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

[Andrew Price <anprice@redhat.com>]

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/
>