bisecting fixing commit since 14b58326976de6ef3998eefec1dd7f8b38b97a75 building syzkaller on ff51e5229e0ee846d2fd687cb0dbca13de758c66 testing commit 14b58326976de6ef3998eefec1dd7f8b38b97a75 with gcc (GCC) 8.4.1 20210217 kernel signature: 56171b7f9e9413a3046be88ae0ac78a1444464d833eded9d59e38421afdc010f run #0: crashed: KASAN: use-after-free Write in hci_conn_del run #1: crashed: KASAN: use-after-free Write in hci_conn_del run #2: crashed: KASAN: use-after-free Write in hci_conn_del run #3: crashed: KASAN: use-after-free Write in hci_conn_del run #4: crashed: KASAN: use-after-free Write in hci_conn_del run #5: crashed: KASAN: use-after-free Write in hci_conn_del run #6: crashed: KASAN: use-after-free Write in hci_conn_del run #7: crashed: KASAN: slab-out-of-bounds Write in hci_conn_del run #8: crashed: KASAN: use-after-free Write in hci_conn_del run #9: crashed: KASAN: use-after-free Write in hci_conn_del run #10: crashed: KASAN: use-after-free Write in hci_conn_del run #11: crashed: KASAN: use-after-free Write in hci_conn_del run #12: crashed: KASAN: slab-out-of-bounds Write in hci_conn_del run #13: crashed: KASAN: slab-out-of-bounds Write in hci_conn_del run #14: crashed: KASAN: use-after-free Write in hci_conn_del run #15: crashed: KASAN: use-after-free Write in hci_conn_del run #16: crashed: KASAN: use-after-free Read in __queue_work run #17: crashed: KASAN: use-after-free Write in hci_conn_del run #18: crashed: KASAN: use-after-free Write in hci_conn_del run #19: crashed: KASAN: use-after-free Write in hci_conn_del testing current HEAD cf256fbcbe347b7d0ff58fe2dfa382a156bd3694 testing commit cf256fbcbe347b7d0ff58fe2dfa382a156bd3694 with gcc (GCC) 8.4.1 20210217 kernel signature: 14413e5f5a725557bcc4e2d9c0cf20b563b34b53166603e6812ea04ad5ac76ee run #0: crashed: KASAN: use-after-free Write in hci_conn_del run #1: crashed: KASAN: use-after-free Write in hci_conn_del run #2: crashed: KASAN: use-after-free Write in hci_conn_del run #3: crashed: KASAN: use-after-free Write in hci_conn_del run #4: crashed: KASAN: use-after-free Write in hci_conn_del run #5: crashed: KASAN: use-after-free Write in hci_conn_del run #6: crashed: KASAN: use-after-free Write in hci_conn_del run #7: crashed: KASAN: use-after-free Write in hci_conn_del run #8: crashed: KASAN: use-after-free Write in hci_conn_del run #9: crashed: KASAN: use-after-free Read in __queue_work revisions tested: 2, total time: 34m3.678222958s (build: 23m27.537149719s, test: 9m57.210250625s) the crash still happens on HEAD commit msg: Linux 4.14.231 crash: KASAN: use-after-free Read in __queue_work bond0 (unregistering): Released all slaves Bluetooth: hci2 command 0x0405 tx timeout ================================================================== BUG: KASAN: use-after-free in __queue_work+0xa65/0xe40 kernel/workqueue.c:1384 Read of size 4 at addr ffff8881ef1f1c00 by task kworker/1:2/2618 CPU: 1 PID: 2618 Comm: kworker/1:2 Not tainted 4.14.231-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events hci_cmd_timeout Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x14b/0x1e7 lib/dump_stack.c:58 print_address_description.cold.6+0x9/0x1ca mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold.7+0x11a/0x2d3 mm/kasan/report.c:393 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:429 __queue_work+0xa65/0xe40 kernel/workqueue.c:1384 queue_work_on+0x140/0x180 kernel/workqueue.c:1490 queue_work include/linux/workqueue.h:491 [inline] hci_cmd_timeout+0x151/0x1c0 net/bluetooth/hci_core.c:2535 process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 worker_thread+0xcc/0xee0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Allocated by task 24: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:551 