Re: [PATCH 05/11] xfsprogs: xfs_mdrestore: check bad read count in perform_restore

[Eric Sandeen <sandeen@sandeen.net>]

On 12/2/15 11:59 PM, Dave Chinner wrote:
> On Wed, Dec 02, 2015 at 10:54:19PM -0600, Eric Sandeen wrote:
>> On 12/2/15 5:19 AM, Vivek Trivedi wrote:
>>> fix error reported by coverity - Integer overflowed argument
>>>
>>> also, add print incase of invalid read count to get more debug
>>> information.
>>>
>>> Signed-off-by: Vivek Trivedi <t.vivek@samsung.com>
>>> ---
>>>  mdrestore/xfs_mdrestore.c |    4 ++++
>>>  1 file changed, 4 insertions(+)
>>>
>>> diff --git a/mdrestore/xfs_mdrestore.c b/mdrestore/xfs_mdrestore.c
>>> index 5764616..a87a091 100644
>>> --- a/mdrestore/xfs_mdrestore.c
>>> +++ b/mdrestore/xfs_mdrestore.c
>>> @@ -93,6 +93,10 @@ perform_restore(
>>>  	block_index = (__be64 *)((char *)metablock + sizeof(xfs_metablock_t));
>>>  	block_buffer = (char *)metablock + block_size;
>>>  
>>> +	if (block_size < sizeof(tmb))
>>> +		fatal("bad read count, block_size: %d, tmb size %d\n",
>>> +				block_size, sizeof(tmb));
>>> +
>>
>> block_size is block_size = 1 << tmb.mb_blocklog; where mb_blocklog is
>> always metablock->mb_blocklog = BBSHIFT;, so block_size is always 512.
>>
>> On the other hand, sizeof(tmb) is simply 8.
>>
>> There seems to be no possible path for this to be a problem, so it hardly
>> seems worth the printf.
>>
>> Would an ASSERT(block_size >= sizeof(tmb)) make coverity happy?
> 
> Just ignoring this coverity warning would be more appropriate, i
> think.

Or that ... FWIW this one does not even show up in the coverity scan project
as an issue.

-Eric

> Cheers,
> 
> Dave.
> 

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