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* WARNING: can't access registers at asm_sysvec_call_function_single
@ 2020-09-08 20:16 syzbot
  2020-09-13 21:05 ` Thomas Gleixner
  0 siblings, 1 reply; 6+ messages in thread
From: syzbot @ 2020-09-08 20:16 UTC (permalink / raw)
  To: alexandre.chartre, bp, hpa, linux-kernel, luto, mingo, peterz,
	syzkaller-bugs, tglx, x86

Hello,

syzbot found the following issue on:

HEAD commit:    f4d51dff Linux 5.9-rc4
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1455d4f9900000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9
dashboard link: https://syzkaller.appspot.com/bug?extid=bc9dbf05dcc151e9b972
compiler:       gcc (GCC) 10.1.0-syz 20200507

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bc9dbf05dcc151e9b972@syzkaller.appspotmail.com

WARNING: can't access registers at asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:589


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: WARNING: can't access registers at asm_sysvec_call_function_single
  2020-09-08 20:16 WARNING: can't access registers at asm_sysvec_call_function_single syzbot
@ 2020-09-13 21:05 ` Thomas Gleixner
  2020-09-14 16:49   ` Josh Poimboeuf
  0 siblings, 1 reply; 6+ messages in thread
From: Thomas Gleixner @ 2020-09-13 21:05 UTC (permalink / raw)
  To: syzbot, alexandre.chartre, bp, hpa, linux-kernel, luto, mingo,
	peterz, syzkaller-bugs, x86, Josh Poimboeuf

On Tue, Sep 08 2020 at 13:16, syzbot wrote:

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    f4d51dff Linux 5.9-rc4
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1455d4f9900000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9
> dashboard link: https://syzkaller.appspot.com/bug?extid=bc9dbf05dcc151e9b972
> compiler:       gcc (GCC) 10.1.0-syz 20200507
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+bc9dbf05dcc151e9b972@syzkaller.appspotmail.com
>
> WARNING: can't access registers at asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:589

That's the ORC unwinder complaining, but I have no idea why...

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: WARNING: can't access registers at asm_sysvec_call_function_single
  2020-09-13 21:05 ` Thomas Gleixner
@ 2020-09-14 16:49   ` Josh Poimboeuf
  2020-09-14 16:51     ` Josh Poimboeuf
  0 siblings, 1 reply; 6+ messages in thread
From: Josh Poimboeuf @ 2020-09-14 16:49 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: syzbot, alexandre.chartre, bp, hpa, linux-kernel, luto, mingo,
	peterz, syzkaller-bugs, x86

On Sun, Sep 13, 2020 at 11:05:21PM +0200, Thomas Gleixner wrote:
> On Tue, Sep 08 2020 at 13:16, syzbot wrote:
> 
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    f4d51dff Linux 5.9-rc4
> > git tree:       upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=1455d4f9900000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9
> > dashboard link: https://syzkaller.appspot.com/bug?extid=bc9dbf05dcc151e9b972
> > compiler:       gcc (GCC) 10.1.0-syz 20200507
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+bc9dbf05dcc151e9b972@syzkaller.appspotmail.com
> >
> > WARNING: can't access registers at asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:589
> 
> That's the ORC unwinder complaining, but I have no idea why...

0000000000000cd0 <asm_sysvec_call_function_single>:
     cd0:	90                   	nop
     cd1:	90                   	nop
     cd2:	90                   	nop
     cd3:	6a ff                	pushq  $0xffffffffffffffff
     cd5:	e8 b6 03 00 00       	callq  1090 <error_entry>
     cda:	48 89 e7             	mov    %rsp,%rdi
     cdd:	e8 00 00 00 00       	callq  ce2 <asm_sysvec_call_function_single+0x12>
			cde: R_X86_64_PLT32	sysvec_call_function_single-0x4
     ce2:	e9 69 04 00 00       	jmpq   1150 <error_return>
     ce7:	66 0f 1f 84 00 00 00 	nopw   0x0(%rax,%rax,1)
     cee:	00 00

This is a head scratcher.  The ORC data looks ok, at least when I build
it on my system.  It's expecting to find pt_regs at the top of the stack
after returning from sysvec_call_function_single().  But it can't
dereference the regs for some reason.

So either it's a bug in ORC data or unwinder (not likely) or the stack
pointer got corrupted somehow (also seems unlikely)...

