bisecting fixing commit since b98aebd298246df37b472c52a2ee1023256d02e3
building syzkaller on 04ca72cd45348daab9d896bbec8ea4c2d13455ac
testing commit b98aebd298246df37b472c52a2ee1023256d02e3 with gcc (GCC) 8.1.0
kernel signature: 1a9accacf7d7b02d9900836f2cda7243a64c0a0d227fc1e8d3949422b7081a27
run #0: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #1: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted
run #2: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #3: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #4: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #5: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #6: crashed: BUG: unable to handle kernel
run #7: crashed: BUG: unable to handle kernel
run #8: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #9: crashed: BUG: unable to handle kernel
testing current HEAD e0f8b8a65a473a8baa439cf865a694bbeb83fe90
testing commit e0f8b8a65a473a8baa439cf865a694bbeb83fe90 with gcc (GCC) 8.1.0
kernel signature: e40d8c464dec0e00c66d700f235faf3664bd73018084d89dfb5afebb74cfdd4b
run #0: crashed: BUG: unable to handle kernel
run #1: crashed: BUG: unable to handle kernel
run #2: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted
run #4: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #5: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #6: crashed: BUG: unable to handle kernel
run #7: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #8: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #9: crashed: BUG: unable to handle kernel
revisions tested: 2, total time: 23m28.228098303s (build: 16m42.946486434s, test: 6m21.296622314s)
the crash still happens on HEAD
commit msg: Linux 4.14.170
crash: BUG: unable to handle kernel
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
8021q: adding VLAN 0 to HW filter on device batadv0
8021q: adding VLAN 0 to HW filter on device batadv0
==================================================================
BUG: unable to handle kernel 
BUG: KASAN: null-ptr-deref in memcpy include/linux/string.h:347 [inline]
BUG: KASAN: null-ptr-deref in llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532
NULL pointer dereference
Read of size 63 at addr           (null) by task syz-executor.4/7135

 at           (null)
CPU: 0 PID: 7135 Comm: syz-executor.4 Not tainted 4.14.170-syzkaller #0
IP: memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
PGD 9b746067 
Call Trace:
P4D 9b746067 
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xf7/0x13b lib/dump_stack.c:58
PUD 9b747067 
PMD 0 
 kasan_report_error mm/kasan/report.c:349 [inline]
 kasan_report.cold.8+0x6d/0x2d3 mm/kasan/report.c:409
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
Oops: 0000 [#1] PREEMPT SMP KASAN
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
Modules linked in:
 memcpy include/linux/string.h:347 [inline]
 llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532
 sock_getsockopt+0xaf4/0x1921 net/core/sock.c:1276
CPU: 1 PID: 7132 Comm: syz-executor.0 Not tainted 4.14.170-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880a53d83c0 task.stack: ffff888081318000
RIP: 0010:memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54
RSP: 0018:ffff88808131fb10 EFLAGS: 00010246
RAX: ffff88808131fd42 RBX: 000000000000003f RCX: 000000000000003f
RDX: 000000000000003f RSI: 0000000000000000 RDI: ffff88808131fd42
 SYSC_getsockopt net/socket.c:1892 [inline]
 SyS_getsockopt+0x1b6/0x1e0 net/socket.c:1878
RBP: ffff88808131fb30 R08: ffffed1010263fb1 R09: ffffed1010263fa8
R10: ffffed1010263fb0 R11: ffff88808131fd80 R12: ffff88808131fd42
R13: 0000000000000000 R14: ffff8880848f1210 R15: ffff8880848f0dc0
FS:  00007f5ef5f20700(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 000000008575d000 CR4: 00000000001406e0
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
Call Trace:
RIP: 0033:0x459f39
RSP: 002b:00007f2a328d2c78 EFLAGS: 00000246
 ORIG_RAX: 0000000000000037
 memcpy include/linux/string.h:347 [inline]
 llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459f39
 sock_getsockopt+0xaf4/0x1921 net/core/sock.c:1276
RDX: 000000000000001c RSI: 0000000000000001 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000020000140 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f2a328d36d4
R13: 00000000004c1408 R14: 00000000004d4ae0 R15: 00000000ffffffff
==================================================================