linux-kernel - Re: [PATCH] ext4: prefer strlcpy to strncpy

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Message-ID: <20180530051458.GB27959@thunk.org>
Date:   Wed, 30 May 2018 01:14:58 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Nick Desaulniers <nick.desaulniers@...il.com>
Cc:     adilger.kernel@...ger.ca, linux-ext4@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ext4: prefer strlcpy to strncpy

On Mon, May 28, 2018 at 11:21:53PM -0700, Nick Desaulniers wrote:
> Fixes a stringop-truncation warning from gcc-8.
> 
> Signed-off-by: Nick Desaulniers <nick.desaulniers@...il.com>

I'll note that the ext4 superblock fields are *not* guaranteed to be
NULL terminated.  Code that references them must, and do, deal with
this appropriately.  See for example:

https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/tree/lib/e2p/ls.c#n436

GCC-8 may whine about it, but the whine is, in fact, not correct.
It's making assumptions about all strings being null terminated, which
is often, but not always, the case.

Cheers,

						- Ted