From patchwork Fri Jul 1 20:22:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Helge Deller X-Patchwork-Id: 12903745 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 6EB2BC433EF for ; Fri, 1 Jul 2022 20:22:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230072AbiGAUWQ (ORCPT ); Fri, 1 Jul 2022 16:22:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55664 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229864AbiGAUWQ (ORCPT ); Fri, 1 Jul 2022 16:22:16 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.17.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3165F4F676 for ; Fri, 1 Jul 2022 13:22:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1656706928; bh=rxU496Ea/xTjK7QokoK/CvWIPeV4p8ucxlEYuQxng1c=; h=X-UI-Sender-Class:From:To:Subject:Date:In-Reply-To:References; b=Z59iAmdikPjyNlt3M36ojluNiGW75rOe2JPBiqqZ9S80nOUjatNojljF1wNNtl998 MzZG2ZlRiVLUBZWwSImL2Lk583wi3cCnQQyyqkcQSEyWCcK3l7L5y70X8YlYe7E1g2 rJclFSiN998+M1okbjsNPxSgbhzMVRHJVmoj/wgk= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from p100.fritz.box ([92.116.182.192]) by mail.gmx.net (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1M8hZJ-1o2gBy3gMj-004mLg; Fri, 01 Jul 2022 22:22:07 +0200 From: Helge Deller To: daniel.vetter@ffwll.ch, linux-fbdev@vger.kernel.org, geert@linux-m68k.org, dri-devel@lists.freedesktop.org Subject: [PATCH v2 2/4] fbcon: Prevent that screen size is smaller than font size Date: Fri, 1 Jul 2022 22:22:04 +0200 Message-Id: <20220701202206.559518-3-deller@gmx.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220701202206.559518-1-deller@gmx.de> References: <20220701202206.559518-1-deller@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:m51ZFjziku3+nLdNnQ3v0ZjANLYrgX+zAVI4+wqnuo3LHXTKQ3e CRtJBTMO9m6eiMHvEKP/jdB5AyhFb+icj6DHkaDzu6u9JLDFBzo9Q+9SHmRG1HAO6iKGQiG zt4O39ER4vg/tA9qGwOltKoG83b7MjDAV5R1WCaQhBROb/AMdYTt13f/S4fszb+hCyUe6VB fTcmaiupoDbLumxpmVAfg== X-UI-Out-Filterresults: notjunk:1;V03:K0:UWS9HLNkmOw=:rsZSHlF7Hce145g3Rp33wk IlYjaURMO0XegJLAFpgyfTi4Kpl1jG/e29w4llEIoR3uiHW0BpJJ1/SIzFsy29sELiE/2qMPM t1MwubufOIXoLL5HsfCFNtseJrpYCy3ijeyitIAwbxjknt/Q0zJU5WcjU/saPi3c5s0+wFBV8 ebLdTv9RKR5hjjdEDkUljL3J+ttwgvu1gg6i3u1En7vDwZNlQgzXzzNNtHm7yAACnWAUz57Rv BDtoRHBb5lInv219ojTmFI1pkBj3wf75GRs1g4J30unltt8SCThu11Sp0ai2BUVvpDYNcZx3F 9wsQW8Upj7FSzYlUIwDGc7tBDY4n3dSHpBY0Mk9HBdJOFePf+eK6S9fe8MyP3v89bW8j3qNWW cAuNahtBdNQJd+c+DOXzyD0esHFYGClVEd7y0LbLxGCVrUlN4pEG3k6iGdK6RpCDgoAcwCwue 1m50RqjnmcL4mbW9tIn+pIjsSGR/Mqpx9/IQ2ldfGhXx1Dcdj5UT2q7y42nfNgAFYY7B98Lzv Tc978WOl/3O+HycKd0Xkm+Hd5YTYL1DXpXrtYRjCR+kINpxWR9ax04tYRxxC0cvcGJEyQGBQ0 Dq7vc5xCKnXeEnBQYZgdzCAjn5WrYg/S866Mujk7HH9Ov9PMXKJoaDp7wNXOQuN9A4M1K+Muw YOiSmiJkDG1aG69g/mV8SQO1qyibee2n/VotOqrwyalHiDROWSlS2NiUQ9OGJ0jkb0d7uoC+C NXfwlhLlde5AO4Tq4VW3VKz3lOLEd4r7N94W0JAbBayIBcKKCfw4HfJ9Ai3Cu3qTbQjuXj3zD JgWw0Xb5FedKSXAEuN8+AjRr/TyKh6yy4NAUQa8U4WTlA37E0DoXKxagw0lsIVHY9wwP384W+ ElirBRACW/2rckdZveTXbg4maVBYbYaQYXSPuaSdFiedb5ASyyP2ADqcjkUTjsHJKnl63iqGA zMfkNNCh1qlTfI8BfmV8sS9icKn3F08LZ6gC9jbDLIoFBuQ597a1q7JmdTL/kCWoTrVGMna5a qkPOCfBHSxYtKROUyJVsCq7+/1byshkyIeSJDIphn6qTrCOvBrrt4nXYrIUptnFR1S/YC2hTe 8ILLZR9v7BfcoNZyzLN87J80pXxt7Sw5kGTwen2ZCHeJqgIoO0JgqKquA== Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org We need to prevent that users configure a screen size which is smaller than the currently selected font size. Otherwise rendering chars on the screen