================================================================== BUG: KASAN: slab-use-after-free in dvb_device_open+0xca/0x370 drivers/media/dvb-core/dvbdev.c:99 Read of size 8 at addr ffff888026f00818 by task syz.4.4366/21928 CPU: 0 PID: 21928 Comm: syz.4.4366 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:364 [inline] print_report+0xa8/0x210 mm/kasan/report.c:468 kasan_report+0x117/0x150 mm/kasan/report.c:581 dvb_device_open+0xca/0x370 drivers/media/dvb-core/dvbdev.c:99 chrdev_open+0x5cc/0x6a0 fs/char_dev.c:414 do_dentry_open+0x8c6/0x1500 fs/open.c:929 do_open fs/namei.c:3640 [inline] path_openat+0x27f1/0x3230 fs/namei.c:3797 do_filp_open+0x1f5/0x430 fs/namei.c:3824 do_sys_openat2+0x134/0x1d0 fs/open.c:1421 do_sys_open fs/open.c:1436 [inline] __do_sys_openat fs/open.c:1452 [inline] __se_sys_openat fs/open.c:1447 [inline] __x64_sys_openat+0x139/0x160 fs/open.c:1447 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f3bfd55d68e 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 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08 RSP: 002b:00007f3bfe4ddb28 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f3bfe4de6c0 RCX: 00007f3bfd55d68e RDX: 0000000000000002 RSI: 00007f3bfe4ddc00 RDI: ffffffffffffff9c RBP: 00007f3bfe4ddc00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: cccccccccccccccd R13: 00007f3bfd816128 R14: 00007f3bfd816090 R15: 00007ffeacc48c88 Allocated by task 21378: kasan_save_stack mm/kasan/common.c:46 [inline] kasan_set_track+0x4e/0x70 mm/kasan/common.c:53 ____kasan_kmalloc mm/kasan/common.c:375 [inline] __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384 kmalloc include/linux/slab.h:600 [inline] kzalloc include/linux/slab.h:721 [inline] ll_open+0x5e/0x300 drivers/bluetooth/hci_ll.c:117 hci_uart_register_dev drivers/bluetooth/hci_ldisc.c:678 [inline] hci_uart_set_proto drivers/bluetooth/hci_ldisc.c:714 [inline] hci_uart_tty_ioctl+0x77b/0x9f0 drivers/bluetooth/hci_ldisc.c:768 tty_ioctl+0x9bd/0xdd0 drivers/tty/tty_io.c:2788 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xfd/0x170 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 The buggy address belongs to the object at ffff888026f00800 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 24 bytes inside of freed 256-byte region [ffff888026f00800, ffff888026f00900) The buggy address belongs to the physical page: page:ffffea00009bc000 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888026f00800 pfn:0x26f00 head:ffffea00009bc000 order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 00fff00000000840 ffff888017c41b40 ffffea0000ba7590 ffffea0000b45290 raw: ffff888026f00800 000000000010000f 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 2, tgid 2 (kthreadd), ts 19607347542, free_ts 0 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1581 prep_new_page mm/page_alloc.c:1588 [inline] get_page_from_freelist+0x1951/0x19e0 mm/page_alloc.c:3220 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4500 alloc_slab_page+0x5d/0x160 mm/slub.c:1881 allocate_slab mm/slub.c:2028 [inline] new_slab+0x87/0x2d0 mm/slub.c:2081 ___slab_alloc+0xc5d/0x12f0 mm/slub.c:3253 __slab_alloc mm/slub.c:3339 [inline] __slab_alloc_node mm/slub.c:3392 [inline] slab_alloc_node mm/slub.c:3485 [inline] __kmem_cache_alloc_node+0x19e/0x250 mm/slub.c:3534 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098 kmalloc include/linux/slab.h:600 [inline] kzalloc include/linux/slab.h:721 [inline] set_kthread_struct+0xb7/0x1f0 kernel/kthread.c:118 copy_process+0x10a3/0x3d80 kernel/fork.c:2434 kernel_clone+0x24b/0x8a0 kernel/fork.c:2915 kernel_thread+0x13f/0x1b0 kernel/fork.c:2977 create_kthread kernel/kthread.c:411 [inline] kthreadd+0x57f/0x750 kernel/kthread.c:766 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293 page_owner free stack trace missing Memory state around the buggy address: ffff888026f00700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888026f00780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888026f00800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888026f00880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888026f00900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================