bisecting fixing commit since a844dc4c544291470aa69edbe2434b040794e269
building syzkaller on 1508f45368a309a3b1196a342b3d64ce7be4cc43
testing commit a844dc4c544291470aa69edbe2434b040794e269 with gcc (GCC) 8.1.0
kernel signature: 015172a088c8adee51445a16d2bf88917e71877b27aa9174adcded1aa5fe3965
all runs: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
testing current HEAD 27ce4f2a6817e38ca74c643d47a96359f6cc0c1c
testing commit 27ce4f2a6817e38ca74c643d47a96359f6cc0c1c with gcc (GCC) 8.1.0
kernel signature: f4814ea37d796335cac020118dcb01096237370520924dc003566c0599861867
all runs: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
revisions tested: 2, total time: 23m12.059359586s (build: 17m4.657316254s, test: 5m12.263890397s)
the crash still happens on HEAD
commit msg: Linux 4.14.206
crash: KASAN: null-ptr-deref Read in llcp_sock_getname
IPv6: ADDRCONF(NETDEV_CHANGE): bridge0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): bridge0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bridge: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): bridge_slave_1: link becomes ready
==================================================================
BUG: KASAN: null-ptr-deref in memcpy include/linux/string.h:372 [inline]
BUG: KASAN: null-ptr-deref in llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532
bridge0: port 2(bridge_slave_1) entered blocking state
Read of size 43 at addr           (null) by task syz-executor.1/7327
bridge0: port 2(bridge_slave_1) entered forwarding state

CPU: 0 PID: 7327 Comm: syz-executor.1 Not tainted 4.14.206-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
IPv6: ADDRCONF(NETDEV_UP): vxcan0: link is not ready
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready
 memcpy include/linux/string.h:372 [inline]
 llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532
 SYSC_getpeername+0x122/0x250 net/socket.c:1715
8021q: adding VLAN 0 to HW filter on device batadv0
 SyS_getpeername+0x9/0x10 net/socket.c:1699
 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45a779
RSP: 002b:00007f24cc585c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000034
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a779
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f24cc5866d4
R13: 00000000004c14b0 R14: 00000000004d56d8 R15: 00000000ffffffff
==================================================================
IPv6: ADDRCONF(NETDEV_UP): vxcan0: link is not ready