bisecting fixing commit since 4762bcd451a9e92e79d5146d3d4a5ffe2b4e0ec5
building syzkaller on 048f2d494ee4a016e2386c28bf8cccdd87896cbd
testing commit 4762bcd451a9e92e79d5146d3d4a5ffe2b4e0ec5 with gcc (GCC) 8.1.0
kernel signature: 57233edac770d687ba47d19d0cad90ef6ad7399f0c113ba86afc027a9497782a
all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in rxrpc_send_data_packet
testing current HEAD 4520f06b03ae667e442da1ab9351fd28cd7ac598
testing commit 4520f06b03ae667e442da1ab9351fd28cd7ac598 with gcc (GCC) 8.1.0
kernel signature: 4fcb3af5a626de699d807746b2f4ff4a3c0c02f8cb6ddadb9f0e82946968deab
run #0: crashed: general protection fault in rxrpc_get_skb
run #1: crashed: KASAN: use-after-free Read in rxrpc_see_skb
run #2: crashed: general protection fault in rxrpc_get_skb
run #3: crashed: general protection fault in rxrpc_get_skb
run #4: crashed: general protection fault in rxrpc_get_skb
run #5: crashed: general protection fault in rxrpc_get_skb
run #6: crashed: general protection fault in rxrpc_get_skb
run #7: crashed: KASAN: use-after-free Read in rxrpc_see_skb
run #8: crashed: KASAN: use-after-free Read in rxrpc_see_skb
run #9: crashed: general protection fault in rxrpc_get_skb
revisions tested: 2, total time: 24m14.452159443s (build: 15m29.603175894s, test: 7m48.727259994s)
the crash still happens on HEAD
commit msg: Linux 4.14.175
crash: general protection fault in rxrpc_get_skb
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: 18 Comm: kworker/1:0 Not tainted 4.14.175-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krxrpcd rxrpc_process_call
task: ffff8880a9d5c4c0 task.stack: ffff8880a9d68000
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:atomic_read arch/x86/include/asm/atomic.h:27 [inline]
RIP: 0010:refcount_read include/linux/refcount.h:42 [inline]
RIP: 0010:rxrpc_get_skb+0x57/0x2f0 net/rxrpc/skbuff.c:52
RSP: 0018:ffff8880a9d6fc60 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 00000000000000e4 RCX: 0000000000000000
RDX: 000000000000001c RSI: 000000000000000a RDI: 0000000000000000
RBP: ffff8880a9d6fca8 R08: ffff8880a9d5cdb0 R09: 00000000000033f2
R10: 0000000000000050 R11: ffff8880a9d5c4c0 R12: 000000000000000a
R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000008fec3000 CR4: 00000000001406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 rxrpc_resend net/rxrpc/call_event.c:319 [inline]
 rxrpc_process_call+0x4e1/0xff9 net/rxrpc/call_event.c:407
 process_one_work+0x79e/0x16c0 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: 89 45 d0 48 c7 c0 a0 bd e0 89 48 0f 46 c2 f0 44 0f c1 28 48 8d 9f e4 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 
RIP: __read_once_size include/linux/compiler.h:183 [inline] RSP: ffff8880a9d6fc60
RIP: atomic_read arch/x86/include/asm/atomic.h:27 [inline] RSP: ffff8880a9d6fc60
RIP: refcount_read include/linux/refcount.h:42 [inline] RSP: ffff8880a9d6fc60
RIP: rxrpc_get_skb+0x57/0x2f0 net/rxrpc/skbuff.c:52 RSP: ffff8880a9d6fc60
---[ end trace 26f5f8fc3e1575d1 ]---