[syzbot] [media?] KASAN: slab-use-after-free Read in dvb_frontend_release (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cd7a5651db26 alpha: add missing address argument in call t..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1103415a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d9e410399043c26
dashboard link: https://syzkaller.appspot.com/bug?extid=ae466a728017ec940b41
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6546859ef2b7/disk-cd7a5651.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/f2e4c96e79f7/vmlinux-cd7a5651.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7e21013889c0/bzImage-cd7a5651.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ae466a...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in dvb_frontend_release+0x40a/0x4d0 drivers/media/dvb-core/dvb_frontend.c:2916
Read of size 4 at addr ffff88802b33a43c by task syz.0.10208/29088

CPU: 1 UID: 0 PID: 29088 Comm: syz.0.10208 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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_frontend_release+0x40a/0x4d0 drivers/media/dvb-core/dvb_frontend.c:2916
__fput+0x44f/0xa70 fs/file_table.c:469
task_work_run+0x1d9/0x270 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x69b/0x2310 kernel/exit.c:971
do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
get_signal+0x1284/0x1330 kernel/signal.c:3034
arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0a9c79bc0b
Code: Unable to access opcode bytes at 0x7f0a9c79bbe1.
RSP: 002b:00007f0a9d607f00 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: fffffffffffffffc RBX: 0000000000000006 RCX: 00007f0a9c79bc0b
RDX: 00007f0a9d608fd0 RSI: 0000000080085502 RDI: 0000000000000006
RBP: 00007f0a9d608fd0 R08: 0000000000000001 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000080085502
R13: 0000000800000000 R14: 0000000000000000 R15: 00007f0a9c85076a
</TASK>

Allocated by task 1:
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:5297
kmalloc_noprof include/linux/slab.h:962 [inline]
kzalloc_noprof include/linux/slab.h:1204 [inline]
dvb_register_device+0x2fd/0x2210 drivers/media/dvb-core/dvbdev.c:475
dvb_register_frontend+0x649/0x950 drivers/media/dvb-core/dvb_frontend.c:3051
vidtv_bridge_dvb_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:436 [inline]
vidtv_bridge_probe+0x9aa/0xf80 drivers/media/test-drivers/vidtv/vidtv_bridge.c:508
platform_probe+0xf9/0x190 drivers/base/platform.c:1446
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
__driver_attach+0x3e7/0x710 drivers/base/dd.c:1227
bus_for_each_dev+0x23b/0x2c0 drivers/base/bus.c:383
bus_add_driver+0x345/0x670 drivers/base/bus.c:715
driver_register+0x23a/0x320 drivers/base/driver.c:249
vidtv_bridge_init+0x28/0x50 drivers/media/test-drivers/vidtv/vidtv_bridge.c:598
do_one_initcall+0x250/0x840 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
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 29088:
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:2670 [inline]
slab_free mm/slub.c:6082 [inline]
kfree+0x1c1/0x610 mm/slub.c:6399
dvb_free_device drivers/media/dvb-core/dvbdev.c:619 [inline]
kref_put include/linux/kref.h:65 [inline]
dvb_device_put drivers/media/dvb-core/dvbdev.c:632 [inline]
dvb_generic_release+0x11d/0x1b0 drivers/media/dvb-core/dvbdev.c:169
dvb_frontend_release+0x132/0x4d0 drivers/media/dvb-core/dvb_frontend.c:2914
__fput+0x44f/0xa70 fs/file_table.c:469
task_work_run+0x1d9/0x270 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x69b/0x2310 kernel/exit.c:971
do_group_exit+0x21b/0x2d0 kernel/exit.c:1112
get_signal+0x1284/0x1330 kernel/signal.c:3034
arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802b33a400
which belongs to the cache kmalloc-256 of size 256
The buggy address is located 60 bytes inside of
freed 256-byte region [ffff88802b33a400, ffff88802b33a500)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2b33a
head: order:1 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 ffff88813fe9db40 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fe9db40 dead000000000122 0000000000000000
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0000acce81 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 13065394638, free_ts 0
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x231/0x280 mm/page_alloc.c:1883
prep_new_page mm/page_alloc.c:1891 [inline]
get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3956
__alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5244
alloc_slab_page mm/slub.c:3238 [inline]
allocate_slab+0x77/0x660 mm/slub.c:3411
new_slab mm/slub.c:3469 [inline]
refill_objects+0x331/0x3c0 mm/slub.c:7091
refill_sheaf mm/slub.c:2787 [inline]
__pcs_replace_empty_main+0x2b9/0x620 mm/slub.c:4536
alloc_from_pcs mm/slub.c:4639 [inline]
slab_alloc_node mm/slub.c:4773 [inline]
__kmalloc_cache_noprof+0x392/0x660 mm/slub.c:5292
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+0x250/0x840 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:
ffff88802b33a300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88802b33a380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802b33a400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff88802b33a480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88802b33a500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================


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