linux-kernel - Re: CIFS kernel module bug

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Date:	Fri, 30 Sep 2011 13:30:10 -0500
From:	Steve French <smfrench@...il.com>
To:	Jeff Layton <jlayton@...ba.org>
Cc:	Anton Altaparmakov <aia21@....ac.uk>,
	Steve French <sfrench@...ba.org>, linux-cifs@...r.kernel.org,
	samba-technical@...ts.samba.org,
	LKML <linux-kernel@...r.kernel.org>,
	PWF Linux <pwf-linux@....cam.ac.uk>
Subject: Re: CIFS kernel module bug

On Fri, Sep 30, 2011 at 1:04 PM, Jeff Layton <jlayton@...ba.org> wrote:
> On Fri, 30 Sep 2011 14:58:58 +0100
> Anton Altaparmakov <aia21@....ac.uk> wrote:
>
>> Hi,
>>
>> Looking at the current kernel (in Linus' repository on github) there is a silly logic bug in the cifs module in fs/cifs/cifsfs.c::cifs_llseek() there is this bit of code:
>>
>>       /*
>>        * origin == SEEK_END || SEEK_DATA || SEEK_HOLE => we must revalidate
>>        * the cached file length
>>        */
>>       if (origin != SEEK_SET || origin != SEEK_CUR) {
>>
>> The logical or should be a logical and, i.e. this should be:
>>
>>       if (origin != SEEK_SET && origin != SEEK_CUR) {
>>
>> As the code is at present that line is ALWAYS true because origin is ALWAYS either != SEEK_SET or != SEEK_CUR as if it equals one it cannot equal the other and vice versa…
>>
>> So at the moment it always does the revalidation instead of only for SEEK_END, SEEK_DATA, and SEEK_HOLE.
>>
>> Best regards,
>>
>>       Anton
>
>
> Haha, good catch. Care to roll up a patch to fix that?
>
> --
> Jeff Layton <jlayton@...ba.org>
>


Yes - obviously that code was wrong, fortunately not a disaster.
Thanks for pointing this out.  If you don't want to write up
the patch let us know and we will make the trivial fix.



-- 
Thanks,

Steve
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