bisecting fixing commit since 14260788bbb9c94b0e36abc17294266b69dd46e4 building syzkaller on 3a75be00f50996031dd301d44b009d56db3485f0 testing commit 14260788bbb9c94b0e36abc17294266b69dd46e4 with gcc (GCC) 8.4.1 20210217 kernel signature: 5fb6e3c290df23fd30605cf9de025e6ad6702e06e2e72af09a5783b6739ce2ac 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: 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 Read 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 run #10: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted run #11: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #12: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #13: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted run #14: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #15: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #16: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #17: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #18: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #19: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted testing current HEAD 2d19be4653f5e74ed95560b69f94eb6791d49af3 testing commit 2d19be4653f5e74ed95560b69f94eb6791d49af3 with gcc (GCC) 8.4.1 20210217 kernel signature: 4a85d058cc701772a1eb5cfea1b3103e5d7dfd35d9af9bfb9ce9df15433dd654 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: BUG: unable to handle kernel NULL pointer dereference in corrupted 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: BUG: unable to handle kernel NULL pointer dereference in corrupted run #9: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted revisions tested: 2, total time: 24m25.815219117s (build: 16m59.749864055s, test: 6m10.775138696s) the crash still happens on HEAD commit msg: Linux 4.19.177 crash: BUG: unable to handle kernel NULL pointer dereference in corrupted IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready IPv6: ADDRCONF(NETDEV_CHANGE): vxcan1: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): vxcan0: link becomes ready 8021q: adding VLAN 0 to HW filter on device batadv0 ================================================================== BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 BUG: KASAN: null-ptr-deref in memcpy include/linux/string.h:377 [inline] BUG: KASAN: null-ptr-deref in llcp_sock_getname+0x341/0x440 net/nfc/llcp_sock.c:531 PGD 1dcce2067 P4D 1dcce2067 PUD 1dce97067 PMD 0 Read of size 1 at addr 0000000000000000 by task syz-executor.4/6879 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 6877 Comm: syz-executor.2 Not tainted 4.19.177-syzkaller #0 CPU: 0 PID: 6879 Comm: syz-executor.4 Not tainted 4.19.177-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:55 Call Trace: Code: 90 90 90 90 eb 1e 0f 1f 00 48 89 f8 48 89 d1 48 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48 89 d1 a4 c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40 38 fe __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x171 lib/dump_stack.c:118 RSP: 0018:ffff8881db68fcf0 EFLAGS: 00010246 kasan_report_error mm/kasan/report.c:352 [inline] kasan_report mm/kasan/report.c:412 [inline] kasan_report.cold.9+0x6d/0x2fe mm/kasan/report.c:396 RAX: ffff8881db68fe12 RBX: 0000000000000001 RCX: 0000000000000001 RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff8881db68fe12 RBP: ffff8881db68fd10 R08: ffffed103b6d1fc3 R09: ffffed103b6d1fc2 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 R10: ffffed103b6d1fc2 R11: ffff8881db68fe12 R12: ffff8881db68fe12 memcpy+0x23/0x50 mm/kasan/kasan.c:302 R13: 0000000000000000 R14: ffff8881c6dbb580 R15: 0000000000000000 memcpy include/linux/string.h:377 [inline] llcp_sock_getname+0x341/0x440 net/nfc/llcp_sock.c:531 FS: 00007f657e98a700(0000) GS:ffff8881f6900000(0000) knlGS:0000000000000000 __sys_getpeername+0x123/0x220 net/socket.c:1735 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000001ddfe1001 CR4: 00000000001606e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 __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 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 Call Trace: entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x462029 memcpy include/linux/string.h:377 [inline] llcp_sock_getname+0x341/0x440 net/nfc/llcp_sock.c:531 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f96336a71a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000034 __sys_getpeername+0x123/0x220 net/socket.c:1735 RAX: ffffffffffffffda RBX: 000000000052bfa8 RCX: 0000000000462029 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 0000000000000003 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004ed550 R14: 00000000004ad1fd R15: 00007f96336a76bc __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