bisecting fixing commit since ac3a0c8472969a03c0496ae774b3a29eb26c8d5a
building syzkaller on 63a7334112fa63edb0c0a3f317d3d92135a6ead9
testing commit ac3a0c8472969a03c0496ae774b3a29eb26c8d5a with gcc (GCC) 8.1.0
kernel signature: 6f06748327b273e7741e6157f6f148ffd61844bfdca95211ce555149bed5882c
run #0: crashed: general protection fault in hci_send_acl
run #1: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #2: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #6: crashed: general protection fault in hci_send_acl
run #7: crashed: general protection fault in hci_send_acl
run #8: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #9: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
testing current HEAD 71c061d2443814de15e177489d5cc00a4a253ef3
testing commit 71c061d2443814de15e177489d5cc00a4a253ef3 with gcc (GCC) 8.1.0
kernel signature: eaa010da88552fb8464cfb0d9108c5205b2533ebbdba2af583e4b0b628f936e7
run #0: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #1: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #2: crashed: stack segment fault in hci_send_acl
run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #5: crashed: BUG: unable to handle kernel paging request in hci_send_acl
run #6: crashed: BUG: unable to handle kernel paging request in hci_send_acl
run #7: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #8: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
run #9: crashed: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
revisions tested: 2, total time: 15m47.020066669s (build: 9m42.456918628s, test: 5m26.600993259s)
the crash still happens on HEAD
commit msg: Merge tag 'for-5.11-rc2-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
crash: BUG: unable to handle kernel NULL pointer dereference in hci_send_acl
BUG: kernel NULL pointer dereference, address: 0000000000000908
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 10eafc067 P4D 10eafc067 PUD 10eafb067 PMD 0 
Oops: 0000 [#1] PREEMPT SMP
CPU: 0 PID: 1558 Comm: kworker/u5:0 Not tainted 5.11.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: hci0 hci_rx_work
RIP: 0010:hci_send_acl+0x20/0x160 net/bluetooth/hci_core.c:4256
Code: c3 66 0f 1f 84 00 00 00 00 00 41 57 49 89 ff 41 56 49 89 f6 41 55 41 54 55 53 89 d3 0f b7 d2 48 83 ec 10 4c 8b 67 18 8b 46 74 <49> 8b ac 24 08 09 00 00 c7 46 74 00 00 00 00 29 46 70 c6 46 28 02
RSP: 0018:ffffc9000292bcd8 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000002 RCX: ffff888115fcc000
RDX: 0000000000000002 RSI: ffff88810cbc6600 RDI: ffff888115e70000
RBP: ffffc9000292bdf8 R08: 00000000000000c0 R09: ffff888115ef7200
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: ffff888116045211 R14: ffff88810cbc6600 R15: ffff888115e70000
FS:  0000000000000000(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000908 CR3: 000000010eafd001 CR4: 00000000001706f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 l2cap_send_move_chan_cfm_icid+0x46/0x70 net/bluetooth/l2cap_core.c:4922
 l2cap_move_fail net/bluetooth/l2cap_core.c:5406 [inline]
 l2cap_move_channel_rsp net/bluetooth/l2cap_core.c:5445 [inline]
 l2cap_bredr_sig_cmd net/bluetooth/l2cap_core.c:5724 [inline]
 l2cap_sig_channel net/bluetooth/l2cap_core.c:6423 [inline]
 l2cap_recv_frame+0xbe3/0x2e40 net/bluetooth/l2cap_core.c:7666
 hci_acldata_packet net/bluetooth/hci_core.c:4785 [inline]
 hci_rx_work+0x1d3/0x500 net/bluetooth/hci_core.c:4976
 process_one_work+0x293/0x600 kernel/workqueue.c:2275
 worker_thread+0x38/0x380 kernel/workqueue.c:2421
 kthread+0x145/0x170 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296
Modules linked in:
CR2: 0000000000000908
---[ end trace fce37446cfdc0671 ]---
RIP: 0010:hci_send_acl+0x20/0x160 net/bluetooth/hci_core.c:4256
Code: c3 66 0f 1f 84 00 00 00 00 00 41 57 49 89 ff 41 56 49 89 f6 41 55 41 54 55 53 89 d3 0f b7 d2 48 83 ec 10 4c 8b 67 18 8b 46 74 <49> 8b ac 24 08 09 00 00 c7 46 74 00 00 00 00 29 46 70 c6 46 28 02
RSP: 0018:ffffc9000292bcd8 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000002 RCX: ffff888115fcc000
RDX: 0000000000000002 RSI: ffff88810cbc6600 RDI: ffff888115e70000
RBP: ffffc9000292bdf8 R08: 00000000000000c0 R09: ffff888115ef7200
R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000000
R13: ffff888116045211 R14: ffff88810cbc6600 R15: ffff888115e70000
FS:  0000000000000000(0000) GS:ffff888237c00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000908 CR3: 000000010eafd001 CR4: 00000000001706f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400