syzbot


WARNING in fixup_exception

Status: upstream: reported C repro on 2022/01/05 17:07
Reported-by: syzbot+d9a0f6db5058ce56e260@syzkaller.appspotmail.com
First crash: 184d, last: 184d

Cause bisection: failed (bisect log)

Fix bisection: failed (bisect log)

Sample crash report:
------------[ cut here ]------------
General protection fault in user access. Non-canonical address?
WARNING: CPU: 0 PID: 2529 at arch/x86/mm/extable.c:57 ex_handler_uaccess arch/x86/mm/extable.c:57 [inline]
WARNING: CPU: 0 PID: 2529 at arch/x86/mm/extable.c:57 fixup_exception+0x5da/0x690 arch/x86/mm/extable.c:140
Modules linked in:
CPU: 0 PID: 2529 Comm: syz-executor223 Not tainted 5.16.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:ex_handler_uaccess arch/x86/mm/extable.c:57 [inline]
RIP: 0010:fixup_exception+0x5da/0x690 arch/x86/mm/extable.c:140
Code: 0c 31 ff 89 de e8 06 f5 42 00 84 db 0f 85 9b fc ff ff e8 19 f1 42 00 48 c7 c7 20 59 a9 89 c6 05 49 33 48 0c 01 e8 52 cf cb 07 <0f> 0b e9 7c fc ff ff e8 fa f0 42 00 48 89 de 48 c7 c7 c0 59 a9 89
RSP: 0018:ffffc90003bf7bf0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff88801dbd0000 RSI: ffffffff815f0948 RDI: fffff5200077ef70
RBP: ffffffff8b6d0044 R08: 0000000000000000 R09: 0000000000000000
R10: ffffffff815ea6ee R11: 0000000000000000 R12: ffffc90003bf7cc8
R13: 000000000000000d R14: ffffc90003bf7d48 R15: 0000000000000000
FS:  00007f46f7487700(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f46f7d44190 CR3: 0000000022544000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __exc_general_protection arch/x86/kernel/traps.c:601 [inline]
 exc_general_protection+0xed/0x300 arch/x86/kernel/traps.c:562
 asm_exc_general_protection+0x1e/0x30 arch/x86/include/asm/idtentry.h:562
RIP: 0010:__put_user_nocheck_2+0x3/0x11
Code: 00 00 48 39 d9 73 74 0f 01 cb 88 01 31 c9 0f 01 ca c3 66 0f 1f 44 00 00 48 bb ff ef ff ff ff 7f 00 00 48 39 d9 73 54 0f 01 cb <66> 89 01 31 c9 0f 01 ca c3 0f 1f 44 00 00 48 bb fd ef ff ff ff 7f
RSP: 0018:ffffc90003bf7d78 EFLAGS: 00050293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: 0006020200000004
RDX: ffff88801dbd0000 RSI: ffffffff86d1fba8 RDI: 0000000000000003
RBP: ffff888077ff01a8 R08: 0000000000000002 R09: 0000000000000001
R10: ffffffff86d1fb95 R11: 0000000000000000 R12: 0006020200000004
R13: ffff888077ff0258 R14: 0000000000000000 R15: 0000000000000000
 vhost_put_used_flags drivers/vhost/vhost.c:969 [inline]
 vhost_update_used_flags+0x1a3/0x3d0 drivers/vhost/vhost.c:1969
 vhost_vq_init_access+0x114/0x5c0 drivers/vhost/vhost.c:2013
 vhost_net_set_backend drivers/vhost/net.c:1548 [inline]
 vhost_net_ioctl+0xbad/0x1740 drivers/vhost/net.c:1705
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl fs/ioctl.c:860 [inline]
 __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f46f7d02839
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 31 19 00 00 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 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f46f7487208 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f46f7d8a278 RCX: 00007f46f7d02839
RDX: 0000000020000000 RSI: 000000004008af30 RDI: 0000000000000003
RBP: 00007f46f7d8a270 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f46f7d8a27c
R13: 00007ffc8471e10f R14: 00007f46f7487300 R15: 0000000000022000
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	48 39 d9             	cmp    %rbx,%rcx
   5:	73 74                	jae    0x7b
   7:	0f 01 cb             	stac
   a:	88 01                	mov    %al,(%rcx)
   c:	31 c9                	xor    %ecx,%ecx
   e:	0f 01 ca             	clac
  11:	c3                   	retq
  12:	66 0f 1f 44 00 00    	nopw   0x0(%rax,%rax,1)
  18:	48 bb ff ef ff ff ff 	movabs $0x7fffffffefff,%rbx
  1f:	7f 00 00
  22:	48 39 d9             	cmp    %rbx,%rcx
  25:	73 54                	jae    0x7b
  27:	0f 01 cb             	stac
* 2a:	66 89 01             	mov    %ax,(%rcx) <-- trapping instruction
  2d:	31 c9                	xor    %ecx,%ecx
  2f:	0f 01 ca             	clac
  32:	c3                   	retq
  33:	0f 1f 44 00 00       	nopl   0x0(%rax,%rax,1)
  38:	48                   	rex.W
  39:	bb fd ef ff ff       	mov    $0xffffeffd,%ebx
  3e:	ff                   	(bad)
  3f:	7f                   	.byte 0x7f

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce 2022/01/01 17:05 upstream 800829388818 e1768e9c .config log report syz C WARNING in fixup_exception