bisecting fixing commit since b98aebd298246df37b472c52a2ee1023256d02e3
building syzkaller on 25bb509e5964da8203766c4039e4fef25e4689b1
testing commit b98aebd298246df37b472c52a2ee1023256d02e3 with gcc (GCC) 8.1.0
kernel signature: 2e2e1dda8126f3394389db6d549e2ad513f4594c
run #0: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
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
run #4: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted
run #6: crashed: BUG: unable to handle kernel
run #7: crashed: BUG: unable to handle kernel
run #8: crashed: BUG: unable to handle kernel
run #9: crashed: BUG: unable to handle kernel
testing current HEAD a844dc4c544291470aa69edbe2434b040794e269
testing commit a844dc4c544291470aa69edbe2434b040794e269 with gcc (GCC) 8.1.0
kernel signature: 9aebe6552cffad31e594c7f01af68d2018edcfe1
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 in llcp_sock_getname
run #4: crashed: BUG: unable to handle kernel
run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted
run #6: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted
run #7: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #8: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted
run #9: crashed: KASAN: null-ptr-deref in llcp_sock_getname
revisions tested: 2, total time: 23m4.376123047s (build: 16m12.014962239s, test: 6m22.21368856s)
the crash still happens on HEAD
commit msg: Linux 4.14.158
crash: KASAN: null-ptr-deref in llcp_sock_getname
IPv6: ADDRCONF(NETDEV_UP): hsr0: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
8021q: adding VLAN 0 to HW filter on device batadv0
==================================================================
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
BUG: unable to handle kernel 
Read of size 3 at addr           (null) by task syz-executor.2/6942
NULL pointer dereference at           (null)

IP: memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54
CPU: 1 PID: 6942 Comm: syz-executor.2 Not tainted 4.14.158-syzkaller #0
PGD 9b47a067 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
P4D 9b47a067 PUD 9b47b067 
Call Trace:
PMD 0 
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xf7/0x13b lib/dump_stack.c:58
Oops: 0000 [#1] PREEMPT SMP KASAN
 kasan_report_error mm/kasan/report.c:349 [inline]
 kasan_report.cold.8+0x6d/0x2d3 mm/kasan/report.c:409
Modules linked in:
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
CPU: 0 PID: 6943 Comm: syz-executor.3 Not tainted 4.14.158-syzkaller #0
 memcpy include/linux/string.h:347 [inline]
 llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 SYSC_getpeername+0x122/0x250 net/socket.c:1715
task: ffff888080402180 task.stack: ffff888096c78000
RIP: 0010:memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54
RSP: 0018:ffff888096c7fcb8 EFLAGS: 00010246
RAX: ffff888096c7fe22 RBX: 0000000000000003 RCX: 0000000000000003
RDX: 0000000000000003 RSI: 0000000000000000 RDI: ffff888096c7fe22
RBP: ffff888096c7fcd8 R08: ffffed1012d8ffc5 R09: ffffed1012d8ffc4
 SyS_getpeername+0x9/0x10 net/socket.c:1699
R10: ffffed1012d8ffc4 R11: ffff888096c7fe24 R12: ffff888096c7fe22
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
R13: 0000000000000000 R14: ffff88809bedf250 R15: 0000000000000000
FS:  00007fa34f7d7700(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
RIP: 0033:0x459f39
CR2: 0000000000000000 CR3: 0000000099e17000 CR4: 00000000001406f0
RSP: 002b:00007fd76a0f5c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000034
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459f39
Call Trace:
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
 memcpy include/linux/string.h:347 [inline]
 llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd76a0f66d4
 SYSC_getpeername+0x122/0x250 net/socket.c:1715
R13: 00000000004c0bd0 R14: 00000000004d3668 R15: 00000000ffffffff
==================================================================