kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 9656 Comm: syz-executor.2 Not tainted 4.14.278-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff8880abbc86c0 task.stack: ffff8880b3b50000
RIP: 0010:vgem_fence_attach_ioctl+0x2f8/0x6e0 drivers/gpu/drm/vgem/vgem_fence.c:184
RSP: 0018:ffff8880b3b57bb0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8880b3b57cd0 RCX: ffffc90008000000
RDX: 000000000000001c RSI: ffffffff8148984c RDI: 00000000000000e0
RBP: ffff8880ae7cdac0 R08: ffffffff8c0af608 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880aba9e780
R13: 1ffff1101676af78 R14: ffff8880b3b57cd4 R15: 0000000000000000
FS:  00007f4490390700(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055e8f9c44fc7 CR3: 00000000a9839000 CR4: 00000000003406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 drm_ioctl_kernel+0x14c/0x200 drivers/gpu/drm/drm_ioctl.c:737
 drm_ioctl+0x42e/0x890 drivers/gpu/drm/drm_ioctl.c:840
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f4491a1b0e9
RSP: 002b:00007f4490390168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f4491b2df60 RCX: 00007f4491a1b0e9
RDX: 0000000020000040 RSI: 00000000c0106441 RDI: 0000000000000003
RBP: 00007f4491a7508d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fffd18c623f R14: 00007f4490390300 R15: 0000000000022000
Code: ea 03 80 3c 02 00 0f 85 a2 03 00 00 4c 8b bd 18 01 00 00 48 b8 00 00 00 00 00 fc ff df 49 8d bf e0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 86 03 00 00 4c 89 f2 4d 8b bf e0 00 00 00 48 
RIP: vgem_fence_attach_ioctl+0x2f8/0x6e0 drivers/gpu/drm/vgem/vgem_fence.c:184 RSP: ffff8880b3b57bb0
netlink: 48 bytes leftover after parsing attributes in process `syz-executor.0'.
device batadv1 entered promiscuous mode
8021q: adding VLAN 0 to HW filter on device batadv1
---[ end trace 23a43595edea11fe ]---
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	03 80 3c 02 00 0f    	add    0xf00023c(%rax),%eax
   6:	85 a2 03 00 00 4c    	test   %esp,0x4c000003(%rdx)
   c:	8b bd 18 01 00 00    	mov    0x118(%rbp),%edi
  12:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  19:	fc ff df
  1c:	49 8d bf e0 00 00 00 	lea    0xe0(%r15),%rdi
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:	0f 85 86 03 00 00    	jne    0x3ba
  34:	4c 89 f2             	mov    %r14,%rdx
  37:	4d 8b bf e0 00 00 00 	mov    0xe0(%r15),%r15
  3e:	48                   	rex.W