==================================================================
BUG: KASAN: slab-use-after-free in dvb_device_open+0xc4/0x350 drivers/media/dvb-core/dvbdev.c:99
Read of size 8 at addr ffff88802ba7a018 by task syz.0.904/10121

CPU: 1 UID: 0 PID: 10121 Comm: syz.0.904 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 dvb_device_open+0xc4/0x350 drivers/media/dvb-core/dvbdev.c:99
 chrdev_open+0x4cd/0x5e0 fs/char_dev.c:411
 do_dentry_open+0x785/0x14e0 fs/open.c:949
 vfs_open+0x3b/0x340 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x2e08/0x3860 fs/namei.c:4830
 do_file_open+0x23e/0x4a0 fs/namei.c:4859
 do_sys_openat2+0x113/0x200 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f8ed4d5c84e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f8ed5c85b28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f8ed5c866c0 RCX: 00007f8ed4d5c84e
RDX: 0000000000000002 RSI: 00007f8ed5c85c00 RDI: ffffffffffffff9c
RBP: 00007f8ed5c85c00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd
R13: 00007f8ed5016038 R14: 00007f8ed5015fa0 R15: 00007ffcb9680798
 </TASK>

Allocated by task 5891:
 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:398 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
 kasan_kmalloc include/linux/kasan.h:263 [inline]
 __kmalloc_cache_noprof+0x31c/0x660 mm/slub.c:5339
 kmalloc_noprof include/linux/slab.h:962 [inline]
 kzalloc_noprof include/linux/slab.h:1204 [inline]
 snd_seq_oss_midi_check_new_port+0x168/0x730 sound/core/seq/oss/seq_oss_midi.c:156
 receive_announce+0x2aa/0x390 sound/core/seq/oss/seq_oss_init.c:132
 __snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:599 [inline]
 _snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:645 [inline]
 snd_seq_deliver_single_event+0x54d/0xb70 sound/core/seq/seq_clientmgr.c:660
 __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:708 [inline]
 deliver_to_subscribers sound/core/seq/seq_clientmgr.c:736 [inline]
 snd_seq_deliver_event+0x540/0xa10 sound/core/seq/seq_clientmgr.c:786
 snd_seq_kernel_client_dispatch+0x201/0x310 sound/core/seq/seq_clientmgr.c:2408
 snd_seq_system_broadcast+0x126/0x190 sound/core/seq/seq_system.c:88
 snd_seq_ioctl_create_port+0x742/0x970 sound/core/seq/seq_clientmgr.c:1314
 snd_seq_midisynth_probe+0xc1a/0x17b0 sound/core/seq/seq_midi.c:389
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x267/0xaf0 drivers/base/dd.c:661
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:803
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:833
 __device_attach_driver+0x2d4/0x4c0 drivers/base/dd.c:961
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2c5/0x450 drivers/base/dd.c:1033
 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1088
 bus_probe_device+0x12a/0x220 drivers/base/bus.c:574
 device_add+0x7b6/0xb70 drivers/base/core.c:3689
 snd_seq_device_dev_register+0x43/0xd0 sound/core/seq_device.c:192
 __snd_device_register sound/core/device.c:149 [inline]
 snd_device_register+0x12f/0x1c0 sound/core/device.c:179
 snd_rawmidi_dev_register+0x9be/0xf40 sound/core/rawmidi.c:2036
 __snd_device_register sound/core/device.c:149 [inline]
 snd_device_register_all+0xd3/0x1b0 sound/core/device.c:197
 snd_card_register+0x1d9/0x780 sound/core/init.c:893
 try_to_register_card+0x62c/0x790 sound/usb/card.c:-1
 usb_audio_probe+0x1d12/0x2330 sound/usb/card.c:1071
 usb_probe_interface+0x668/0xc90 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x267/0xaf0 drivers/base/dd.c:661
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:803
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:833
