bisecting fixing commit since ddef1e8e3f6eb26034833b7255e3fa584d54a230
building syzkaller on 5ea87a6638e52a94361b26b8576a1605585815fb
testing commit ddef1e8e3f6eb26034833b7255e3fa584d54a230 with gcc (GCC) 8.1.0
kernel signature: 06974e3faeec3ab7f763c10884651b167916a57c
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: 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: KASAN: null-ptr-deref in llcp_sock_getname
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 Read in llcp_sock_getname
testing current HEAD 6d0c334a400db31751c787c411e7187ab59a3f1d
testing commit 6d0c334a400db31751c787c411e7187ab59a3f1d with gcc (GCC) 8.1.0
kernel signature: b3523adcd6d1871b18e136373235aa6bcddf7f05
all runs: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
revisions tested: 2, total time: 23m16.492757132s (build: 16m15.517675808s, test: 6m24.986858824s)
the crash still happens on HEAD
commit msg: Linux 4.14.164
crash: KASAN: null-ptr-deref Read in llcp_sock_getname
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: 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
Read of size 43 at addr           (null) by task syz-executor.1/7113

CPU: 0 PID: 7113 Comm: syz-executor.1 Not tainted 4.14.164-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xf7/0x13b lib/dump_stack.c:58
 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
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:347 [inline]
 llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532
 SYSC_getpeername+0x122/0x250 net/socket.c:1715
BUG: unable to handle kernel 
NULL pointer dereference
 at           (null)
 SyS_getpeername+0x9/0x10 net/socket.c:1699
IP: memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
PGD 9a33b067 
P4D 9a33b067 
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
PUD 7717a067 
RIP: 0033:0x459f49
PMD 0 
RSP: 002b:00007f6e82c77c78 EFLAGS: 00000246
 ORIG_RAX: 0000000000000034
Oops: 0000 [#1] PREEMPT SMP KASAN
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459f49
Modules linked in:
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6e82c786d4
CPU: 1 PID: 7112 Comm: syz-executor.0 Not tainted 4.14.164-syzkaller #0
R13: 00000000004c0bf0 R14: 00000000004d37a8 R15: 00000000ffffffff
==================================================================
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011