will access memory outside the graphics memory region. This patch adds a new function fbcon_modechange_possible() which implements this check and which later may be extended with other checks if necessary. The new function is called from the FBIOPUT_VSCREENINFO ioctl handler in fbmem.c, which will return -EINVAL if userspace asked for a too small screen size. Signed-off-by: Helge Deller Cc: stable@vger.kernel.org # v5.4+ --- drivers/video/fbdev/core/fbcon.c | 28 ++++++++++++++++++++++++++++ drivers/video/fbdev/core/fbmem.c | 4 +++- include/linux/fbcon.h | 4 ++++ 3 files changed, 35 insertions(+), 1 deletion(-) -- 2.35.3 diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index a33532564393..14b0ab51744f 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -2736,6 +2736,34 @@ void fbcon_update_vcs(struct fb_info *info, bool all) } EXPORT_SYMBOL(fbcon_update_vcs); +/* let fbcon check if it supports a new screen resolution */ +int fbcon_modechange_possible(struct fb_info *info, struct fb_var_screeninfo *var) +{ + struct fbcon_ops *ops = info->fbcon_par; + struct vc_data *vc; + int i; + + WARN_CONSOLE_UNLOCKED(); + + if (!ops) + return -EINVAL; + + /* prevent setting a screen size which is smaller than font size */ + for (i = first_fb_vc; i <= last_fb_vc; i++) { + vc = vc_cons[i].d; + if (!vc || vc->vc_mode != KD_TEXT || + registered_fb[con2fb_map[i]] != info) + continue; + + if (vc->vc_font.width > FBCON_SWAP(var->rotate, var->xres, var->yres) || + vc->vc_font.height > FBCON_SWAP(var->rotate, var->yres, var->xres)) + return -EINVAL; + } + + return 0; +} +EXPORT_SYMBOL(fbcon_modechange_possible); + int fbcon_mode_deleted(struct fb_info *info, struct fb_videomode *mode) { diff --git a/drivers/video/fbdev/core/fbmem.c b/drivers/video/fbdev/core/fbmem.c index afa2863670f3..160389365a36 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1106,7 +1106,9 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, return -EFAULT; console_lock(); lock_fb_info(info); - ret = fb_set_var(info, &var); + ret = fbcon_modechange_possible(info, &var); + if (!ret) + ret = fb_set_var(info, &var); if (!ret) fbcon_update_vcs(info, var.activate & FB_ACTIVATE_ALL); unlock_fb_info(info); diff --git a/include/linux/fbcon.h b/include/linux/fbcon.h index ff5596dd30f8..2382dec6d6ab 100644 --- a/include/linux/fbcon.h +++ b/include/linux/fbcon.h @@ -15,6 +15,8 @@ void fbcon_new_modelist(struct fb_info *info); void fbcon_get_requirement(struct fb_info *info, struct fb_blit_caps *caps); void fbcon_fb_blanked(struct fb_info *info, int blank); +int fbcon_modechange_possible(struct fb_info *info, + struct fb_var_screeninfo *var); void fbcon_update_vcs(struct fb_info *info, bool all); void fbcon_remap_all(struct fb_info *info); int fbcon_set_con2fb_map_ioctl(void __user *argp); @@ -33,6 +35,8 @@ static inline void fbcon_new_modelist(struct fb_info *info) {} static inline void fbcon_get_requirement(struct fb_info *info, struct fb_blit_caps *caps) {} static inline void fbcon_fb_blanked(struct fb_info *info, int blank) {} +static inline int fbcon_modechange_possible(struct fb_info *info, + struct fb_var_screeninfo *var) { return 0; } static inline void fbcon_update_vcs(struct fb_info *info, bool all) {} static inline void fbcon_remap_all(struct fb_info *info) {} static inline int fbcon_set_con2fb_map_ioctl(void __user *argp) { return 0; }