From patchwork Wed Dec 13 16:42:36 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lee Jones X-Patchwork-Id: 754306 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 92A6A2FC42 for ; Wed, 13 Dec 2023 16:43:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="OikvGNj6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83C16C433C9; Wed, 13 Dec 2023 16:43:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1702485791; bh=wYZoxRzv7f2lUWGVcUrdQYjqojzH2JSBWrtkL9KlpB4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OikvGNj6sd0jUETMSWlDSLI5ZF/U+uXbQ8cVDaFNlkARUf5qtCOPFz/y3XWqThSt8 cEuyEzZacvtERUMB5wriCrNSxDOFQtiDQjRRTxmdNqT4jo0SCEsVbcIY82OKRdZhoH HM3VYJzdSXnumn5UpTJomk69ro5yyp6jl7AOUaWDuuP+JqilQ2Ux4CVJ6q9s2iGbFC Mztob5uy85eoJrWtcOrBgI8hOAMk+iahwGDNv38hzfGSXFeILsO2PIfr1PGFEoWQ6o 8k9KL+WzlfxAxmaxUjYswgOY4eP+iOTNwsQj6Sn+XvHB0Id3BUw94U00TfCDWIDGN6 DcKnJuEBEW5tQ== From: Lee Jones To: lee@kernel.org, gregkh@linuxfoundation.org Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org, Cristian Birsan , Nicolas Ferre , Alexandre Belloni , Claudiu Beznea , linux-arm-kernel@lists.infradead.org Subject: [PATCH 07/12] usb: host: max3421-hcd: Replace snprintf() with the safer scnprintf() variant Date: Wed, 13 Dec 2023 16:42:36 +0000 Message-ID: <20231213164246.1021885-8-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: Cristian Birsan Cc: Nicolas Ferre Cc: Alexandre Belloni Cc: Claudiu Beznea Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: Lee Jones --- drivers/usb/host/max3421-hcd.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/drivers/usb/host/max3421-hcd.c b/drivers/usb/host/max3421-hcd.c index d152d72de1269..9fe4f48b18980 100644 --- a/drivers/usb/host/max3421-hcd.c +++ b/drivers/usb/host/max3421-hcd.c @@ -1158,12 +1158,12 @@ dump_eps(struct usb_hcd *hcd) end = dp + sizeof(ubuf); *dp = '\0'; list_for_each_entry(urb, &ep->urb_list, urb_list) { - ret = snprintf(dp, end - dp, " %p(%d.%s %d/%d)", urb, - usb_pipetype(urb->pipe), - usb_urb_dir_in(urb) ? "IN" : "OUT", - urb->actual_length, - urb->transfer_buffer_length); - if (ret < 0 || ret >= end - dp) + ret = scnprintf(dp, end - dp, " %p(%d.%s %d/%d)", urb, + usb_pipetype(urb->pipe), + usb_urb_dir_in(urb) ? "IN" : "OUT", + urb->actual_length, + urb->transfer_buffer_length); + if (ret == end - dp - 1) break; /* error or buffer full */ dp += ret; } @@ -1255,9 +1255,9 @@ max3421_handle_irqs(struct usb_hcd *hcd) end = sbuf + sizeof(sbuf); *dp = '\0'; for (i = 0; i < 16; ++i) { - int ret = snprintf(dp, end - dp, " %lu", - max3421_hcd->err_stat[i]); - if (ret < 0 || ret >= end - dp) + int ret = scnprintf(dp, end - dp, " %lu", + max3421_hcd->err_stat[i]); + if (ret == end - dp - 1) break; /* error or buffer full */ dp += ret; }