2.6.15-rc1-mm1 panic in ptrace_check_attach()

2.6.15-rc1-mm1 panic in ptrace_check_attach()

[Badari Pulavarty]

Hi Andrew,

I am not sure if its already reported. I get panic in
ptrace_check_attach() while trying to run UML on 2.6.15-rc1-mm1.

Going to try 2.6.15-rc1-mm2 now. 

Thanks,
Badari

Unable to handle kernel NULL pointer dereference at 0000000000000020
RIP:
<ffffffff8013d834>{ptrace_check_attach+36}
PGD 1ccc6c067 PUD 1ce816067 PMD 0
Oops: 0000 [2] SMP
CPU 3
Modules linked in: floppy thermal processor fan button battery ac
parport_pc lp parport evdev joydev st sr_mod ipv6 sg qla2300 qlogicfc
qla2200 qla2xxx firmware_class ohci_hcd hw_random usbcore dm_mod
Pid: 21537, comm: linux Not tainted 2.6.15-rc1-mm1 #1
RIP: 0010:[<ffffffff8013d834>] <ffffffff8013d834>{ptrace_check_attach
+36}
RSP: 0018:ffff810195c75ef8  EFLAGS: 00010216
RAX: ffffffff805d2080 RBX: 0000000000000000 RCX: ffff8101cc69d228
RDX: ffff8101cc69d220 RSI: 0000000000000000 RDI: ffffffff805d2080
RBP: 0000000000000000 R08: 0000000055681c58 R09: 00000000ffffbc78
R10: ffff810195c74000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000001 R14: 0000000000000000 R15: 0000000000000000
FS:  00002aaaab2890a0(0000) GS:ffffffff805cc180(0063)
knlGS:0000000055685080
CS:  0010 DS: 002b ES: 002b CR0: 000000008005003b
CR2: 0000000000000020 CR3: 00000001ca93e000 CR4: 00000000000006e0
Process linux (pid: 21537, threadinfo ffff810195c74000, task
ffff81019d031110)
Stack: 0000000000000000 0000000000000000 0000000000000015
ffffffff8013d96a
       0000000000000015 0000000000000001 0000000000000000
0000000000000000
       0000000000000000 ffffffff8012a75f
Call Trace:<ffffffff8013d96a>{sys_ptrace+122}
<ffffffff8012a75f>{sys32_ptrace+111}
       <ffffffff8011f453>{cstar_do_call+27}

Code: f6 43 20 01 bd fd ff ff ff 0f 84 81 00 00 00 65 48 8b 04 25
RIP <ffffffff8013d834>{ptrace_check_attach+36} RSP <ffff810195c75ef8>
CR2: 0000000000000020
 NMI Watchdog detected LOCKUP on CPU 3
CPU 3
Modules linked in: floppy thermal processor fan button battery ac
parport_pc lp parport evdev joydev st sr_mod ipv6 sg qla2300 qlogicfc
qla2200 qla2xxx firmware_class ohci_hcd hw_random usbcore dm_mod
Pid: 21537, comm: linux Not tainted 2.6.15-rc1-mm1 #1
RIP: 0010:[<ffffffff802a79c3>] <ffffffff802a79c3>{__write_lock_failed
+15}
RSP: 0018:ffff810195c75cc8  EFLAGS: 00000087
RAX: ffffffff805d2080 RBX: ffff81017fc3cb40 RCX: 0000000000000079
RDX: ffff81019d0312a0 RSI: 0000000000000296 RDI: ffffffff805d2080
RBP: ffff81019d031110 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 00ff00ff00ff00ff R12: ffff81019d031754
R13: ffff81019d031110 R14: ffff810195c75cf8 R15: ffff810195c75e48
FS:  00002aaaab2890a0(0000) GS:ffffffff805cc180(0000)
knlGS:0000000055685080
CS:  0010 DS: 002b ES: 002b CR0: 000000008005003b
CR2: 0000000000000020 CR3: 0000000000101000 CR4: 00000000000006e0
Process linux (pid: 21537, threadinfo ffff810195c74000, task
ffff81019d031110)
Stack: ffffffff803fcc88 ffffffff80137fec ffff81019d0312a0
ffffffff80499ec8
       ffffffff80499ec8 0000000000000246 ffffffff8048faac
ffffffffffffffef
       ffffffff803fcaf8 0000000000000246
Call Trace:<ffffffff803fcc88>{.text.lock.spinlock+79}
<ffffffff80137fec>{do_exit+1212}
       <ffffffff803fcaf8>{_spin_unlock_irqrestore+8}
<ffffffff803fe5f5>{do_page_fault+1925}
       <ffffffff8015b821>{filemap_nopage+385}
<ffffffff8016a1d5>{__handle_mm_fault+1941}
       <ffffffff801379ca>{do_wait+2938} <ffffffff8010ec1d>{error_exit+0}
       <ffffffff8013d834>{ptrace_check_attach+36}
<ffffffff8013d834>{ptrace_check_attach+36}
       <ffffffff8013d96a>{sys_ptrace+122}
<ffffffff8012a75f>{sys32_ptrace+111}
       <ffffffff8011f453>{cstar_do_call+27}

