From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 803F7EE49B2 for ; Thu, 31 Aug 2023 22:16:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345735AbjHaWQJ (ORCPT ); Thu, 31 Aug 2023 18:16:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38156 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229634AbjHaWQJ (ORCPT ); Thu, 31 Aug 2023 18:16:09 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 81ED2C0; Thu, 31 Aug 2023 15:16:02 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 1942FB82428; Thu, 31 Aug 2023 22:16:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 65A00C433C7; Thu, 31 Aug 2023 22:15:57 +0000 (UTC) Date: Fri, 1 Sep 2023 00:15:54 +0200 From: Helge Deller To: Nick Desaulniers Cc: linux-fbdev@vger.kernel.org, dri-devel , clang-built-linux , LKML , Andrew Morton , Nathan Chancellor , Kees Cook , Justin Stitt Subject: Re: truncation in drivers/video/fbdev/neofb.c Message-ID: References: <9d2bb495-0c1d-0d1b-96ea-4b1110d45b79@gmx.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org * Nick Desaulniers : > On Thu, Aug 31, 2023 at 2:23 PM Helge Deller wrote: > > > > * Helge Deller : > > > On 8/29/23 18:45, Nick Desaulniers wrote: > > > > A recent change in clang made it better about spotting snprintf that > > > > will result in truncation. Nathan reported the following instances: > > > > > > > > drivers/video/fbdev/neofb.c:1959:3: warning: 'snprintf' will always be > > > > truncated; specified size is 16, but format string expands to at least > > > > 17 [-Wfortify-source] > > > > FYI, I've added the patch below to the fbdev for-next git tree. > > [...] > > This indeed makes the warning go away, but that's more so due to the > use of strscpy now rather than snprintf. That alone is a good change > but we still have definite truncation. See below: > [...] Nick, thanks for your review and findings! Now every string should be max. 15 chars (which fits with the trailing NUL into the char[16] array). Helge Subject: [PATCH] fbdev: neofb: Shorten Neomagic product name in info struct Avoid those compiler warnings: neofb.c:1959:3: warning: 'snprintf' will always be truncated; specified size is 16, but format string expands to at least 17 [-Wfortify-source] Signed-off-by: Helge Deller Reported-by: Nathan Chancellor Reported-by: Nick Desaulniers Link: https://lore.kernel.org/all/CAKwvOdn0xoVWjQ6ufM_rojtKb0f1i1hW-J_xYGfKDNFdHwaeHQ@mail.gmail.com/ Link: https://github.com/ClangBuiltLinux/linux/issues/1923 diff --git a/drivers/video/fbdev/neofb.c b/drivers/video/fbdev/neofb.c index d2f622b4c372..b58b11015c0c 100644 --- a/drivers/video/fbdev/neofb.c +++ b/drivers/video/fbdev/neofb.c @@ -1948,49 +1948,40 @@ static struct fb_info *neo_alloc_fb_info(struct pci_dev *dev, switch (info->fix.accel) { case FB_ACCEL_NEOMAGIC_NM2070: - snprintf(info->fix.id, sizeof(info->fix.id), - "MagicGraph 128"); + strscpy(info->fix.id, "MagicGraph128", sizeof(info->fix.id)); break; case FB_ACCEL_NEOMAGIC_NM2090: - snprintf(info->fix.id, sizeof(info->fix.id), - "MagicGraph 128V"); + strscpy(info->fix.id, "MagicGraph128V", sizeof(info->fix.id)); break; case FB_ACCEL_NEOMAGIC_NM2093: - snprintf(info->fix.id, sizeof(info->fix.id), - "MagicGraph 128ZV"); + strscpy(info->fix.id, "MagicGraph128ZV", sizeof(info->fix.id)); break; case FB_ACCEL_NEOMAGIC_NM2097: - snprintf(info->fix.id, sizeof(info->fix.id), - "MagicGraph 128ZV+"); + strscpy(info->fix.id, "Mag.Graph128ZV+", sizeof(info->fix.id)); break; case FB_ACCEL_NEOMAGIC_NM2160: - snprintf(info->fix.id, sizeof(info->fix.id), - "MagicGraph 128XD"); + strscpy(info->fix.id, "MagicGraph128XD", sizeof(info->fix.id)); break; case FB_ACCEL_NEOMAGIC_NM2200: - snprintf(info->fix.id, sizeof(info->fix.id), - "MagicGraph 256AV"); + strscpy(info->fix.id, "MagicGraph256AV", sizeof(info->fix.id)); info->flags |= FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_COPYAREA | FBINFO_HWACCEL_FILLRECT; break; case FB_ACCEL_NEOMAGIC_NM2230: - snprintf(info->fix.id, sizeof(info->fix.id), - "MagicGraph 256AV+"); + strscpy(info->fix.id, "Mag.Graph256AV+", sizeof(info->fix.id)); info->flags |= FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_COPYAREA | FBINFO_HWACCEL_FILLRECT; break; case FB_ACCEL_NEOMAGIC_NM2360: - snprintf(info->fix.id, sizeof(info->fix.id), - "MagicGraph 256ZX"); + strscpy(info->fix.id, "MagicGraph256ZX", sizeof(info->fix.id)); info->flags |= FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_COPYAREA | FBINFO_HWACCEL_FILLRECT; break; case FB_ACCEL_NEOMAGIC_NM2380: - snprintf(info->fix.id, sizeof(info->fix.id), - "MagicGraph 256XL+"); + strscpy(info->fix.id, "Mag.Graph256XL+", sizeof(info->fix.id)); info->flags |= FBINFO_HWACCEL_IMAGEBLIT | FBINFO_HWACCEL_COPYAREA | FBINFO_HWACCEL_FILLRECT;