Re: 2.6.15-rc1-mm1

[Andrew Morton <akpm@osdl.org>]

Reuben Farrelly <reuben-lkml@reub.net> wrote:
>
> I don't think I should be able to make this happen so easily though:
> 
> 
>  [root@tornado ~]# rmmod e100
>  [root@tornado ~]# rmmod sky2
>  [root@tornado ~]# strace modprobe e100
>  Unable to handle kernel NULL pointer dereference at virtual address 00000010
>    printing eip:
>  c0124fc7
>  *pde = 00000000
>  Oops: 0000 [#1]
>  PREEMPT SMP
>  last sysfs file: /class/net/eth0/flags
>  Modules linked in: nfsd exportfs lockd sunrpc autofs4 lm85 hwmon_vid eeprom ipv6 
>  binfmt_misc hw_random crc32 piix i2c_i801
>  CPU:    0
>  EIP:    0060:[<c0124fc7>]    Not tainted VLI
>  EFLAGS: 00010202   (2.6.15-rc1-mm2-preempt)
>  EIP is at ptrace_check_attach+0x14/0xaf


This might help..


Begin forwarded message:

Date: Fri, 18 Nov 2005 18:07:43 +0000
From: Christoph Hellwig <hch@infradead.org>
To: Badari Pulavarty <pbadari@us.ibm.com>
Cc: akpm@osdl.org, lkml <linux-kernel@vger.kernel.org>
Subject: Re: 2.6.15-rc1-mm1 panic in ptrace_check_attach()


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