syzbot

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BUG: KASAN: slab-use-after-free in dvb_device_open+0x36a/0x3b0 drivers/media/dvb-core/dvbdev.c:99
Read of size 8 at addr ffff8881412c4c18 by task syz.0.9084/25192

CPU: 0 UID: 0 PID: 25192 Comm: syz.0.9084 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 dvb_device_open+0x36a/0x3b0 drivers/media/dvb-core/dvbdev.c:99
 chrdev_open+0x234/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x982/0x1530 fs/open.c:965
 vfs_open+0x82/0x3f0 fs/open.c:1097
 do_open fs/namei.c:3975 [inline]
 path_openat+0x1de4/0x2cb0 fs/namei.c:4134
 do_filp_open+0x20b/0x470 fs/namei.c:4161
 do_sys_openat2+0x11b/0x1d0 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_openat fs/open.c:1468 [inline]
 __se_sys_openat fs/open.c:1463 [inline]
 __x64_sys_openat+0x174/0x210 fs/open.c:1463
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f28eed8f7c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe32586cf8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f28eefe5fa0 RCX: 00007f28eed8f7c9
RDX: 0000000000000001 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007f28eee13f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f28eefe5fa0 R14: 00007f28eefe5fa0 R15: 0000000000000004
 </TASK>

Allocated by task 1:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:400 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:417
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 dvb_register_device+0x1e4/0x2370 drivers/media/dvb-core/dvbdev.c:475
 dvb_register_frontend+0x5a6/0x880 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+0x459/0xa90 drivers/media/test-drivers/vidtv/vidtv_bridge.c:508
 platform_probe+0x106/0x1d0 drivers/base/platform.c:1405
 call_driver_probe drivers/base/dd.c:581 [inline]
 really_probe+0x241/0xa90 drivers/base/dd.c:659
 __driver_probe_device+0x1de/0x440 drivers/base/dd.c:801
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:831
 __driver_attach+0x283/0x580 drivers/base/dd.c:1217
 bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:370
 bus_add_driver+0x2e9/0x690 drivers/base/bus.c:678
 driver_register+0x15c/0x4b0 drivers/base/driver.c:249
 vidtv_bridge_init+0x45/0x80 drivers/media/test-drivers/vidtv/vidtv_bridge.c:598
 do_one_initcall+0x123/0x6e0 init/main.c:1283
 do_initcall_level init/main.c:1345 [inline]
 do_initcalls init/main.c:1361 [inline]
 do_basic_setup init/main.c:1380 [inline]
 kernel_init_freeable+0x5c8/0x920 init/main.c:1593
 kernel_init+0x1c/0x2b0 init/main.c:1483
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 25191:
 kasan_save_stack+0x33/0x60 mm/kasan/common.c:56
 kasan_save_track+0x14/0x30 mm/kasan/common.c:77
 __kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2543 [inline]
 slab_free mm/slub.c:6642 [inline]
 kfree+0x2b8/0x6d0 mm/slub.c:6849
 dvb_free_device drivers/media/dvb-core/dvbdev.c:619 [inline]
 kref_put include/linux/kref.h:65 [inline]
 dvb_device_put.part.0+0x60/0x90 drivers/media/dvb-core/dvbdev.c:632
 dvb_device_put drivers/media/dvb-core/dvbdev.c:631 [inline]
 dvb_device_open+0x2a4/0x3b0 drivers/media/dvb-core/dvbdev.c:113
 chrdev_open+0x234/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x982/0x1530 fs/open.c:965
 vfs_open+0x82/0x3f0 fs/open.c:1097
 do_open fs/namei.c:3975 [inline]
 path_openat+0x1de4/0x2cb0 fs/namei.c:4134
 do_filp_open+0x20b/0x470 fs/namei.c:4161
 do_sys_openat2+0x11b/0x1d0 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_openat fs/open.c:1468 [inline]
 __se_sys_openat fs/open.c:1463 [inline]
 __x64_sys_openat+0x174/0x210 fs/open.c:1463
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8881412c4c00
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 24 bytes inside of
 freed 256-byte region [ffff8881412c4c00, ffff8881412c4d00)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1412c4
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88813ffa6b40 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88813ffa6b40 dead000000000122 0000000000000000
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 057ff00000000001 ffffea000504b101 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 26404167298, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1af/0x220 mm/page_alloc.c:1845
 prep_new_page mm/page_alloc.c:1853 [inline]
 get_page_from_freelist+0x10a3/0x3a30 mm/page_alloc.c:3879
 __alloc_frozen_pages_noprof+0x25f/0x2470 mm/page_alloc.c:5178
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:3059 [inline]
 allocate_slab mm/slub.c:3232 [inline]
 new_slab+0x24a/0x360 mm/slub.c:3286
 ___slab_alloc+0xd79/0x1a50 mm/slub.c:4655
 __slab_alloc.constprop.0+0x63/0x110 mm/slub.c:4778
 __slab_alloc_node mm/slub.c:4854 [inline]
 slab_alloc_node mm/slub.c:5276 [inline]
 __kmalloc_cache_noprof+0x477/0x780 mm/slub.c:5766
 kmalloc_noprof include/linux/slab.h:957 [inline]
 kzalloc_noprof include/linux/slab.h:1094 [inline]
 bus_add_driver+0x92/0x690 drivers/base/bus.c:662
 driver_register+0x15c/0x4b0 drivers/base/driver.c:249
 i2c_register_driver+0xd9/0x1c0 drivers/i2c/i2c-core-base.c:2019
 do_one_initcall+0x123/0x6e0 init/main.c:1283
 do_initcall_level init/main.c:1345 [inline]
 do_initcalls init/main.c:1361 [inline]
 do_basic_setup init/main.c:1380 [inline]
 kernel_init_freeable+0x5c8/0x920 init/main.c:1593
 kernel_init+0x1c/0x2b0 init/main.c:1483
 ret_from_fork+0x675/0x7d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8881412c4b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8881412c4b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8881412c4c00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff8881412c4c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8881412c4d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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