From patchwork Wed Dec 13 16:42:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lee Jones X-Patchwork-Id: 754308 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3B38F2FC42 for ; Wed, 13 Dec 2023 16:43:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bTqHvry3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54559C433C8; Wed, 13 Dec 2023 16:43:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702485783; bh=O6zPhvOuiRaMjZO2N7+0OTpsYUd4lm9ZY2n6Y+b+qeE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bTqHvry36GwQ2JC5GUEHK2OZj84VP8H5phOup1YRj0QFGrDNCoBXjQXSWGFMqTY0B SQymbQsSGp50F/KU/lWWhLi0U2e0DNozV3AWJ+9d3fuAF91aquJHahP80iqWziuFju hkjOv4iVYP70IxzU9YbZcmwbm8mTOTwYXC4MgQvLeq157b9PoYT2CGZyhNfAZnNZTO V+RrnfSIDC2f9xXxwuE/mK1YOLsVPywIRokO1ioLrD+PmjQIsj8BJ+Dba2RrxVcJlG CuGYuXQ832/9hEQcuiLgu/CmE8Wg9MoBvTeSZeBBADWWXAq10oQlK8ljIoBN9O7oC2 Q/UDcpIbS5EvQ== From: Lee Jones To: lee@kernel.org, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, James Gruber , Yadwinder Singh , Jaswinder Singh , Ruslan Bilovol Subject: [PATCH 03/12] usb: gadget: f_uac2: Replace snprintf() with the safer scnprintf() variant Date: Wed, 13 Dec 2023 16:42:32 +0000 Message-ID: <20231213164246.1021885-4-lee@kernel.org> X-Mailer: git-send-email 2.43.0.472.g3155946c3a-goog In-Reply-To: <20231213164246.1021885-1-lee@kernel.org> References: <20231213164246.1021885-1-lee@kernel.org> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 There is a general misunderstanding amongst engineers that {v}snprintf() returns the length of the data *actually* encoded into the destination array. However, as per the C99 standard {v}snprintf() really returns the length of the data that *would have been* written if there were enough space for it. This misunderstanding has led to buffer-overruns in the past. It's generally considered safer to use the {v}scnprintf() variants in their place (or even sprintf() in simple cases). So let's do that. Link: https://lwn.net/Articles/69419/ Link: https://github.com/KSPP/linux/issues/105 Cc: James Gruber Cc: Yadwinder Singh Cc: Jaswinder Singh Cc: Ruslan Bilovol Signed-off-by: Lee Jones --- drivers/usb/gadget/function/f_uac2.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/usb/gadget/function/f_uac2.c b/drivers/usb/gadget/function/f_uac2.c index f9a0f07a7476b..383f6854cfec5 100644 --- a/drivers/usb/gadget/function/f_uac2.c +++ b/drivers/usb/gadget/function/f_uac2.c @@ -2045,7 +2045,7 @@ static ssize_t f_uac2_opts_##name##_show(struct config_item *item, \ int result; \ \ mutex_lock(&opts->lock); \ - result = snprintf(page, sizeof(opts->name), "%s", opts->name); \ + result = scnprintf(page, sizeof(opts->name), "%s", opts->name); \ mutex_unlock(&opts->lock); \ \ return result; \ @@ -2063,7 +2063,7 @@ static ssize_t f_uac2_opts_##name##_store(struct config_item *item, \ goto end; \ } \ \ - ret = snprintf(opts->name, min(sizeof(opts->name), len), \ + ret = scnprintf(opts->name, min(sizeof(opts->name), len), \ "%s", page); \ \ end: \ @@ -2187,7 +2187,7 @@ static struct usb_function_instance *afunc_alloc_inst(void) opts->req_number = UAC2_DEF_REQ_NUM; opts->fb_max = FBACK_FAST_MAX; - snprintf(opts->function_name, sizeof(opts->function_name), "Source/Sink"); + scnprintf(opts->function_name, sizeof(opts->function_name), "Source/Sink"); opts->p_terminal_type = UAC2_DEF_P_TERM_TYPE; opts->c_terminal_type = UAC2_DEF_C_TERM_TYPE;