syzbot

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BUG: KASAN: use-after-free in dvb_frontend_release+0x3f8/0x4a0 drivers/media/dvb-core/dvb_frontend.c:2900
Read of size 4 at addr ffff8880293bfc3c by task syz.2.126/4857

CPU: 1 PID: 4857 Comm: syz.2.126 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 dvb_frontend_release+0x3f8/0x4a0 drivers/media/dvb-core/dvb_frontend.c:2900
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f507b39c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffda04778e8 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f507b617da0 RCX: 00007f507b39c819
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f507b617da0 R08: 00007f507b616128 R09: 0000000000000000
R10: 000000000003fdc0 R11: 0000000000000246 R12: 000000000001d56c
R13: 00007f507b61609c R14: 000000000001d364 R15: 00007ffda04779f0
 </TASK>

Allocated by task 1:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 dvb_register_device+0x311/0x2150 drivers/media/dvb-core/dvbdev.c:478
 dvb_register_frontend+0x645/0x920 drivers/media/dvb-core/dvb_frontend.c:3035
 vidtv_bridge_dvb_init drivers/media/test-drivers/vidtv/vidtv_bridge.c:436 [inline]
 vidtv_bridge_probe+0x9a1/0xf70 drivers/media/test-drivers/vidtv/vidtv_bridge.c:508
 platform_probe+0x137/0x1c0 drivers/base/platform.c:1400
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x2aa/0xc70 drivers/base/dd.c:639
 __driver_probe_device+0x18c/0x330 drivers/base/dd.c:785
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:815
 __driver_attach+0x44a/0x6e0 drivers/base/dd.c:1201
 bus_for_each_dev+0x182/0x1f0 drivers/base/bus.c:303
 bus_add_driver+0x30a/0x5a0 drivers/base/bus.c:620
 driver_register+0x32d/0x430 drivers/base/driver.c:246
 vidtv_bridge_init+0x39/0x67 drivers/media/test-drivers/vidtv/vidtv_bridge.c:600
 do_one_initcall+0x26a/0x840 init/main.c:1310
 do_initcall_level+0x137/0x1e4 init/main.c:1383
 do_initcalls+0x4b/0x8a init/main.c:1399
 kernel_init_freeable+0x415/0x5be init/main.c:1638
 kernel_init+0x19/0x1b0 init/main.c:1526
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Freed by task 4857:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x2d/0x50 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1729 [inline]
 slab_free_freelist_hook+0x131/0x1a0 mm/slub.c:1755
 slab_free mm/slub.c:3687 [inline]
 __kmem_cache_free+0xb6/0x1f0 mm/slub.c:3700
 dvb_free_device drivers/media/dvb-core/dvbdev.c:625 [inline]
 kref_put include/linux/kref.h:65 [inline]
 dvb_device_put drivers/media/dvb-core/dvbdev.c:640 [inline]
 dvb_generic_release+0x11c/0x1b0 drivers/media/dvb-core/dvbdev.c:173
 dvb_frontend_release+0x131/0x4a0 drivers/media/dvb-core/dvb_frontend.c:2898
 __fput+0x22c/0x920 fs/file_table.c:320
 task_work_run+0x1d0/0x260 kernel/task_work.c:203
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

The buggy address belongs to the object at ffff8880293bfc00
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 60 bytes inside of
 256-byte region [ffff8880293bfc00, ffff8880293bfd00)

The buggy address belongs to the physical page:
page:ffffea0000a4ef80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x293be
head:ffffea0000a4ef80 order:1 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 0000000000000000 dead000000000122 ffff888017441b40
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
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 19220725308, free_ts 0
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2559
 prep_new_page mm/page_alloc.c:2566 [inline]
 get_page_from_freelist+0x1a1e/0x1ab0 mm/page_alloc.c:4357
 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5657
 alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2115
 alloc_slab_page+0x5d/0x160 mm/slub.c:1799
 allocate_slab mm/slub.c:1944 [inline]
 new_slab+0x87/0x2c0 mm/slub.c:1997
 ___slab_alloc+0xbc6/0x1240 mm/slub.c:3154
 __slab_alloc mm/slub.c:3240 [inline]
 slab_alloc_node mm/slub.c:3325 [inline]
 __kmem_cache_alloc_node+0x1a0/0x260 mm/slub.c:3398
 kmalloc_trace+0x26/0xe0 mm/slab_common.c:1026
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 bus_add_driver+0xda/0x5a0 drivers/base/bus.c:604
 driver_register+0x32d/0x430 drivers/base/driver.c:246
 usb_register_driver+0x202/0x3d0 drivers/usb/core/driver.c:1062
 do_one_initcall+0x26a/0x840 init/main.c:1310
 do_initcall_level+0x137/0x1e4 init/main.c:1383
 do_initcalls+0x4b/0x8a init/main.c:1399
 kernel_init_freeable+0x415/0x5be init/main.c:1638
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8880293bfb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880293bfb80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8880293bfc00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                        ^
 ffff8880293bfc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880293bfd00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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