bisecting fixing commit since 14260788bbb9c94b0e36abc17294266b69dd46e4 building syzkaller on 3a75be00f50996031dd301d44b009d56db3485f0 testing commit 14260788bbb9c94b0e36abc17294266b69dd46e4 with gcc (GCC) 8.1.0 kernel signature: 5dceffe72a82b6855284d106cf787a490fbd3d83e149a84337882049963d02cf 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: 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: BUG: unable to handle kernel NULL pointer dereference in corrupted run #7: crashed: KASAN: null-ptr-deref 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 testing current HEAD ad326970d25cc85128cd22d62398751ad072efff testing commit ad326970d25cc85128cd22d62398751ad072efff with gcc (GCC) 8.1.0 kernel signature: e09d6043a2b56daf2b23cdb1a81f5b997cb312705697f73bd007aa74e6507c2b run #0: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #1: crashed: BUG: unable to handle kernel NULL pointer dereference in corrupted 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: 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: KASAN: null-ptr-deref Read in llcp_sock_getname run #9: crashed: KASAN: null-ptr-deref in llcp_sock_getname revisions tested: 2, total time: 24m8.906465711s (build: 17m34.574877756s, test: 5m47.176531349s) the crash still happens on HEAD commit msg: Linux 4.19.152 crash: KASAN: null-ptr-deref in llcp_sock_getname 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 8021q: adding VLAN 0 to HW filter on device batadv0 ================================================================== 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 BUG: unable to handle kernel NULL pointer dereference at 0000000000000000 Read of size 1 at addr 0000000000000000 by task syz-executor.3/7486 PGD 91cea067 P4D 91cea067 PUD 91ceb067 PMD 0 Oops: 0000 [#1] PREEMPT SMP KASAN CPU: 1 PID: 7486 Comm: syz-executor.3 Not tainted 4.19.152-syzkaller #0 CPU: 0 PID: 7489 Comm: syz-executor.1 Not tainted 4.19.152-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 Call Trace: RIP: 0010:memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:55 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x123/0x177 lib/dump_stack.c:118 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 kasan_report_error mm/kasan/report.c:352 [inline] kasan_report.cold.9+0x6d/0x309 mm/kasan/report.c:412 RSP: 0018:ffff88809259fcf0 EFLAGS: 00010246 RAX: ffff88809259fe12 RBX: 0000000000000001 RCX: 0000000000000001 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 RDX: 0000000000000001 RSI: 0000000000000000 RDI: ffff88809259fe12 memcpy+0x23/0x50 mm/kasan/kasan.c:302 RBP: ffff88809259fd10 R08: ffffed10124b3fc3 R09: ffffed10124b3fc2 memcpy include/linux/string.h:373 [inline] llcp_sock_getname+0x341/0x440 net/nfc/llcp_sock.c:531 R10: ffffed10124b3fc2 R11: ffff88809259fe12 R12: ffff88809259fe12 R13: 0000000000000000 R14: ffff88808052e5c0 R15: 0000000000000000 __sys_getpeername+0x123/0x220 net/socket.c:1735 FS: 00007f3fce569700(0000) GS:ffff8880ba600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 0000000091ce9000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: memcpy include/linux/string.h:373 [inline] llcp_sock_getname+0x341/0x440 net/nfc/llcp_sock.c:531 __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 __sys_getpeername+0x123/0x220 net/socket.c:1735 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x45a6f9 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:00007f806ab97c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000034 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a6f9 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004 __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 RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f806ab986d4 entry_SYSCALL_64_after_hwframe+0x49/0xbe R13: 00000000004c1480 R14: 00000000004d4a50 R15: 00000000ffffffff ================================================================== RIP: 0033:0x45a6f9