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[142.68.57.212]) by smtp.gmail.com with ESMTPSA id h3sm1005577qkf.15.2020.04.16.11.47.54 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Thu, 16 Apr 2020 11:47:54 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1jP9YI-0006rv-2e; Thu, 16 Apr 2020 15:47:54 -0300 Date: Thu, 16 Apr 2020 15:47:54 -0300 From: Jason Gunthorpe To: Dan Carpenter Cc: Christophe JAILLET , 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-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org 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