Re: general protection fault in lockdep_invariant_state (2)

[Eric Biggers]

On Wed, Nov 08, 2017 at 12:16:00AM -0800, syzbot wrote:
> Hello,
> 
> syzkaller hit the following crash on
> 5a3517e009e979f21977d362212b7729c5165d92
> git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> C reproducer is attached
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers
> 
> 
> R13: 0000000000402260 R14: 00000000004022f0 R15: 0000000000000000
> kasan: CONFIG_KASAN_INLINE enabled
> kasan: GPF could be caused by NULL-ptr deref or user memory access
> general protection fault: 0000 [#1] SMP KASAN
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Modules linked in:
> CPU: 3 PID: 2982 Comm: syzkaller521009 Not tainted 4.14.0-rc7-next-20171103+
> #10
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
> task: ffff88003d6b25c0 task.stack: ffff88003abd0000
> RIP: 0010:invalidate_xhlock kernel/locking/lockdep.c:4719 [inline]
> RIP: 0010:lockdep_invariant_state+0xd6/0x120 kernel/locking/lockdep.c:4793
> RSP: 0018:ffff88003abd7e38 EFLAGS: 00010002
> RAX: dffffc0000000000 RBX: 0000000000001d88 RCX: ffffffff81008d3f
> RDX: 00000000000003bc RSI: 0000000000000000 RDI: 0000000000001de0
> RBP: ffff88003abd7e48 R08: ffffffff85f3b680 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: ffff88003abd7ee0 R14: ffff88003d6b25c0 R15: ffffffff85ecb390
> FS:  0000000002024880(0000) GS:ffff88006df00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00005585762cd008 CR3: 000000003a704000 CR4: 00000000000006e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  lockdep_sys_exit+0x47/0xf0 kernel/locking/lockdep.c:4629
>  prepare_exit_to_usermode arch/x86/entry/common.c:192 [inline]
>  syscall_return_slowpath+0x244/0x510 arch/x86/entry/common.c:266
>  ret_from_fork+0x15/0x40 arch/x86/entry/entry_64.S:424
> RIP: 0033:0x4358a9
> RSP: 002b:0000000020218fa0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
> RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00000000004358a9
> RDX: 0000000020acc000 RSI: 0000000020218fa0 RDI: 0000000000000000
> RBP: 0000000000000000 R08: 00000000201fa000 R09: 0000000000000000
> R10: 000000002097b000 R11: 0000000000000246 R12: 0000000000000001
> R13: 0000000000402260 R14: 00000000004022f0 R15: 0000000000000000
> Code: 83 90 11 00 00 83 e0 3f 48 89 c2 48 c1 e2 04 48 29 c2 48 b8 00 00 00
> 00 00 fc ff df 49 8d 1c d4 48 8d 7b 58 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75
> 2f 48 c7 43 58 00 00 00 00 5b 41 5c 5d c3 0f ff
> RIP: invalidate_xhlock kernel/locking/lockdep.c:4719 [inline] RSP:
> ffff88003abd7e38
> RIP: lockdep_invariant_state+0xd6/0x120 kernel/locking/lockdep.c:4793 RSP:
> ffff88003abd7e38
> ---[ end trace b75e41873a1a07c3 ]---
> Kernel panic - not syncing: Fatal exception
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
> 
> 
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzkaller@xxxxxxxxxxxxxxxxx
> Please credit me with: Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
> 
> syzbot will keep track of this bug report.
> Once a fix for this bug is committed, please reply to this email with:
> #syz fix: exact-commit-title

No longer occurring, seems to have been fixed by:

#syz fix: locking/lockdep: Fix possible NULL deref