linux-kernel - Re: [PATCH]Fix potential Divide by Zero error in ext2_get

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Message-ID: <4A0C027F.8070806@in.ibm.com>
Date:	Thu, 14 May 2009 17:07:35 +0530
From:	"B. N. Poornima" <poornima@...ibm.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH]Fix potential Divide by Zero error in ext2_get_inode()

Andrew Morton wrote:
> On Wed, 13 May 2009 13:51:01 +0530
> "B. N. Poornima" <poornima@...ibm.com> wrote:
>
>   
>> Found a line of code in ext2_get_inode function of inode.c in the ext2 
>> filesystem that has the potential of hitting the divide by 0 error.
>> *************************************************
>>  block_group = (ino - 1) / EXT2_INODES_PER_GROUP(sb);
>> *************************************************
>> There is no checking done here to verify if EXT2_INODES_PER_GROUP() 
>> returns 0. This could result in divide by zero error and panic the system.
>> Below is the patch, built against 2.6.30-rc5,  to correct the same:
>>     
>
> EXT2_INODES_PER_GROUP() cannot return zero.  See ext2_fill_super():
>
> 	if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
> 		goto cantfind_ext2;
>
>   
Andrew,
Thanks for pointing that out!

Regards,
Poornima.
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