bisecting fixing commit since b98aebd298246df37b472c52a2ee1023256d02e3 building syzkaller on 04ca72cd45348daab9d896bbec8ea4c2d13455ac testing commit b98aebd298246df37b472c52a2ee1023256d02e3 with gcc (GCC) 8.1.0 kernel signature: efa085747c59a8ef754da18f692564f621f80f9d4a179022818c1c29b987f99c run #0: crashed: KASAN: null-ptr-deref 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: BUG: unable to handle kernel run #5: crashed: BUG: unable to handle kernel 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 testing current HEAD 4520f06b03ae667e442da1ab9351fd28cd7ac598 testing commit 4520f06b03ae667e442da1ab9351fd28cd7ac598 with gcc (GCC) 8.1.0 kernel signature: 683f0f58ddb1a7958782871595e579304e2bb7e95e5bab8b8086fe67aec025b3 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 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: BUG: unable to handle kernel NULL pointer dereference in corrupted run #7: crashed: KASAN: null-ptr-deref Read in llcp_sock_getname run #8: crashed: BUG: unable to handle kernel run #9: crashed: BUG: unable to handle kernel revisions tested: 2, total time: 23m31.528718332s (build: 16m55.36109715s, test: 6m4.060529758s) the crash still happens on HEAD commit msg: Linux 4.14.175 crash: BUG: unable to handle kernel IPv6: ADDRCONF(NETDEV_CHANGE): hsr_slave_1: link becomes ready IPv6: ADDRCONF(NETDEV_UP): vxcan1: link is not ready 8021q: adding VLAN 0 to HW filter on device batadv0 8021q: adding VLAN 0 to HW filter on device batadv0 ================================================================== BUG: unable to handle kernel 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 NULL pointer dereference at (null) Read of size 63 at addr (null) by task syz-executor.0/7238 IP: memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54 PGD 8e965067 CPU: 0 PID: 7238 Comm: syz-executor.0 Not tainted 4.14.175-syzkaller #0 P4D 8e965067 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: PUD 8e966067 __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xf7/0x13b lib/dump_stack.c:58 PMD 0 kasan_report_error mm/kasan/report.c:349 [inline] kasan_report.cold.8+0x6d/0x2d3 mm/kasan/report.c:409 Oops: 0000 [#1] PREEMPT SMP KASAN check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 Modules linked in: memcpy+0x23/0x50 mm/kasan/kasan.c:302 memcpy include/linux/string.h:347 [inline] llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532 CPU: 1 PID: 7240 Comm: syz-executor.3 Not tainted 4.14.175-syzkaller #0 sock_getsockopt+0xaf4/0x1921 net/core/sock.c:1276 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880a08a4140 task.stack: ffff888082ef8000 RIP: 0010:memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54 RSP: 0018:ffff888082effb10 EFLAGS: 00010246 RAX: ffff888082effd42 RBX: 000000000000003f RCX: 000000000000003f RDX: 000000000000003f RSI: 0000000000000000 RDI: ffff888082effd42 RBP: ffff888082effb30 R08: ffffed10105dffb1 R09: ffffed10105dffa8 R10: ffffed10105dffb0 R11: ffff888082effd80 R12: ffff888082effd42 R13: 0000000000000000 R14: ffff8880a08fce10 R15: ffff8880a08fc9c0 SYSC_getsockopt net/socket.c:1892 [inline] SyS_getsockopt+0x1b6/0x1e0 net/socket.c:1878 FS: 00007ff51fc15700(0000) GS:ffff8880aef00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 000000008e964000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 memcpy include/linux/string.h:347 [inline] llcp_sock_getname+0x378/0x480 net/nfc/llcp_sock.c:532 sock_getsockopt+0xaf4/0x1921 net/core/sock.c:1276 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x459f39 RSP: 002b:00007f6bd9dddc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459f39 RDX: 000000000000001c RSI: 0000000000000001 RDI: 0000000000000004 RBP: 000000000075bf20 R08: 0000000020000140 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6bd9dde6d4 R13: 00000000004c1408 R14: 00000000004d4ae0 R15: 00000000ffffffff ================================================================== SYSC_getsockopt net/socket.c:1892 [inline] SyS_getsockopt+0x1b6/0x1e0 net/socket.c:1878 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x459f39 RSP: 002b:00007ff51fc14c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000037 RAX: ffffffffffffffda RBX: 0000000000000005 RCX: 0000000000459f39 RDX: 000000000000001c RSI: 0000000000000001 RDI: 0000000000000004 RBP: 000000000075bfc8 R08: 0000000020000140 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff51fc156d4 R13: 00000000004c1408 R14: 00000000004d4ae0 R15: 00000000ffffffff Code: 90 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 RIP: memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54 RSP: ffff888082effb10 CR2: 0000000000000000 BUG: unable to handle kernel NULL pointer dereference at (null) IP: memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54 PGD 8d9ce067 P4D 8d9ce067 PUD 8e041067 PMD 0 Oops: 0000 [#2] PREEMPT SMP KASAN Modules linked in: CPU: 0 PID: 7239 Comm: syz-executor.5 Tainted: G B D 4.14.175-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880a0194100 task.stack: ffff888082f40000 RIP: 0010:memcpy_erms+0x6/0x10 arch/x86/lib/memcpy_64.S:54 RSP: 0018:ffff888082f47b10 EFLAGS: 00010246 RAX: ffff888082f47d42 RBX: 000000000000003f RCX: 000000000000003f RDX: 000000000000003f RSI: 0000000000000000 RDI: ffff888082f47d42 RBP: ffff888082f47b30 R08: ffffed10105e8fb1 R09: ffffed10105e8fa8 R10: ffffed10105e8fb0 R11: ffff888082f47d80 R12: ffff888082f47d42 R13: 0000000000000000 R14: ffff8880964e99d0 R15: ffff8880964e9580