bisecting fixing commit since b98aebd298246df37b472c52a2ee1023256d02e3
building syzkaller on 04ca72cd45348daab9d896bbec8ea4c2d13455ac
testing commit b98aebd298246df37b472c52a2ee1023256d02e3 with gcc (GCC) 8.1.0
kernel signature: be15d5389515d77a51f8790023f22dd1b0d1c3af
run #0: crashed: KASAN: null-ptr-deref in llcp_sock_getname
run #1: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
run #2: crashed: BUG: unable to handle kernel
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: BUG: unable to handle kernel
run #6: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted
run #7: crashed: BUG: unable to handle kernel
run #8: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted
run #9: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted
testing current HEAD 6d0c334a400db31751c787c411e7187ab59a3f1d
testing commit 6d0c334a400db31751c787c411e7187ab59a3f1d with gcc (GCC) 8.1.0
kernel signature: dc7775e57b4a3678c7aeadb6a4be2c9c57bbb9aa
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: 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: BUG: unable to handle kernel
run #9: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
revisions tested: 2, total time: 23m21.702378478s (build: 16m28.878886955s, test: 6m29.769807722s)
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 63 at addr           (null) by task syz-executor.4/7118

CPU: 1 PID: 7118 Comm: syz-executor.4 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
 sock_getsockopt+0xaf4/0x1921 net/core/sock.c:1276
 SYSC_getsockopt net/socket.c:1892 [inline]
 SyS_getsockopt+0x1b6/0x1e0 net/socket.c:1878
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459f39
RSP: 002b:00007fe172de3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459f39
RDX: 000000000000001c RSI: 0000000000000001 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000020000140 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fe172de46d4
R13: 00000000004c1408 R14: 00000000004d4ae0 R15: 00000000ffffffff
==================================================================