================================================================== BUG: KASAN: use-after-free in atomic_dec include/asm-generic/atomic-instrumented.h:127 [inline] BUG: KASAN: use-after-free in hci_sock_release+0x154/0x3c0 net/bluetooth/hci_sock.c:873 Write of size 4 at addr ffff888050c85ce0 by task syz-executor4/29016 CPU: 1 PID: 29016 Comm: syz-executor4 Not tainted 4.20.0+ #8 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1db/0x2d0 lib/dump_stack.c:113 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x123/0x190 mm/kasan/generic.c:191 kasan_check_write+0x14/0x20 mm/kasan/common.c:106 atomic_dec include/asm-generic/atomic-instrumented.h:127 [inline] hci_sock_release+0x154/0x3c0 net/bluetooth/hci_sock.c:873 __sock_release+0xd3/0x250 net/socket.c:579 sock_close+0x1b/0x30 net/socket.c:1141 __fput+0x3c5/0xb10 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x1f4/0x2b0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x32a/0x3b0 arch/x86/entry/common.c:166 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x457ec9 Code: 6d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007ff210518c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000003 RAX: 0000000000000000 RBX: 00007ff210518c90 RCX: 0000000000457ec9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005 RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff2105196d4 R13: 00000000004f4352 R14: 00000000004ce498 R15: 0000000000000007 Allocated by task 29016: save_stack+0x45/0xd0 mm/kasan/common.c:73 set_track mm/kasan/common.c:85 [inline] kasan_kmalloc mm/kasan/common.c:482 [inline] kasan_kmalloc+0xcf/0xe0 mm/kasan/common.c:455 kmem_cache_alloc_trace+0x151/0x760 mm/slab.c:3607 kmalloc include/linux/slab.h:545 [inline] kzalloc include/linux/slab.h:740 [inline] hci_alloc_dev+0x148/0x21a0 net/bluetooth/hci_core.c:3116 __vhci_create_device+0x101/0x5a0 drivers/bluetooth/hci_vhci.c:114 vhci_create_device drivers/bluetooth/hci_vhci.c:163 [inline] vhci_get_user drivers/bluetooth/hci_vhci.c:219 [inline] vhci_write+0x2d0/0x470 drivers/bluetooth/hci_vhci.c:299 call_write_iter include/linux/fs.h:1862 [inline] new_sync_write fs/read_write.c:474 [inline] __vfs_write+0x764/0xb40 fs/read_write.c:487 vfs_write+0x20c/0x580 fs/read_write.c:549 ksys_write+0x105/0x260 fs/read_write.c:598 __do_sys_write fs/read_write.c:610 [inline] __se_sys_write fs/read_write.c:607 [inline] __x64_sys_write+0x73/0xb0 fs/read_write.c:607 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 29010: save_stack+0x45/0xd0 mm/kasan/common.c:73 set_track mm/kasan/common.c:85 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:444 kasan_slab_free+0xe/0x10 mm/kasan/common.c:452 __cache_free mm/slab.c:3485 [inline] kfree+0xcf/0x230 mm/slab.c:3804 bt_host_release+0x19/0x30 net/bluetooth/hci_sysfs.c:86 device_release+0x7d/0x210 drivers/base/core.c:919 kobject_cleanup lib/kobject.c:662 [inline] kobject_release lib/kobject.c:691 [inline] kref_put include/linux/kref.h:67 [inline] kobject_put.cold+0x28f/0x2ec lib/kobject.c:708 put_device+0x20/0x30 drivers/base/core.c:2060 hci_free_dev+0x19/0x20 net/bluetooth/hci_core.c:3208 vhci_release+0x7e/0xf0 drivers/bluetooth/hci_vhci.c:355 __fput+0x3c5/0xb10 fs/file_table.c:278 ____fput+0x16/0x20 fs/file_table.c:309 task_work_run+0x1f4/0x2b0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x32a/0x3b0 arch/x86/entry/common.c:166 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline] syscall_return_slowpath arch/x86/entry/common.c:268 [inline] do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888050c84c80 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 4192 bytes inside of 8192-byte region [ffff888050c84c80, ffff888050c86c80) The buggy address belongs to the page: page:ffffea0001432100 count:1 mapcount:0 mapping:ffff88812c3f2080 index:0x0 compound_mapcount: 0 flags: 0x1fffc0000010200(slab|head) raw: 01fffc0000010200 ffffea0002a0c808 ffffea00015e3b08 ffff88812c3f2080 raw: 0000000000000000 ffff888050c84c80 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888050c85b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888050c85c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888050c85c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888050c85d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888050c85d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ================================================================== ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 1 PID: 29023 at lib/refcount.c:187 refcount_sub_and_test_checked+0x27a/0x2f0 lib/refcount.c:187