-- 
Josh


^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: WARNING: can't access registers at asm_sysvec_call_function_single
  2020-09-14 16:49   ` Josh Poimboeuf
@ 2020-09-14 16:51     ` Josh Poimboeuf
  2020-09-15  4:27       ` Dmitry Vyukov
  0 siblings, 1 reply; 6+ messages in thread
From: Josh Poimboeuf @ 2020-09-14 16:51 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: syzbot, alexandre.chartre, bp, hpa, linux-kernel, luto, mingo,
	peterz, syzkaller-bugs, x86

On Mon, Sep 14, 2020 at 11:49:30AM -0500, Josh Poimboeuf wrote:
> On Sun, Sep 13, 2020 at 11:05:21PM +0200, Thomas Gleixner wrote:
> > On Tue, Sep 08 2020 at 13:16, syzbot wrote:
> > 
> > > Hello,
> > >
> > > syzbot found the following issue on:
> > >
> > > HEAD commit:    f4d51dff Linux 5.9-rc4
> > > git tree:       upstream
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=1455d4f9900000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=bc9dbf05dcc151e9b972
> > > compiler:       gcc (GCC) 10.1.0-syz 20200507
> > >
> > > Unfortunately, I don't have any reproducer for this issue yet.
> > >
> > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > Reported-by: syzbot+bc9dbf05dcc151e9b972@syzkaller.appspotmail.com
> > >
> > > WARNING: can't access registers at asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:589
> > 
> > That's the ORC unwinder complaining, but I have no idea why...
> 
> 0000000000000cd0 <asm_sysvec_call_function_single>:
>      cd0:	90                   	nop
>      cd1:	90                   	nop
>      cd2:	90                   	nop
>      cd3:	6a ff                	pushq  $0xffffffffffffffff
>      cd5:	e8 b6 03 00 00       	callq  1090 <error_entry>
>      cda:	48 89 e7             	mov    %rsp,%rdi
>      cdd:	e8 00 00 00 00       	callq  ce2 <asm_sysvec_call_function_single+0x12>
> 			cde: R_X86_64_PLT32	sysvec_call_function_single-0x4
>      ce2:	e9 69 04 00 00       	jmpq   1150 <error_return>
>      ce7:	66 0f 1f 84 00 00 00 	nopw   0x0(%rax,%rax,1)
>      cee:	00 00
> 
> This is a head scratcher.  The ORC data looks ok, at least when I build
> it on my system.  It's expecting to find pt_regs at the top of the stack
> after returning from sysvec_call_function_single().  But it can't
> dereference the regs for some reason.
> 
> So either it's a bug in ORC data or unwinder (not likely) or the stack
> pointer got corrupted somehow (also seems unlikely)...

The true bug may be revealed elsewhere on the stack... I probably need
to start enabling ORC stack dumps like I did for FP.

-- 
Josh


^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: WARNING: can't access registers at asm_sysvec_call_function_single
  2020-09-14 16:51     ` Josh Poimboeuf
@ 2020-09-15  4:27       ` Dmitry Vyukov
  2020-09-15 14:19         ` Josh Poimboeuf
  0 siblings, 1 reply; 6+ messages in thread
From: Dmitry Vyukov @ 2020-09-15  4:27 UTC (permalink / raw)
  To: Josh Poimboeuf
  Cc: Thomas Gleixner, syzbot, alexandre.chartre, Borislav Petkov,
	H. Peter Anvin, LKML, Andy Lutomirski, Ingo Molnar,
	Peter Zijlstra, syzkaller-bugs, the arch/x86 maintainers

On Mon, Sep 14, 2020 at 6:51 PM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > > On Tue, Sep 08 2020 at 13:16, syzbot wrote:
> > >
> > > > Hello,
> > > >
> > > > syzbot found the following issue on:
> > > >
> > > > HEAD commit:    f4d51dff Linux 5.9-rc4
> > > > git tree:       upstream
> > > > console output: https://syzkaller.appspot.com/x/log.txt?x=1455d4f9900000
> > > > kernel config:  https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9
> > > > dashboard link: https://syzkaller.appspot.com/bug?extid=bc9dbf05dcc151e9b972
> > > > compiler:       gcc (GCC) 10.1.0-syz 20200507
> > > >
> > > > Unfortunately, I don't have any reproducer for this issue yet.
> > > >
> > > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > > Reported-by: syzbot+bc9dbf05dcc151e9b972@syzkaller.appspotmail.com
> > > >
> > > > WARNING: can't access registers at asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:589
> > >
> > > That's the ORC unwinder complaining, but I have no idea why...
> >
> > 0000000000000cd0 <asm_sysvec_call_function_single>:
> >      cd0:     90                      nop
> >      cd1:     90                      nop
> >      cd2:     90                      nop
> >      cd3:     6a ff                   pushq  $0xffffffffffffffff
> >      cd5:     e8 b6 03 00 00          callq  1090 <error_entry>
> >      cda:     48 89 e7                mov    %rsp,%rdi
> >      cdd:     e8 00 00 00 00          callq  ce2 <asm_sysvec_call_function_single+0x12>
> >                       cde: R_X86_64_PLT32     sysvec_call_function_single-0x4
> >      ce2:     e9 69 04 00 00          jmpq   1150 <error_return>
> >      ce7:     66 0f 1f 84 00 00 00    nopw   0x0(%rax,%rax,1)
> >      cee:     00 00
> >
> > This is a head scratcher.  The ORC data looks ok, at least when I build
> > it on my system.  It's expecting to find pt_regs at the top of the stack
> > after returning from sysvec_call_function_single().  But it can't
> > dereference the regs for some reason.
> >
> > So either it's a bug in ORC data or unwinder (not likely) or the stack
> > pointer got corrupted somehow (also seems unlikely)...
>
> The true bug may be revealed elsewhere on the stack... I probably need
> to start enabling ORC stack dumps like I did for FP.

