bisecting fixing commit since 4762bcd451a9e92e79d5146d3d4a5ffe2b4e0ec5
building syzkaller on 048f2d494ee4a016e2386c28bf8cccdd87896cbd
testing commit 4762bcd451a9e92e79d5146d3d4a5ffe2b4e0ec5 with gcc (GCC) 8.1.0
kernel signature: 08a9fffa091d7f1774331a082fc26bcaf71ad136
all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
testing current HEAD 84f5ad468100f86d70096799e4ee716a17c2962f
testing commit 84f5ad468100f86d70096799e4ee716a17c2962f with gcc (GCC) 8.1.0
kernel signature: c9715258f50d22fdd944defae6e1c35e13af1c83
run #0: crashed: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
run #1: crashed: general protection fault in rxrpc_get_skb
run #2: crashed: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
run #6: crashed: general protection fault in rxrpc_get_skb
run #7: crashed: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
run #8: crashed: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
run #9: crashed: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
revisions tested: 2, total time: 24m20.566124077s (build: 16m37.48800697s, test: 6m31.437461909s)
the crash still happens on HEAD
commit msg: Linux 4.14.162
crash: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready
8021q: adding VLAN 0 to HW filter on device batadv0
BUG: unable to handle kernel NULL pointer dereference at 0000000000000268
IP: atomic_add_return arch/x86/include/asm/atomic.h:157 [inline]
IP: rxrpc_send_data_packet+0xc4/0x13b0 net/rxrpc/output.c:281
PGD 9779f067 P4D 9779f067 PUD 77abf067 PMD 0 
Oops: 0002 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 2680 Comm: kworker/1:2 Not tainted 4.14.162-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krxrpcd rxrpc_process_call
task: ffff88809f77a540 task.stack: ffff88809f648000
RIP: 0010:atomic_add_return arch/x86/include/asm/atomic.h:157 [inline]
RIP: 0010:rxrpc_send_data_packet+0xc4/0x13b0 net/rxrpc/output.c:281
RSP: 0018:ffff88809f64fad0 EFLAGS: 00010246
RAX: 0000000000000001 RBX: ffff888078619800 RCX: dffffc0000000000
RDX: 0000000000000001 RSI: ffff8880787a67c0 RDI: ffff888078619810
RBP: ffff88809f64fca0 R08: ffff88809f77ae08 R09: 0000000000000000
R10: ffff88809f64fcb8 R11: 0000000000000000 R12: ffff8880787a67c0
R13: ffff8880787a67c0 R14: 0000000000000001 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000268 CR3: 000000009795d000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 rxrpc_resend net/rxrpc/call_event.c:322 [inline]
 rxrpc_process_call+0x4fb/0xff9 net/rxrpc/call_event.c:407
 process_one_work+0x79e/0x16c0 kernel/workqueue.c:2114
 worker_thread+0xcc/0xee0 kernel/workqueue.c:2248
 kthread+0x338/0x400 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: f2 f2 f2 c7 40 24 00 00 00 f2 c7 40 28 f3 f3 f3 f3 48 89 f8 48 c1 e8 03 80 3c 08 00 0f 85 28 10 00 00 4c 8b 7b 10 b8 01 00 00 00 <f0> 41 0f c1 87 68 02 00 00 83 c0 01 4c 89 f9 48 c1 e9 03 89 85 
RIP: atomic_add_return arch/x86/include/asm/atomic.h:157 [inline] RSP: ffff88809f64fad0
RIP: rxrpc_send_data_packet+0xc4/0x13b0 net/rxrpc/output.c:281 RSP: ffff88809f64fad0
CR2: 0000000000000268
---[ end trace baa3bc909923674a ]---