linux-kernel - Re: [PATCH] bfs: prevent underflow in bfs_find

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Message-ID: <CAK+_RLk3D1VA6Rms1TGEFuEeO8JGxUaXfmWxznn+cHCG96TOTQ@mail.gmail.com>
Date:   Tue, 10 Mar 2020 18:22:42 +0000
From:   Tigran Aivazian <aivazian.tigran@...il.com>
To:     Walter Harms <wharms@....de>
Cc:     Dan Carpenter <dan.carpenter@...cle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH] bfs: prevent underflow in bfs_find_entry()

Hello,

On Tue, 10 Mar 2020 at 17:57, Walter Harms <wharms@....de> wrote:
> that raises the question why is there a len paramter in the first place.
> Surely the writer can make sure that there is always a NUL terminated
> string, then it would be possible the use a simple strcmp() and the
> range check is useless and can be removed.
>
> seems a question for the maintainer.

Please have a look at, for example,
fs/ufs/dir.c:ufs_find_entry()/ufs_match() functions --- they do almost
the same thing as the ones in bfs. And, presumably, the line "int
namelen = qstr->len;" in ufs_find_entry() is causing the static
checker warning too, just like the one in bfs which Dan mentioned and
fixed. So, let's not over-complicate things (or make a mountain out of
a molehill) and accept Dan's patch as is.

Kind regards,
Tigran