syzbot

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BUG: KASAN: slab-use-after-free in dvb_device_open+0x33f/0x3b0 drivers/media/dvb-core/dvbdev.c:99
Read of size 8 at addr ffff88802c8a8018 by task syz.0.63/6363

CPU: 1 UID: 0 PID: 6363 Comm: syz.0.63 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x156/0x4c9 mm/kasan/report.c:482
 kasan_report+0xdf/0x1e0 mm/kasan/report.c:595
 dvb_device_open+0x33f/0x3b0 drivers/media/dvb-core/dvbdev.c:99
 chrdev_open+0x234/0x6a0 fs/char_dev.c:411
 do_dentry_open+0x6d8/0x1660 fs/open.c:949
 vfs_open+0x82/0x3f0 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x208c/0x31a0 fs/namei.c:4830
 do_file_open+0x20e/0x430 fs/namei.c:4859
 do_sys_openat2+0x10d/0x1e0 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+0x12d/0x210 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f228f99bf79
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:00007f229086d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007f228fc16090 RCX: 00007f228f99bf79
RDX: 0000000000000001 RSI: 0000200000000000 RDI: ffffffffffffff9c
RBP: 00007f228fa327e0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f228fc16128 R14: 00007f228fc16090 R15: 00007ffe30059e68
 </TASK>

Allocated by task 1:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
 __kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415
 kmalloc_noprof include/linux/slab.h:962 [inline]
 kzalloc_noprof include/linux/slab.h:1204 [inline]
 dvb_register_device+0x1d6/0x1e60 drivers/media/dvb-core/dvbdev.c:475
 dvb_register_frontend+0x5a8/0x8a0 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+0x44b/0xa30 drivers/media/test-drivers/vidtv/vidtv_bridge.c:508
 platform_probe+0x106/0x1d0 drivers/base/platform.c:1446
 call_driver_probe drivers/base/dd.c:583 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:661
 __driver_probe_device+0x1de/0x400 drivers/base/dd.c:803
 driver_probe_device+0x4c/0x1b0 drivers/base/dd.c:833
 __driver_attach+0x2f4/0x6a0 drivers/base/dd.c:1227
 bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383
 bus_add_driver+0x305/0x5b0 drivers/base/bus.c:715
 driver_register+0x1e2/0x360 drivers/base/driver.c:249
 vidtv_bridge_init+0x38/0x70 drivers/media/test-drivers/vidtv/vidtv_bridge.c:598
 do_one_initcall+0x11d/0x760 init/main.c:1382
 do_initcall_level init/main.c:1444 [inline]
 do_initcalls init/main.c:1460 [inline]
 do_basic_setup init/main.c:1479 [inline]
 kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
 kernel_init+0x1f/0x1e0 init/main.c:1582
 ret_from_fork+0x754/0xd80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Freed by task 6357:
 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57
 kasan_save_track+0x14/0x30 mm/kasan/common.c:78
 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5f/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+0x1f6/0x6b0 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.part.0+0x57/0x90 drivers/media/dvb-core/dvbdev.c:632
 dvb_device_put drivers/media/dvb-core/dvbdev.c:631 [inline]
 dvb_device_open+0x2ba/0x3b0 drivers/media/dvb-core/dvbdev.c:113
 chrdev_open+0x234/0x6a0 fs/char_dev.c:411
 do_dentry_open+0x6d8/0x1660 fs/open.c:949
 vfs_open+0x82/0x3f0 fs/open.c:1081
 do_open fs/namei.c:4671 [inline]
 path_openat+0x208c/0x31a0 fs/namei.c:4830
 do_file_open+0x20e/0x430 fs/namei.c:4859
 do_sys_openat2+0x10d/0x1e0 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+0x12d/0x210 fs/open.c:1383
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff88802c8a8000
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 24 bytes inside of
 freed 256-byte region [ffff88802c8a8000, ffff88802c8a8100)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2c8a8
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 ffff88813fe36b40 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88813fe36b40 dead000000000122 0000000000000000
head: 0000000000000000 0000000000100010 00000000f5000000 0000000000000000
head: 00fff00000000001 ffffea0000b22a01 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 18419012224, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x153/0x170 mm/page_alloc.c:1888
 prep_new_page mm/page_alloc.c:1896 [inline]
 get_page_from_freelist+0x111d/0x3140 mm/page_alloc.c:3961
 __alloc_frozen_pages_noprof+0x27c/0x2ba0 mm/page_alloc.c:5249
 alloc_slab_page mm/slub.c:3238 [inline]
 allocate_slab mm/slub.c:3411 [inline]
 new_slab+0xa6/0x6e0 mm/slub.c:3469
 refill_objects+0x26b/0x400 mm/slub.c:7091
 refill_sheaf mm/slub.c:2787 [inline]
 alloc_full_sheaf mm/slub.c:2808 [inline]
 __pcs_replace_empty_main+0x19f/0x600 mm/slub.c:4546
 alloc_from_pcs mm/slub.c:4639 [inline]
 slab_alloc_node mm/slub.c:4773 [inline]
 __kmalloc_cache_noprof+0x493/0x6f0 mm/slub.c:5292
 kmalloc_noprof include/linux/slab.h:962 [inline]
 kzalloc_noprof include/linux/slab.h:1204 [inline]
 bus_add_driver+0x92/0x5b0 drivers/base/bus.c:699
 driver_register+0x1e2/0x360 drivers/base/driver.c:249
 usb_register_driver drivers/usb/core/driver.c:1078 [inline]
 usb_register_driver+0x21c/0x3e0 drivers/usb/core/driver.c:1060
 do_one_initcall+0x11d/0x760 init/main.c:1382
 do_initcall_level init/main.c:1444 [inline]
 do_initcalls init/main.c:1460 [inline]
 do_basic_setup init/main.c:1479 [inline]
 kernel_init_freeable+0x6e5/0x7a0 init/main.c:1692
 kernel_init+0x1f/0x1e0 init/main.c:1582
 ret_from_fork+0x754/0xd80 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:
 ffff88802c8a7f00: fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc
 ffff88802c8a7f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802c8a8000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88802c8a8080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802c8a8100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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