1973318
R13: dffffc0000000000 R14: ffff88807cc000b0 R15: ffffffff882fcb70
FS:  00007f2b1fb76880(0000) GS:ffff8881234da000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055aef7b1964d CR3: 0000000075e40000 CR4: 00000000003526f0


---
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If the report is already addressed, let syzbot know by replying with:
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