linux-kernel - Re: Possible coding issue in udf??

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Message-Id: <AA3F896F-8054-4981-8D43-A48A76C0087E@dilger.ca>
Date:	Sun, 15 May 2011 10:32:11 -0600
From:	Andreas Dilger <adilger@...ger.ca>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Alex Davis <alex14641@...oo.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>
Subject: Re: Possible coding issue in udf??

On 2011-05-15, at 9:14 AM, Andi Kleen <andi@...stfloor.org> wrote:
> Alex Davis <alex14641@...oo.com> writes:
>> In fs/udf/inode.c, line 1455, linux 2.6.35, there is the following code:
>> 
>>    udfperms = ((inode->i_mode & S_IRWXO)) |
>>           ((inode->i_mode & S_IRWXG) << 2) |
>>           ((inode->i_mode & S_IRWXU) << 4);
>> 
>> Shouldn't we be shifting by 3 bits? i.e:
>>    udfperms = ((inode->i_mode & S_IRWXO)) |
>>           ((inode->i_mode & S_IRWXG) << 3) |
>>           ((inode->i_mode & S_IRWXU) << 6);
>> 
>> The S_I.. constants are all defined in include/linux/stat.h as 3-bit values.
>> 
>> I will send a patch if needed.
> 
> I  would suggest you test it first. Put in a UDF disk that triggers
> this case (verify with a printk). Check in ls -l if the 
> permissions are correct or wrong.

Typically I would agree. In this case ir looks like the existing code doesn't make sense, because it will be overlapping the R and X bits from the adjacent U, G, and O masks. 

Cheers, Andreas--
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