 __device_attach_driver+0x2d4/0x4c0 drivers/base/dd.c:961
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2c5/0x450 drivers/base/dd.c:1033
 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1088
 bus_probe_device+0x12a/0x220 drivers/base/bus.c:574
 device_add+0x7b6/0xb70 drivers/base/core.c:3689
 usb_set_configuration+0x1a87/0x2110 drivers/usb/core/message.c:2210
 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250
 usb_probe_device+0x1c4/0x3b0 drivers/usb/core/driver.c:291
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x267/0xaf0 drivers/base/dd.c:661
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:803
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:833
 __device_attach_driver+0x2d4/0x4c0 drivers/base/dd.c:961
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2c5/0x450 drivers/base/dd.c:1033
 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1088
 bus_probe_device+0x12a/0x220 drivers/base/bus.c:574
 device_add+0x7b6/0xb70 drivers/base/core.c:3689
 usb_new_device+0xa08/0x16f0 drivers/usb/core/hub.c:2695
 hub_port_connect drivers/usb/core/hub.c:5567 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x2a1c/0x4f30 drivers/usb/core/hub.c:5953
 process_one_work+0x949/0x1650 kernel/workqueue.c:3279
 process_scheduled_works kernel/workqueue.c:3362 [inline]
 worker_thread+0xb46/0x1140 kernel/workqueue.c:3443
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 5891:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2687 [inline]
 slab_free mm/slub.c:6124 [inline]
 kfree+0x1c1/0x630 mm/slub.c:6442
 snd_seq_oss_midi_check_exit_port+0x138/0x240 sound/core/seq/oss/seq_oss_midi.c:219
 receive_announce+0x2eb/0x390 sound/core/seq/oss/seq_oss_init.c:138
 __snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:599 [inline]
 _snd_seq_deliver_single_event sound/core/seq/seq_clientmgr.c:645 [inline]
 snd_seq_deliver_single_event+0x54d/0xb70 sound/core/seq/seq_clientmgr.c:660
 __deliver_to_subscribers sound/core/seq/seq_clientmgr.c:708 [inline]
 deliver_to_subscribers sound/core/seq/seq_clientmgr.c:736 [inline]
 snd_seq_deliver_event+0x540/0xa10 sound/core/seq/seq_clientmgr.c:786
 snd_seq_kernel_client_dispatch+0x201/0x310 sound/core/seq/seq_clientmgr.c:2408
 snd_seq_system_broadcast+0x126/0x190 sound/core/seq/seq_system.c:88
 snd_seq_ioctl_delete_port+0x171/0x270 sound/core/seq/seq_clientmgr.c:1336
 snd_seq_event_port_detach+0xfb/0x180 sound/core/seq/seq_ports.c:714
 snd_seq_midisynth_delete sound/core/seq/seq_midi.c:260 [inline]
 snd_seq_midisynth_remove+0x1de/0x570 sound/core/seq/seq_midi.c:432
 device_remove drivers/base/dd.c:571 [inline]
 __device_release_driver drivers/base/dd.c:1284 [inline]
 device_release_driver_internal+0x46f/0x860 drivers/base/dd.c:1307
 bus_remove_device+0x34d/0x440 drivers/base/bus.c:616
 device_del+0x527/0x8f0 drivers/base/core.c:3878
 snd_seq_device_dev_disconnect+0x3d/0x50 sound/core/seq_device.c:204
 __snd_device_disconnect sound/core/device.c:63 [inline]
 snd_device_disconnect_all+0xd7/0x210 sound/core/device.c:215
 snd_card_disconnect+0x3fc/0x870 sound/core/init.c:534
 snd_card_free_when_closed sound/core/init.c:617 [inline]
 snd_card_free+0x129/0x1d0 sound/core/init.c:650
 usb_audio_probe+0x1da8/0x2330 sound/usb/card.c:1080
 usb_probe_interface+0x668/0xc90 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x267/0xaf0 drivers/base/dd.c:661
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:803
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:833
