bisecting fixing commit since b98aebd298246df37b472c52a2ee1023256d02e3
building syzkaller on 25bb509e5964da8203766c4039e4fef25e4689b1
testing commit b98aebd298246df37b472c52a2ee1023256d02e3 with gcc (GCC) 8.1.0
kernel signature: edd8a616d39d34ea6995ea8cc12a22a88375ccde22f861b5d112714b5a22eab2
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: KASAN: null-ptr-deref Read in llcp_sock_getname
run #4: crashed: KASAN: null-ptr-deref in llcp_sock_getname
run #5: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #6: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
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
testing current HEAD c6db52a88798e5a0dfef80041ad4d33cc8cf04eb
testing commit c6db52a88798e5a0dfef80041ad4d33cc8cf04eb with gcc (GCC) 8.1.0
kernel signature: 8b192d5490a177429180324240d55e885c2c6968ad51eb5125bf01b4ebb38d4a
run #0: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #1: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
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 in llcp_sock_getname
run #5: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #6: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
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: 23m54.079395765s (build: 16m56.164086791s, test: 5m59.715707426s)
the crash still happens on HEAD
commit msg: Linux 4.14.183
crash: BUG: unable to handle kernel
IPv6: ADDRCONF(NETDEV_CHANGE): hsr0: link becomes ready
8021q: adding VLAN 0 to HW filter on device batadv0
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
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 at           (null)
Read of size 3 at addr           (null) by task syz-executor.1/7229
IP: memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54

PGD 8e262067 
CPU: 1 PID: 7229 Comm: syz-executor.1 Not tainted 4.14.183-syzkaller #0
P4D 8e262067 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
PUD 8e19a067 
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: 7233 Comm: syz-executor.4 Not tainted 4.14.183-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: ffff88808e332080 task.stack: ffff8880932a0000
RIP: 0010:memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54
RSP: 0018:ffff8880932a7cb8 EFLAGS: 00010246
RAX: ffff8880932a7e22 RBX: 0000000000000003 RCX: 0000000000000003
RDX: 0000000000000003 RSI: 0000000000000000 RDI: ffff8880932a7e22
RBP: ffff8880932a7cd8 R08: ffffed1012654fc5 R09: ffffed1012654fc4
R10: ffffed1012654fc4 R11: ffff8880932a7e24 R12: ffff8880932a7e22
 SyS_getpeername+0x9/0x10 net/socket.c:1699
R13: 0000000000000000 R14: ffff88808daf2f10 R15: 0000000000000000
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
FS:  00007fe090895700(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
CR2: 0000000000000000 CR3: 000000008d849000 CR4: 00000000001406f0
RIP: 0033:0x459f39
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
RSP: 002b:00007fd147998c78 EFLAGS: 00000246
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 ORIG_RAX: 0000000000000034
Call Trace:
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459f39
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
 memcpy include/linux/string.h:347 [inline]
 llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
 SYSC_getpeername+0x122/0x250 net/socket.c:1715
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd1479996d4
R13: 00000000004c0bd0 R14: 00000000004d3668 R15: 00000000ffffffff
==================================================================
 SyS_getpeername+0x9/0x10 net/socket.c:1699