Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:6 as permitted sender) client-ip=2620:137:e000::3:6;
Date:   Tue, 10 Oct 2023 11:23:06 +0900
From:   asmadeus@codewreck.org
To:     Christian Schoenebeck <linux_oss@crudebyte.com>
Cc:     ericvh@kernel.org, lucho@ionkov.net, Su Hui <suhui@nfschina.com>,
        v9fs@lists.linux.dev, linux-kernel@vger.kernel.org,
        kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] fs/9p/xattr.c: avoid format-overflow warning
Message-ID: <ZSS1irFMxC35cg01@codewreck.org>
References: <20231008060138.517057-1-suhui@nfschina.com>
 <13910281.Zj71IQSfG8@silver>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <13910281.Zj71IQSfG8@silver>
Precedence: bulk

Christian Schoenebeck wrote on Mon, Oct 09, 2023 at 08:34:15PM +0200:
> > +++ b/fs/9p/xattr.c
> > @@ -139,7 +139,7 @@ int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
> >  
> >  ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
> >  {
> > -	return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
> > +	return v9fs_xattr_get(dentry, "", buffer, buffer_size);
> >  }
> >  
> >  static int v9fs_xattr_handler_get(const struct xattr_handler *handler,
> > 
> 
> Mmm, that's not the same is it? Have you tested this change?
> 
> Currently this function causes a 'Txattrwalk' 9p message to be sent to 9p
> server with its name[s] field being NULL, and the latter being the magical
> hint to 9p server to not send an attribute, but rather the list of attributes.
> 
> With your change I would assume that it would rather ask server for one
> attribute called "". I have not tested myself, just worrying that it might
> break behaviour.

p9pdu_vwritef should output the same (just a 0 length) for both NULL and
"" so I think it should be ok, but it definitely needs testing.

I'll try to find time to check (getfattr -d should be enough) later this
week and add it to the pile

-- 
Dominique Martinet | Asmadeus