linux-kernel - Re: [PATCH] fs:Fix kmemleak leak warning in getname_flags about working on unitialized memory

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Message-ID: <4856a8c0-890d-da93-510d-d177b9133eb5@sandeen.net>
Date:   Thu, 1 Sep 2016 12:32:51 -0500
From:   Eric Sandeen <sandeen@...deen.net>
To:     Al Viro <viro@...IV.linux.org.uk>
Cc:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        akpm@...ux-foundation.org, msalter@...hat.com,
        kuleshovmail@...il.com, david.vrabel@...rix.com, vbabka@...e.cz,
        ard.biesheuvel@...aro.org, jgross@...e.com,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [PATCH] fs:Fix kmemleak leak warning in getname_flags about
 working on unitialized memory

On 9/1/16 12:16 PM, Al Viro wrote:
> On Thu, Sep 01, 2016 at 08:10:44AM -0500, Eric Sandeen wrote:
>> On 8/4/16 8:57 AM, Al Viro wrote:
>>
>>> Don't feed the troll.  On all paths leading to that place we have
>>>         result->name = kname;
>>>         len = strncpy_from_user(kname, filename, EMBEDDED_NAME_MAX);
>>> or
>>>                 result->name = kname;
>>>                 len = strncpy_from_user(kname, filename, PATH_MAX);
>>> with failure exits taken if strncpy_from_user() returns an error, which means
>>> that the damn thing has already been copied into.
>>>
>>> FWIW, it looks a lot like buggered kmemcheck; as usual, he can't be bothered
>>> to mention which kernel version would it be (let alone how to reproduce it
>>> on the kernel in question), but IIRC davej had run into some instrumentation
>>> breakage lately.
>>
>> The original report is in https://bugzilla.kernel.org/show_bug.cgi?id=120651
>> if anyone is interested in it.
> 
> 	What the hell does that one have to getname_flags(), other than having
> attracted the same... something on the edge of failing the Turing Test?

Sigh, pasted the wrong one, thus making things worse.

I suppose reverse-engineering Nick is a fool's errand, only adding to the
noise, sorry.  I'll stop.  ;)

-Eric