linux-kernel - Re: [Cluster-devel] [PATCH] gfs2: move from strlcpy with unused retval to strscpy

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Message-ID: <d53a4672-d068-c394-6ab1-058b2d72701f@redhat.com>
Date:   Thu, 25 Aug 2022 10:32:58 +0100
From:   Andrew Price <anprice@...hat.com>
To:     Wolfram Sang <wsa+renesas@...g-engineering.com>
Cc:     cluster-devel@...hat.com, linux-kernel@...r.kernel.org,
        Andreas Gruenbacher <agruenba@...hat.com>,
        Bob Peterson <rpeterso@...hat.com>
Subject: Re: [Cluster-devel] [PATCH] gfs2: move from strlcpy with unused
 retval to strscpy

On 24/08/2022 21:08, Wolfram Sang wrote:
> Hi Andy.
> 
>>> -	strlcpy(sdp->sd_proto_name, proto, GFS2_FSNAME_LEN);
>>> -	strlcpy(sdp->sd_table_name, table, GFS2_FSNAME_LEN);
>>> +	strscpy(sdp->sd_proto_name, proto, GFS2_FSNAME_LEN);
>>> +	strscpy(sdp->sd_table_name, table, GFS2_FSNAME_LEN);
>>
>> Perhaps the size should be changed to GFS2_LOCKNAME_LEN to match the size of
>> the destination, too.
>>
>> With that addition, this patch fixes this syzkaller report:
>>
>> https://listman.redhat.com/archives/cluster-devel/2022-August/022755.html
> 
> Linus wrote another summary about strlcpy vs. strscpy use[1]. So, the
> size argument should be the size of the smaller buffer if the buffers
> are of different size. GFS2_LOCKNAME_LEN is smaller, so that looks
> suitable. Shall I resend the patch with the suggested change?

Yes, please. I can't speak for the gfs2 maintainers but I think it would 
be a good plan, as the combination of strscpy and the size change fixes 
a bug.

Andy

> 
> All the best,
> 
>     Wolfram
> 
> [1] https://lore.kernel.org/lkml/CAHk-=wi+xbVq++uqW9YgWpHjyBHNB8a-xad+Xp23-B+eodLCEA@mail.gmail.com/
>