Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Thu, 16 Apr 2020 15:47:54 -0300
From:   Jason Gunthorpe <jgg@ziepe.ca>
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     Christophe JAILLET <christophe.jaillet@wanadoo.fr>,
        selvin.xavier@broadcom.com, devesh.sharma@broadcom.com,
        dledford@redhat.com, leon@kernel.org, colin.king@canonical.com,
        roland@purestorage.com, linux-rdma@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: Re: [PATCH] RDMA/ocrdma: Fix an off-by-one issue in 'ocrdma_add_stat'
Message-ID: <20200416184754.GZ5100@ziepe.ca>
References: <20200328073040.24429-1-christophe.jaillet@wanadoo.fr>
 <20200414183441.GA28870@ziepe.ca>
 <20200416130847.GP1163@kadam>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20200416130847.GP1163@kadam>
User-Agent: Mutt/1.9.4 (2018-02-28)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, Apr 16, 2020 at 04:08:47PM +0300, Dan Carpenter wrote:
> On Tue, Apr 14, 2020 at 03:34:41PM -0300, Jason Gunthorpe wrote:
> > The memcpy is still kind of silly right? What about this:
> > 
> > static int ocrdma_add_stat(char *start, char *pcur, char *name, u64 count)
> > {
> > 	size_t len = (start + OCRDMA_MAX_DBGFS_MEM) - pcur;
> > 	int cpy_len;
> > 
> > 	cpy_len = snprintf(pcur, len, "%s: %llu\n", name, count);
> > 	if (cpy_len >= len || cpy_len < 0) {
> 
> The kernel version of snprintf() doesn't and will never return
> negatives.  It would cause a huge security headache if it started
> returning negatives.

Begs the question why it returns an int then :)

Thanks,
Jason