bisecting fixing commit since b98aebd298246df37b472c52a2ee1023256d02e3
building syzkaller on 04ca72cd45348daab9d896bbec8ea4c2d13455ac
testing commit b98aebd298246df37b472c52a2ee1023256d02e3 with gcc (GCC) 8.1.0
kernel signature: d67bdf61991de1615c703e829ed2c51c7217b987b65aa269be3ab7bf12dba72b
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: BUG: unable to handle kernel NULL pointer dereference in corrupted
run #3: crashed: BUG: unable to handle kernel
run #4: crashed: BUG: unable to handle kernel
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 in llcp_sock_getname
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 12cd844a39ed16aa183a820a54fe6f9a0bb4cd14
testing commit 12cd844a39ed16aa183a820a54fe6f9a0bb4cd14 with gcc (GCC) 8.1.0
kernel signature: 09a1fc07db0e3f5740ef7c08627fe0675fa17b7efd8b125962f150eeb08ace6d
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: BUG: unable to handle kernel
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: 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: 26m17.976872521s (build: 18m23.610586574s, test: 7m6.010106341s)
the crash still happens on HEAD
commit msg: Linux 4.14.173
crash: KASAN: null-ptr-deref Read in llcp_sock_getname
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth0_to_bridge: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1_to_bridge: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bridge: link becomes ready
==================================================================
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
IPv6: ADDRCONF(NETDEV_CHANGE): bridge_slave_0: link becomes ready
Read of size 63 at addr           (null) by task syz-executor.5/7078

CPU: 0 PID: 7078 Comm: syz-executor.5 Not tainted 4.14.173-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
BUG: unable to handle kernel 
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
NULL pointer dereference
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
 at           (null)
 memcpy include/linux/string.h:347 [inline]
 llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532
IP: memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54
 sock_getsockopt+0xaf4/0x1921 net/core/sock.c:1276
PGD 9d8e5067 
P4D 9d8e5067 
PUD 93ce5067 
PMD 0 
Oops: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
 SYSC_getsockopt net/socket.c:1892 [inline]
 SyS_getsockopt+0x1b6/0x1e0 net/socket.c:1878
CPU: 1 PID: 7079 Comm: syz-executor.0 Not tainted 4.14.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880860a8300 task.stack: ffff8880886e8000
RIP: 0010:memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54
RSP: 0018:ffff8880886efb10 EFLAGS: 00010246
RAX: ffff8880886efd42 RBX: 000000000000003f RCX: 000000000000003f
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
RDX: 000000000000003f RSI: 0000000000000000 RDI: ffff8880886efd42
RBP: ffff8880886efb30 R08: ffffed10110ddfb1 R09: ffffed10110ddfa8
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
R10: ffffed10110ddfb0 R11: ffff8880886efd80 R12: ffff8880886efd42
RIP: 0033:0x459f39
R13: 0000000000000000 R14: ffff88809c2127d0 R15: ffff88809c212380
RSP: 002b:00007f9977692c78 EFLAGS: 00000246
FS:  00007fd2af2de700(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000
 ORIG_RAX: 0000000000000037
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459f39
CR2: 0000000000000000 CR3: 000000009db5b000 CR4: 00000000001406e0
RDX: 000000000000001c RSI: 0000000000000001 RDI: 0000000000000004
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
RBP: 000000000075bfc8 R08: 0000000020000140 R09: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f99776936d4
Call Trace:
R13: 00000000004c1408 R14: 00000000004d4ae0 R15: 00000000ffffffff
==================================================================
 memcpy include/linux/string.h:347 [inline]
 llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532