bisecting fixing commit since fb683b5e3f53a73e761952735736180939a313df
building syzkaller on 1508f45368a309a3b1196a342b3d64ce7be4cc43
testing commit fb683b5e3f53a73e761952735736180939a313df with gcc (GCC) 8.1.0
kernel signature: b40c93aedb2b06e9c4cc59b3a9a1bc257c1e5d3e60091583bd11c35a8d73f6ec
all runs: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname
testing current HEAD 015e94d0e37b6860e4354ce3cac56bd7c39c8992
testing commit 015e94d0e37b6860e4354ce3cac56bd7c39c8992 with gcc (GCC) 8.1.0
kernel signature: f3a26b8c21bd8fdaba5740183a3ee1ccad75ad71bb783a52dc2adba8e97f267f
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 Read 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: KASAN: null-ptr-deref Read in llcp_sock_getname
revisions tested: 2, total time: 22m59.038444621s (build: 16m35.549692671s, test: 5m49.125769107s)
the crash still happens on HEAD
commit msg: Linux 4.19.146
crash: KASAN: null-ptr-deref Read in llcp_sock_getname
IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_hsr: link becomes ready
==================================================================
IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_0: link becomes ready
BUG: KASAN: null-ptr-deref in memcpy include/linux/string.h:373 [inline]
BUG: KASAN: null-ptr-deref in llcp_sock_getname+0x341/0x440 net/nfc/llcp_sock.c:531
Read of size 43 at addr 0000000000000000 by task syz-executor.0/7442

CPU: 1 PID: 7442 Comm: syz-executor.0 Not tainted 4.19.146-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x123/0x177 lib/dump_stack.c:118
 kasan_report_error mm/kasan/report.c:352 [inline]
 kasan_report.cold.9+0x6d/0x309 mm/kasan/report.c:412
 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:373 [inline]
 llcp_sock_getname+0x341/0x440 net/nfc/llcp_sock.c:531
 __sys_getpeername+0x123/0x220 net/socket.c:1735
 __do_sys_getpeername net/socket.c:1748 [inline]
 __se_sys_getpeername net/socket.c:1745 [inline]
 __x64_sys_getpeername+0x6e/0xb0 net/socket.c:1745
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a779
Code: 2d b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 fb b5 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fd001480c78 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: 00007fd0014816d4
R13: 00000000004c14b0 R14: 00000000004d56d8 R15: 00000000ffffffff
==================================================================
IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0: link becomes ready