bisecting fixing commit since c076c79e03c6094e578df5d210fde808b3ad32e6 building syzkaller on 4ca1c0ea446d2c09b1fb49a85ae645e3754f1058 testing commit c076c79e03c6094e578df5d210fde808b3ad32e6 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 38684194b0462837400fd596f40f52c4ae2d41fbb5bd825c254927424a127a8a all runs: crashed: BUG: corrupted list in l2cap_chan_put testing current HEAD 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 testing commit 59456c9cc40c8f75b5a7efa0fe1f211d9c6fcaf1 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 546b4a8399b7697721d354ccf07a8c5fa309cc8effa57c270b39fb7a146b4395 run #0: crashed: BUG: corrupted list in l2cap_chan_put run #1: crashed: BUG: corrupted list in l2cap_chan_put run #2: crashed: BUG: corrupted list in l2cap_chan_put run #3: crashed: BUG: corrupted list in l2cap_chan_put run #4: crashed: BUG: corrupted list in l2cap_chan_put run #5: crashed: BUG: corrupted list in l2cap_chan_put run #6: crashed: BUG: corrupted list in l2cap_chan_put run #7: crashed: KASAN: use-after-free Read in l2cap_chan_put run #8: crashed: BUG: corrupted list in l2cap_chan_put run #9: crashed: BUG: corrupted list in l2cap_chan_put revisions tested: 2, total time: 37m10.25709298s (build: 17m52.108746539s, test: 18m50.650800982s) the crash still happens on HEAD commit msg: Linux 4.19.204 crash: BUG: corrupted list in l2cap_chan_put Bluetooth: hci5: command 0x0419 tx timeout Bluetooth: hci4: command 0x0419 tx timeout Bluetooth: hci3: command 0x0419 tx timeout list_del corruption, ffff8881e1074508->next is LIST_POISON1 (dead000000000100) ------------[ cut here ]------------ kernel BUG at lib/list_debug.c:47! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 7328 Comm: kworker/u5:3 Not tainted 4.19.204-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: hci2 hci_rx_work RIP: 0010:__list_del_entry_valid.cold.1+0x26/0x4a lib/list_debug.c:45 Code: f9 ff 0f 0b 4c 89 e2 48 89 de 48 c7 c7 e0 a6 67 87 e8 cb 68 f9 ff 0f 0b 4c 89 ea 48 89 de 48 c7 c7 80 a6 67 87 e8 b7 68 f9 ff <0f> 0b 48 89 de 48 c7 c7 a0 a7 67 87 e8 a6 68 f9 ff 0f 0b 48 89 de RSP: 0018:ffff8881db6ff6f8 EFLAGS: 00010282 RAX: 000000000000004e RBX: ffff8881e1074508 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8767a3e0 RDI: ffffffff8a19faa0 RBP: ffff8881db6ff710 R08: ffffed103ed25081 R09: ffffed103ed25080 R10: ffffed103ed25080 R11: ffff8881f6928407 R12: dead000000000200 R13: dead000000000100 R14: ffff8881d4eba840 R15: ffff8881d4eba8c0 FS: 0000000000000000(0000) GS:ffff8881f6900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004bb868 CR3: 000000000846d006 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __list_del_entry include/linux/list.h:117 [inline] list_del include/linux/list.h:125 [inline] l2cap_chan_destroy net/bluetooth/l2cap_core.c:481 [inline] kref_put include/linux/kref.h:70 [inline] l2cap_chan_put+0x49/0x1a0 net/bluetooth/l2cap_core.c:498 l2cap_conless_channel net/bluetooth/l2cap_core.c:6986 [inline] l2cap_recv_frame+0xf29/0xa430 net/bluetooth/l2cap_core.c:7033 l2cap_recv_acldata+0x756/0x8a0 net/bluetooth/l2cap_core.c:7598 hci_acldata_packet net/bluetooth/hci_core.c:4185 [inline] hci_rx_work+0x5d6/0x8f0 net/bluetooth/hci_core.c:4371 process_one_work+0x7b9/0x15a0 kernel/workqueue.c:2153 worker_thread+0x85/0xb60 kernel/workqueue.c:2296 kthread+0x347/0x410 kernel/kthread.c:259 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415 Modules linked in: ---[ end trace c51c71eee2e78b77 ]--- RIP: 0010:__list_del_entry_valid.cold.1+0x26/0x4a lib/list_debug.c:45 Code: f9 ff 0f 0b 4c 89 e2 48 89 de 48 c7 c7 e0 a6 67 87 e8 cb 68 f9 ff 0f 0b 4c 89 ea 48 89 de 48 c7 c7 80 a6 67 87 e8 b7 68 f9 ff <0f> 0b 48 89 de 48 c7 c7 a0 a7 67 87 e8 a6 68 f9 ff 0f 0b 48 89 de RSP: 0018:ffff8881db6ff6f8 EFLAGS: 00010282 RAX: 000000000000004e RBX: ffff8881e1074508 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8767a3e0 RDI: ffffffff8a19faa0 RBP: ffff8881db6ff710 R08: ffffed103ed25081 R09: ffffed103ed25080 R10: ffffed103ed25080 R11: ffff8881f6928407 R12: dead000000000200 R13: dead000000000100 R14: ffff8881d4eba840 R15: ffff8881d4eba8c0 FS: 0000000000000000(0000) GS:ffff8881f6900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004bb868 CR3: 000000000846d006 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400