From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752003AbcCHUm0 (ORCPT ); Tue, 8 Mar 2016 15:42:26 -0500 Received: from mail-wm0-f48.google.com ([74.125.82.48]:36174 "EHLO mail-wm0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751702AbcCHUlI (ORCPT ); Tue, 8 Mar 2016 15:41:08 -0500 From: Rasmus Villemoes To: Kees Cook , Andrew Morton , Kalle Valo Cc: Rasmus Villemoes , linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [RFC 5/7] wlcore: avoid fragile snprintf use Date: Tue, 8 Mar 2016 21:40:52 +0100 Message-Id: <1457469654-17059-6-git-send-email-linux@rasmusvillemoes.dk> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1457469654-17059-1-git-send-email-linux@rasmusvillemoes.dk> References: <1457469654-17059-1-git-send-email-linux@rasmusvillemoes.dk> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Appending to a buffer like this is not guaranteed to work (passing overlapping src and dst buffers to snprintf is undefined behaviour). The standard and safe idiom is to keep track of the current string length. Signed-off-by: Rasmus Villemoes --- drivers/net/wireless/ti/wlcore/boot.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/drivers/net/wireless/ti/wlcore/boot.c b/drivers/net/wireless/ti/wlcore/boot.c index 19b7ec7b69c2..401d75c02bf4 100644 --- a/drivers/net/wireless/ti/wlcore/boot.c +++ b/drivers/net/wireless/ti/wlcore/boot.c @@ -86,7 +86,7 @@ static int wlcore_validate_fw_ver(struct wl1271 *wl) unsigned int *min_ver = (wl->fw_type == WL12XX_FW_TYPE_MULTI) ? wl->min_mr_fw_ver : wl->min_sr_fw_ver; char min_fw_str[32] = ""; - int i; + int i, len; /* the chip must be exactly equal */ if ((min_ver[FW_VER_CHIP] != WLCORE_FW_VER_IGNORE) && @@ -119,13 +119,15 @@ static int wlcore_validate_fw_ver(struct wl1271 *wl) return 0; fail: + len = 0; for (i = 0; i < NUM_FW_VER; i++) if (min_ver[i] == WLCORE_FW_VER_IGNORE) - snprintf(min_fw_str, sizeof(min_fw_str), - "%s*.", min_fw_str); + len += scnprintf(min_fw_str + len, + sizeof(min_fw_str) - len, "*."); else - snprintf(min_fw_str, sizeof(min_fw_str), - "%s%u.", min_fw_str, min_ver[i]); + len += scnprintf(min_fw_str + len, + sizeof(min_fw_str) - len, + "%u.", min_ver[i]); wl1271_error("Your WiFi FW version (%u.%u.%u.%u.%u) is invalid.\n" "Please use at least FW %s\n" -- 2.1.4