From patchwork Wed Dec 13 16:42:30 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lee Jones X-Patchwork-Id: 754309 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 133F1364CB for ; Wed, 13 Dec 2023 16:42:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="D6sduuO3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5C8AC433C9; Wed, 13 Dec 2023 16:42:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702485778; bh=9hIznFcw8DaH/AT2cUPzctof/XKOI1gZcHfpU8gxwaE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D6sduuO3AhilOynckvUN791n2U8Y+YaO3mW522cT/m1JUmQEpDCLOCrW5Cbge2pzE wCeH4/KlBpDTS75d7/yK4zhfzS3jtlWJ/4nv2aRg+1voRfHkDtx9HoV55S1iI8CAn6 FYj0fOh+aYgp3wSNEDlKQ8IEkwLy1m5upNThpQqwLWHrORUGTzDLdQpG7pbcUvSl/X H3u8eXWfQSTY2LWM6oGkjZjJOnlF/R4zBoI4IO1k5aLy7RaKi8lGt5fPAl9yZMZpAB Ig+ngBEtwwDSiUsmbroyS6nTForV/Biy0aj/61+WxgtHuNBQqRQ/YtU4Cbgi9UIu47 cm2orOSHOmxcQ== From: Lee Jones To: lee@kernel.org, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Subject: [PATCH 01/12] usb: gadget: configfs: Replace snprintf() with the safer scnprintf() variant Date: Wed, 13 Dec 2023 16:42:30 +0000 Message-ID: <20231213164246.1021885-2-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 Signed-off-by: Lee Jones --- drivers/usb/gadget/configfs.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c index b7d2a1313a684..ce3cfa1f36f51 100644 --- a/drivers/usb/gadget/configfs.c +++ b/drivers/usb/gadget/configfs.c @@ -606,10 +606,11 @@ static struct config_group *function_make( char *instance_name; int ret; - ret = snprintf(buf, MAX_NAME_LEN, "%s", name); - if (ret >= MAX_NAME_LEN) + if (strlen(name) >= MAX_NAME_LEN) return ERR_PTR(-ENAMETOOLONG); + scnprintf(buf, MAX_NAME_LEN, "%s", name); + func_name = buf; instance_name = strchr(func_name, '.'); if (!instance_name) { @@ -701,10 +702,12 @@ static struct config_group *config_desc_make( int ret; gi = container_of(group, struct gadget_info, configs_group); - ret = snprintf(buf, MAX_NAME_LEN, "%s", name); - if (ret >= MAX_NAME_LEN) + + if (strlen(name) >= MAX_NAME_LEN) return ERR_PTR(-ENAMETOOLONG); + scnprintf(buf, MAX_NAME_LEN, "%s", name); + num_str = strchr(buf, '.'); if (!num_str) { pr_err("Unable to locate . in name.bConfigurationValue\n");