linux-kernel - Re: 2.6.37-rc7: Regression: b43: crashes in hwrng

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Date:	Thu, 30 Dec 2010 15:34:06 +0100
From:	"Mario 'BitKoenig' Holbe" <Mario.Holbe@...Ilmenau.DE>
To:	Larry Finger <Larry.Finger@...inger.net>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	wireless <linux-wireless@...r.kernel.org>,
	b43-dev <b43-dev@...ts.infradead.org>
Subject: Re: 2.6.37-rc7: Regression: b43: crashes in hwrng_register()

On Wed, Dec 29, 2010 at 08:37:10PM -0600, Larry Finger wrote:
> No, don't bother. I do have a different request. The byte counts for my 32-bit
> system do not match yours. Could you please use the following command to find
> the instructions that are failing?
> 
> objdump -l -d drivers/char/hw_random/core.o | less
> 
> Use the search to find the start of hwrng_register, then add 0x4c to the
> starting address. Once I see hte instruction that is failing, I should be able
> to find where the failure occurs.

Alright, here we go...

[   30.012695] BUG: unable to handle kernel paging request at 4b28f458
[   30.012708] IP: [<f90703cc>] hwrng_register+0x4c/0x139 [rng_core]

00000380 <hwrng_register>:
hwrng_register():
/tmp/1/linux-source-2.6.37-rc7/drivers/char/hw_random/core.c:299
 380:   56                      push   %esi
 381:   53                      push   %ebx
...
/tmp/1/linux-source-2.6.37-rc7/drivers/char/hw_random/core.c:312
 3c6:   8b 76 1c                mov    0x1c(%esi),%esi
 3c9:   83 ee 1c                sub    $0x1c,%esi
prefetch():
/tmp/1/linux-source-2.6.37-rc7/arch/x86/include/asm/processor.h:837
 3cc:   8b 46 1c                mov    0x1c(%esi),%eax
 3cf:   8d 74 26 00             lea    0x0(%esi,%eiz,1),%esi
hwrng_register():
/tmp/1/linux-source-2.6.37-rc7/drivers/char/hw_random/core.c:312
 3d3:   81 fe f8 ff ff ff       cmp    $0xfffffff8,%esi
 3d9:   75 d4                   jne    3af <hwrng_register+0x2f>
/tmp/1/linux-source-2.6.37-rc7/drivers/char/hw_random/core.c:319

   312		list_for_each_entry(tmp, &rng_list, list) {
   313			if (strcmp(tmp->name, rng->name) == 0)
   314				goto out_unlock;
   315		}

This is btw. the same data that is accessed in the cat rng_available
crash via hwrng_attr_available_show():

[  389.303538] BUG: unable to handle kernel paging request at 288dcb5b                              
[  389.303553] IP: [<f8dda34c>] hwrng_attr_available_show+0x5c/0x90 [rng_core]                      

000002f0 <hwrng_attr_available_show>:
hwrng_attr_available_show():
/tmp/1/linux-source-2.6.37-rc7/drivers/char/hw_random/core.c:236
 2f0:   55                      push   %ebp
...
/tmp/1/linux-source-2.6.37-rc7/drivers/char/hw_random/core.c:245
 346:   8b 5b 1c                mov    0x1c(%ebx),%ebx
 349:   83 eb 1c                sub    $0x1c,%ebx
prefetch():
/tmp/1/linux-source-2.6.37-rc7/arch/x86/include/asm/processor.h:837
 34c:   8b 43 1c                mov    0x1c(%ebx),%eax
 34f:   8d 74 26 00             lea    0x0(%esi,%eiz,1),%esi
hwrng_attr_available_show():
/tmp/1/linux-source-2.6.37-rc7/drivers/char/hw_random/core.c:245

   245		list_for_each_entry(rng, &rng_list, list) {
   246			strncat(buf, rng->name, PAGE_SIZE - ret - 1);
   247			ret += strlen(rng->name);
   248			strncat(buf, " ", PAGE_SIZE - ret - 1);
   249			ret++;
   250		}


regards
   Mario
-- 
The problem in the world today is communication. Too much communication.
                                                     -- Homer J. Simpson

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