linux-ext4 - Re: [PATCH] ext4: fix null pointer deref on mount

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Date:	Tue, 6 Jan 2009 08:25:09 -0500
From:	Theodore Tso <tytso@....edu>
To:	Thiemo Nagel <thiemo.nagel@...tum.de>
Cc:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Subject: Re: [PATCH] ext4: fix null pointer deref on mount

On Tue, Jan 06, 2009 at 01:46:23PM +0100, Thiemo Nagel wrote:
>>> @@ -2160,6 +2162,15 @@
>>>  			EXT4_BLOCKS_PER_GROUP(sb) - 1);
>>>  	do_div(blocks_count, EXT4_BLOCKS_PER_GROUP(sb));
>>>  	sbi->s_groups_count = blocks_count;
>>> +	if (sbi->s_groups_count > ((uint64_t)1<<32) - EXT4_DESC_PER_BLOCK(sb)) {
>>
>> This can't possibly work, given that s_groups_count is an unsigned
>> int.
>
> I'm casting to uint64_t, so in my opinion it should work on all  
> architectures.

... which doesn't help given that sbi->s_groups_count is 32 bits on
x86_32 machines if it is unsigned long, and always 32 bits once
ext4_group_t was changed to be an unsigned int.

						- Ted

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