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:536 __do_kmalloc mm/slab.c:3720 [inline] __kmalloc+0x15d/0x410 mm/slab.c:3729 kmalloc include/linux/slab.h:493 [inline] kzalloc include/linux/slab.h:661 [inline] __alloc_workqueue_key+0xf8/0xc80 kernel/workqueue.c:4003 hci_register_dev+0x182/0x750 net/bluetooth/hci_core.c:3101 __vhci_create_device+0x269/0x4f0 drivers/bluetooth/hci_vhci.c:139 vhci_create_device drivers/bluetooth/hci_vhci.c:163 [inline] vhci_open_timeout+0x34/0x50 drivers/bluetooth/hci_vhci.c:319 process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 worker_thread+0xcc/0xee0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Freed by task 29: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_slab_free+0xab/0x190 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcc/0x270 mm/slab.c:3815 rcu_free_wq+0x99/0xf0 kernel/workqueue.c:3279 __rcu_reclaim kernel/rcu/rcu.h:195 [inline] rcu_do_batch kernel/rcu/tree.c:2699 [inline] invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline] __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline] rcu_process_callbacks+0x7a5/0x11e0 kernel/rcu/tree.c:2946 __do_softirq+0x247/0x9a2 kernel/softirq.c:288 The buggy address belongs to the object at ffff8881ef1f1a80 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 384 bytes inside of 512-byte region [ffff8881ef1f1a80, ffff8881ef1f1c80) The buggy address belongs to the page: page:ffffea0007bc7c40 count:1 mapcount:0 mapping:ffff8881ef1f1080 index:0x0 flags: 0x17ffe0000000100(slab) raw: 017ffe0000000100 ffff8881ef1f1080 0000000000000000 0000000100000006 raw: ffffea0007a504e0 ffffea00076ebc20 ffff8881f6000940 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881ef1f1b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8881ef1f1b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8881ef1f1c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8881ef1f1c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8881ef1f1d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ================================================================== kasan: CONFIG_KASAN_INLINE enabled kasan: GPF could be caused by NULL-ptr deref or user memory access general protection fault: 0000 [#1] PREEMPT SMP KASAN Modules linked in: CPU: 1 PID: 2618 Comm: kworker/1:2 Tainted: G B 4.14.231-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events hci_cmd_timeout task: ffff8881e8be23c0 task.stack: ffff8881e8be8000 RIP: 0010:__queue_work+0x10e/0xe40 kernel/workqueue.c:1405 RSP: 0018:ffff8881e8befc80 EFLAGS: 00010046 RAX: ffff8881f2472900 RBX: 0000000000000000 RCX: ffff8881f5c00068 RDX: 0000000000000000 RSI: 0000000000000005 RDI: 0000000000000000 RBP: ffff8881e8befcf0 R08: ffffffff87f55680 R09: ffffffff87f55688 R10: 0000000000000000 R11: 0000000000000040 R12: ffff8881de4a9640 R13: ffff8881ef1f1a80 R14: 0000000000000001 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8881f6700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000535f98 CR3: 0000000007e6a003 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: queue_work_on+0x140/0x180 kernel/workqueue.c:1490 queue_work include/linux/workqueue.h:491 [inline] hci_cmd_timeout+0x151/0x1c0 net/bluetooth/hci_core.c:2535 process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 worker_thread+0xcc/0xee0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Code: f7 e8 57 a0 ef ff 4c 89 ef 89 c6 e8 dd 76 ff ff 4c 89 e7 48 89 c3 e8 92 df ff ff 48 85 c0 0f 84 da 02 00 00 48 89 da 48 c1 ea 03 <42> 80 3c 3a 00 0f 85 00 0c 00 00 48 39 03 0f 85 75 04 00 00 48 RIP: __queue_work+0x10e/0xe40 kernel/workqueue.c:1405 RSP: ffff8881e8befc80 ---[ end trace 35a80877dcd1b654 ]---