bisecting fixing commit since f8788d86ab28f61f7b46eb6be375f8a726783636 building syzkaller on 59b57593586656c1d5be820aeed0e751087e6ac6 testing commit f8788d86ab28f61f7b46eb6be375f8a726783636 with gcc (GCC) 8.1.0 kernel signature: 192b4e39ff60c675ac1f12bab210c8c6db6500c016102273cc18365e9b017662 run #0: crashed: WARNING: locking bug in finish_task_switch run #1: crashed: WARNING: locking bug in finish_task_switch run #2: crashed: WARNING: locking bug in finish_task_switch run #3: crashed: WARNING: locking bug in finish_task_switch run #4: crashed: WARNING: locking bug in finish_task_switch run #5: crashed: WARNING: locking bug in finish_task_switch run #6: crashed: KASAN: use-after-free Write in hci_sock_bind run #7: crashed: WARNING: locking bug in finish_task_switch run #8: crashed: WARNING: locking bug in finish_task_switch run #9: crashed: WARNING: locking bug in finish_task_switch testing current HEAD 1a323ea5356edbb3073dc59d51b9e6b86908857d testing commit 1a323ea5356edbb3073dc59d51b9e6b86908857d with gcc (GCC) 8.1.0 kernel signature: 3e12639ad3f90a6ce0f748041671488b49b74941d016e098204831f8c5f3c8bf run #0: crashed: WARNING: locking bug in finish_task_switch run #1: crashed: WARNING: locking bug in finish_task_switch run #2: crashed: WARNING: locking bug in finish_task_switch run #3: crashed: WARNING: locking bug in finish_task_switch run #4: crashed: WARNING: locking bug in finish_task_switch run #5: crashed: WARNING: locking bug in finish_task_switch run #6: crashed: WARNING: locking bug in finish_task_switch run #7: crashed: KASAN: use-after-free Write in hci_sock_bind run #8: crashed: WARNING: locking bug in finish_task_switch run #9: crashed: KASAN: use-after-free Write in hci_sock_bind revisions tested: 2, total time: 20m2.448475037s (build: 11m56.098960434s, test: 7m36.563488165s) the crash still happens on HEAD commit msg: x86: get rid of 'errret' argument to __get_user_xyz() macross crash: KASAN: use-after-free Write in hci_sock_bind ================================================================== BUG: KASAN: use-after-free in atomic_inc include/asm-generic/atomic-instrumented.h:239 [inline] BUG: KASAN: use-after-free in hci_sock_bind+0x755/0xfb0 net/bluetooth/hci_sock.c:1250 Write of size 4 at addr ffff88808dc8d250 by task syz-executor.5/27205 CPU: 1 PID: 27205 Comm: syz-executor.5 Not tainted 5.6.0-syzkaller #0 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+0x12d/0x187 lib/dump_stack.c:118 print_address_description.constprop.8.cold.10+0x9/0x31d mm/kasan/report.c:374 __kasan_report.cold.11+0x1b/0x32 mm/kasan/report.c:506 kasan_report+0x12/0x20 mm/kasan/common.c:641 check_memory_region_inline mm/kasan/generic.c:185 [inline] check_memory_region+0x153/0x1d0 mm/kasan/generic.c:192 __kasan_check_write+0x14/0x20 mm/kasan/common.c:101 atomic_inc include/asm-generic/atomic-instrumented.h:239 [inline] hci_sock_bind+0x755/0xfb0 net/bluetooth/hci_sock.c:1250 __sys_bind+0x1e1/0x230 net/socket.c:1662 __do_sys_bind net/socket.c:1673 [inline] __se_sys_bind net/socket.c:1671 [inline] __x64_sys_bind+0x6e/0xb0 net/socket.c:1671 do_syscall_64+0xca/0x630 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 RIP: 0033:0x45c449 Code: ad b6 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 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f300bd68c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000031 RAX: ffffffffffffffda RBX: 00007f300bd696d4 RCX: 000000000045c449 RDX: 0000000000000006 RSI: 00000000200007c0 RDI: 0000000000000005 RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 000000000000002c R14: 00000000004c28c9 R15: 000000000076bf2c Allocated by task 27190: save_stack+0x21/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] __kasan_kmalloc.constprop.17+0xc7/0xd0 mm/kasan/common.c:515 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529 kmem_cache_alloc_trace+0x15b/0x780 mm/slab.c:3551 kmalloc include/linux/slab.h:555 [inline] kzalloc include/linux/slab.h:669 [inline] hci_alloc_dev+0x3f/0x1ec0 net/bluetooth/hci_core.c:3365 __vhci_create_device+0xe1/0x530 drivers/bluetooth/hci_vhci.c:99 vhci_create_device drivers/bluetooth/hci_vhci.c:148 [inline] vhci_get_user drivers/bluetooth/hci_vhci.c:205 [inline] vhci_write+0x284/0x3e0 drivers/bluetooth/hci_vhci.c:285 call_write_iter include/linux/fs.h:1902 [inline] new_sync_write+0x400/0x7e0 fs/read_write.c:483 __vfs_write+0x94/0x110 fs/read_write.c:496 vfs_write+0x190/0x530 fs/read_write.c:558 ksys_write+0x10b/0x220 fs/read_write.c:611 __do_sys_write fs/read_write.c:623 [inline] __se_sys_write fs/read_write.c:620 [inline] __x64_sys_write+0x6e/0xb0 fs/read_write.c:620 do_syscall_64+0xca/0x630 arch/x86/entry/common.c:295 entry_SYSCALL_64_after_hwframe+0x49/0xb3 Freed by task 27142: save_stack+0x21/0x90 mm/kasan/common.c:72 set_track mm/kasan/common.c:80 [inline] kasan_set_free_info mm/kasan/common.c:337 [inline] __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485 __cache_free mm/slab.c:3426 [inline] kfree+0x108/0x2c0 mm/slab.c:3757 bt_host_release+0x10/0x20 net/bluetooth/hci_sysfs.c:86 device_release+0x6a/0x1c0 drivers/base/core.c:1375 kobject_cleanup lib/kobject.c:693 [inline] kobject_release lib/kobject.c:722 [inline] kref_put include/linux/kref.h:65 [inline] kobject_put+0x153/0x220 lib/kobject.c:739 put_device+0xe/0x20 drivers/base/core.c:2632 hci_free_dev+0x10/0x20 net/bluetooth/hci_core.c:3464 vhci_release+0x73/0xe0 drivers/bluetooth/hci_vhci.c:341 __fput+0x269/0x780 fs/file_table.c:280 ____fput+0x9/0x10 fs/file_table.c:313 task_work_run+0xcc/0x160 kernel/task_work.c:123 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x24e/0x2e0 arch/x86/entry/common.c:165 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_64+0x531/0x630 arch/x86/entry/common.c:305 entry_SYSCALL_64_after_hwframe+0x49/0xb3 The buggy address belongs to the object at ffff88808dc8c000 which belongs to the cache kmalloc-8k of size 8192 The buggy address is located 4688 bytes inside of 8192-byte region [ffff88808dc8c000, ffff88808dc8e000) The buggy address belongs to the page: page:ffffea0002372300 refcount:1 mapcount:0 mapping:ffff8880aa4021c0 index:0x0 compound_mapcount: 0 flags: 0xfffe0000010200(slab|head) raw: 00fffe0000010200 ffffea000238e708 ffffea000279d008 ffff8880aa4021c0 raw: 0000000000000000 ffff88808dc8c000 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88808dc8d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808dc8d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88808dc8d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88808dc8d280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88808dc8d300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================