From patchwork Wed Jul 6 15:02:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Helge Deller X-Patchwork-Id: 12908207 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 0E799C433EF for ; Wed, 6 Jul 2022 15:03:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232052AbiGFPDF (ORCPT ); Wed, 6 Jul 2022 11:03:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49012 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232031AbiGFPDD (ORCPT ); Wed, 6 Jul 2022 11:03:03 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.17.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1626626105 for ; Wed, 6 Jul 2022 08:03:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1657119775; bh=aAI6MGei57ToZnfqLXmEk6O8X9Iu9nKAw4TPGrJ+zZw=; h=X-UI-Sender-Class:From:To:Subject:Date:In-Reply-To:References; b=UQXCk9VOh8MC38U13YmRH+oDLIyYbYMoekcu6/SxDmxCsto16359rHFgfHUYYGTv3 AdHyP55AmuY1Iq+YJz5odwDHBy4reKbKzcpUMNfmer9cGd6pItwHE+QM1WMTxqjV82 awr8vZNX5y2suon5GUj6b9t5uH9AI6X/mso40CfQ= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from p100.fritz.box ([92.116.134.81]) by mail.gmx.net (mrgmx105 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MUosT-1o04A33uEr-00QngL; Wed, 06 Jul 2022 17:02:55 +0200 From: Helge Deller To: linux-fbdev@vger.kernel.org, daniel.vetter@ffwll.ch, dri-devel@lists.freedesktop.org, geert@linux-m68k.org Subject: [PATCH v3 2/4] fbcon: Prevent that screen size is smaller than font size Date: Wed, 6 Jul 2022 17:02:51 +0200 Message-Id: <20220706150253.2186-3-deller@gmx.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220706150253.2186-1-deller@gmx.de> References: <20220706150253.2186-1-deller@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:l9wU75eBVCDkKqJs43pST5O/nc3vpHLDYyS4OlJ07y+DJXOGTUL mpIrzg2dP4h6jSvvWS3Ne/TMB0tGRZ4ljuHN9zVQULfvEGhiVHlvG+6GFtDynQN5Cb8DIKx 3ytIk0BCdhCRO0Z3xrbPEDaVPvbiC9qjTvXGzFhTVAFINLlSEjrIv5YcbvACVtbD7O9F6JN RgQEg6eyqAUapMdt3wubQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:totCYmyAkIs=:vWWIR74FuHGdFURhBJcwPf gu/sd0u5bz7wTzfK9r0GS87wvaU+CQ/ueO6ru9yDZ5gS5rDg3gOE6Q/sfN7yNXqc/4sajL4Vd SwxGTr6kAzajx4aPxssuqL4YY7neV8S5MhI+VHxnzB8/CFKoHoAw4JFMwCgO4IkwblBAM6260 dbxBnCPw5sP/Ay98SXSrjyjg6ToUPPLXGY9wziKIeEVBOfLOPIN3MpjKo0n75hhNJe8pV1fx5 cfTS0vR9sLcvrXiuEUViqkCduEAGYHkwOJmQyUZLKOPFKJze2ZjByHc641N+rpLC6H3dC6nfs DbDlwP59aeJENf8XbZTk1XdwOnLMzYcVQN/4OAdpwd9Tu/6ysVhvS0YzaF1HZG38KsEWv6sci j967a9HdQLKKdOxt4rXmAXGE6IrmrbBIBoRXJLnDBO69WSCjoIlWpU1MmUMqE5NQT/UA7S8q7 oCjnFPBz5ZkFDQR5p5ucVh2136EUK0M9vXPEJnKMY+cZyrZ28WbQ78Og6EeMSndpyjTrJfzTn hVPKOD0N+0xMTL/tKm40Hf7QKPzZT0fsIk2/Y/tJgfqbGR83LfJ8jkvQ2MQUt7aoPOoTYSzwz NKDD6C78o/lcEKgSVFJv/xLdNObqkxOf4fuY1Kf5R6F0yFG60L1J/8WJ+c4t46gZOXan4oeGH SKrVct0nvpap/hwGPlmJpXXkepAXk/wArpvX7sjlsTLtES2VVSoxb3e/hlKBYqHMqnYD5pSWY DPpc2waJeHVCVthrdYODy8UaMlVbPWbFWUhsafavTgEGDbnwAbV/vV4oK2pCIYvL53ufFsWgk VBhTb7O9JuWnDazDSe7WxIs47kxhaZe9sbk0/SBvhNuIGTUm/EfM417jBfqR3CBJvBDC1tzFa 2xH9al8OVXvmZqCRqJK2+v1p5yxX/WV97QHO0Fq8UJpVCzpkXg3UqKNH/BZ/VTjlCbp0hBZWX ePX4X7qaWNZd/bl2/MeH4nuijqlK//jzVV8YKxw6KyzaRaBBXxOud7OfuZ99f++6bkryBHqaE m1Vy+bRrSpm2DHAeCYtcl9zAoicQOqG2Y0TcdYgpE/agUi+Rkmw0/IHbAIKV3wBx3MNT8oNL6 2SqN39t6iIm1VtIG3yXbRxEz4GyxrwyHDA00wl3tlbMG8I90hSBBwrpaw== 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+ Reviewed-by: Geert Uytterhoeven --- 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..5632870a9aeb 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; + unsigned int i; + + WARN_CONSOLE_UNLOCKED(); + + if (!ops) + return 0; + + /* 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_GPL(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; }