Code: 75 f6 f0 81 28 00 00 00 01 0f 85 e2 ff ff ff c3 90 f0 ff 00
console shuts up ...
 <0>Kernel panic - not syncing: Aiee, killing interrupt handler!

Re: 2.6.15-rc1-mm1 panic in ptrace_check_attach()

[Christoph Hellwig]

On Fri, Nov 18, 2005 at 09:56:40AM -0800, Badari Pulavarty wrote:
> Hi Andrew,
> 
> I am not sure if its already reported. I get panic in
> ptrace_check_attach() while trying to run UML on 2.6.15-rc1-mm1.
> 
> Going to try 2.6.15-rc1-mm2 now. 

Looks like 2.6.15-rc1-mm1 has total crap in ptrace_get_task_struct
(and it looks like my fault because I sent out a wrong patch).

The patch below should fix it:

Index: linux-2.6/kernel/ptrace.c
===================================================================
--- linux-2.6.orig/kernel/ptrace.c	2005-11-18 10:25:35.000000000 +0100
+++ linux-2.6/kernel/ptrace.c	2005-11-18 10:25:54.000000000 +0100
@@ -459,7 +459,7 @@
 	read_unlock(&tasklist_lock);
 	if (!child)
 		return ERR_PTR(-ESRCH);
-	return 0;
+	return child;
 }
 
 #ifndef __ARCH_SYS_PTRACE

Re: 2.6.15-rc1-mm1 panic in ptrace_check_attach()

[Badari Pulavarty]

On Fri, 2005-11-18 at 18:07 +0000, Christoph Hellwig wrote:
> On Fri, Nov 18, 2005 at 09:56:40AM -0800, Badari Pulavarty wrote:
> > Hi Andrew,
> > 
> > I am not sure if its already reported. I get panic in
> > ptrace_check_attach() while trying to run UML on 2.6.15-rc1-mm1.
> > 
> > Going to try 2.6.15-rc1-mm2 now. 
> 
> Looks like 2.6.15-rc1-mm1 has total crap in ptrace_get_task_struct
> (and it looks like my fault because I sent out a wrong patch).
> 
> The patch below should fix it:
> 
> Index: linux-2.6/kernel/ptrace.c
> ===================================================================
> --- linux-2.6.orig/kernel/ptrace.c	2005-11-18 10:25:35.000000000 +0100
> +++ linux-2.6/kernel/ptrace.c	2005-11-18 10:25:54.000000000 +0100
> @@ -459,7 +459,7 @@
>  	read_unlock(&tasklist_lock);
>  	if (!child)
>  		return ERR_PTR(-ESRCH);
> -	return 0;
> +	return child;
>  }
>  
>  #ifndef __ARCH_SYS_PTRACE
> 

Fixed the problem. I guess we need this for 2.6.15-rc1-mm2 also.

Thanks,
Badari