Hi Josh,

Is there a config for this? We could enable it on syzbot. More
informative kernel diagnostics are always better.

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: WARNING: can't access registers at asm_sysvec_call_function_single
  2020-09-15  4:27       ` Dmitry Vyukov
@ 2020-09-15 14:19         ` Josh Poimboeuf
  0 siblings, 0 replies; 6+ messages in thread
From: Josh Poimboeuf @ 2020-09-15 14:19 UTC (permalink / raw)
  To: Dmitry Vyukov
  Cc: Thomas Gleixner, syzbot, alexandre.chartre, Borislav Petkov,
	H. Peter Anvin, LKML, Andy Lutomirski, Ingo Molnar,
	Peter Zijlstra, syzkaller-bugs, the arch/x86 maintainers

On Tue, Sep 15, 2020 at 06:27:25AM +0200, Dmitry Vyukov wrote:
> On Mon, Sep 14, 2020 at 6:51 PM Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > > > On Tue, Sep 08 2020 at 13:16, syzbot wrote:
> > > >
> > > > > Hello,
> > > > >
> > > > > syzbot found the following issue on:
> > > > >
> > > > > HEAD commit:    f4d51dff Linux 5.9-rc4
> > > > > git tree:       upstream
> > > > > console output: https://syzkaller.appspot.com/x/log.txt?x=1455d4f9900000
> > > > > kernel config:  https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9
> > > > > dashboard link: https://syzkaller.appspot.com/bug?extid=bc9dbf05dcc151e9b972
> > > > > compiler:       gcc (GCC) 10.1.0-syz 20200507
> > > > >
> > > > > Unfortunately, I don't have any reproducer for this issue yet.
> > > > >
> > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > > > > Reported-by: syzbot+bc9dbf05dcc151e9b972@syzkaller.appspotmail.com
> > > > >
> > > > > WARNING: can't access registers at asm_sysvec_call_function_single+0x12/0x20 arch/x86/include/asm/idtentry.h:589
> > > >
> > > > That's the ORC unwinder complaining, but I have no idea why...
> > >
> > > 0000000000000cd0 <asm_sysvec_call_function_single>:
> > >      cd0:     90                      nop
> > >      cd1:     90                      nop
> > >      cd2:     90                      nop
> > >      cd3:     6a ff                   pushq  $0xffffffffffffffff
> > >      cd5:     e8 b6 03 00 00          callq  1090 <error_entry>
> > >      cda:     48 89 e7                mov    %rsp,%rdi
> > >      cdd:     e8 00 00 00 00          callq  ce2 <asm_sysvec_call_function_single+0x12>
> > >                       cde: R_X86_64_PLT32     sysvec_call_function_single-0x4
> > >      ce2:     e9 69 04 00 00          jmpq   1150 <error_return>
> > >      ce7:     66 0f 1f 84 00 00 00    nopw   0x0(%rax,%rax,1)
> > >      cee:     00 00
> > >
> > > This is a head scratcher.  The ORC data looks ok, at least when I build
> > > it on my system.  It's expecting to find pt_regs at the top of the stack
> > > after returning from sysvec_call_function_single().  But it can't
> > > dereference the regs for some reason.
> > >
> > > So either it's a bug in ORC data or unwinder (not likely) or the stack
> > > pointer got corrupted somehow (also seems unlikely)...
> >
> > The true bug may be revealed elsewhere on the stack... I probably need
> > to start enabling ORC stack dumps like I did for FP.
> 
> Hi Josh,
> 
> Is there a config for this? We could enable it on syzbot. More
> informative kernel diagnostics are always better.

Unfortunately the ORC dump code doesn't exist upstream yet.  I need to
dust the patches off and post.

-- 
Josh


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-09-16  0:17 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-09-08 20:16 WARNING: can't access registers at asm_sysvec_call_function_single syzbot
2020-09-13 21:05 ` Thomas Gleixner
2020-09-14 16:49   ` Josh Poimboeuf
2020-09-14 16:51     ` Josh Poimboeuf
2020-09-15  4:27       ` Dmitry Vyukov
2020-09-15 14:19         ` Josh Poimboeuf

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