 __device_attach_driver+0x2d4/0x4c0 drivers/base/dd.c:961
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2c5/0x450 drivers/base/dd.c:1033
 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1088
 bus_probe_device+0x12a/0x220 drivers/base/bus.c:574
 device_add+0x7b6/0xb70 drivers/base/core.c:3689
 usb_set_configuration+0x1a87/0x2110 drivers/usb/core/message.c:2210
 usb_generic_driver_probe+0x8d/0x150 drivers/usb/core/generic.c:250
 usb_probe_device+0x1c4/0x3b0 drivers/usb/core/driver.c:291
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x267/0xaf0 drivers/base/dd.c:661
 __driver_probe_device+0x18c/0x320 drivers/base/dd.c:803
 driver_probe_device+0x4f/0x240 drivers/base/dd.c:833
 __device_attach_driver+0x2d4/0x4c0 drivers/base/dd.c:961
 bus_for_each_drv+0x258/0x2f0 drivers/base/bus.c:500
 __device_attach+0x2c5/0x450 drivers/base/dd.c:1033
 device_initial_probe+0xa1/0xd0 drivers/base/dd.c:1088
 bus_probe_device+0x12a/0x220 drivers/base/bus.c:574
 device_add+0x7b6/0xb70 drivers/base/core.c:3689
 usb_new_device+0xa08/0x16f0 drivers/usb/core/hub.c:2695
 hub_port_connect drivers/usb/core/hub.c:5567 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x2a1c/0x4f30 drivers/usb/core/hub.c:5953
 process_one_work+0x949/0x1650 kernel/workqueue.c:3279
 process_scheduled_works kernel/workqueue.c:3362 [inline]
 worker_thread+0xb46/0x1140 kernel/workqueue.c:3443
 kthread+0x388/0x470 kernel/kthread.c:467
 ret_from_fork+0x51e/0xb90 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 ffff88802ba7a000
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 24 bytes inside of
 freed 256-byte region [ffff88802ba7a000, ffff88802ba7a100)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88802ba7a000 pfn:0x2ba7a
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000240(workingset|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000240 ffff88801b041b40 ffffea0001dbac10 ffffea0000e25e90
raw: ffff88802ba7a000 000000000010000f 00000000f5000000 0000000000000000
head: 00fff00000000240 ffff88801b041b40 ffffea0001dbac10 ffffea0000e25e90
head: ffff88802ba7a000 000000000010000f 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0000ae9e81 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 1, tgid 1 (swapper/0), ts 11297336772, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_slab_page mm/slub.c:3255 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3444
 new_slab mm/slub.c:3502 [inline]
 refill_objects+0x331/0x3c0 mm/slub.c:7134
 refill_sheaf mm/slub.c:2804 [inline]
 __pcs_replace_empty_main+0x2b9/0x620 mm/slub.c:4578
 alloc_from_pcs mm/slub.c:4681 [inline]
 slab_alloc_node mm/slub.c:4815 [inline]
 __kmalloc_cache_noprof+0x392/0x660 mm/slub.c:5334
 kmalloc_noprof include/linux/slab.h:962 [inline]
 kzalloc_noprof include/linux/slab.h:1204 [inline]
 bus_add_driver+0x162/0x670 drivers/base/bus.c:699
 driver_register+0x23a/0x320 drivers/base/driver.c:249
 usb_register_driver+0x1e4/0x390 drivers/usb/core/driver.c:1078
 do_one_initcall+0x250/0x8d0 init/main.c:1382
 do_initcall_level+0x104/0x190 init/main.c:1444
 do_initcalls+0x59/0xa0 init/main.c:1460
 kernel_init_freeable+0x2a6/0x3e0 init/main.c:1692
 kernel_init+0x1d/0x1d0 init/main.c:1582
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88802ba79f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802ba79f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802ba7a000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88802ba7a080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802ba7a100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================