From patchwork Sun Jun 26 10:28:52 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Helge Deller X-Patchwork-Id: 585934 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 8E08BCCA481 for ; Sun, 26 Jun 2022 10:29:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229616AbiFZK3E (ORCPT ); Sun, 26 Jun 2022 06:29:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56862 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234227AbiFZK3B (ORCPT ); Sun, 26 Jun 2022 06:29:01 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.17.20]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0571C1261B for ; Sun, 26 Jun 2022 03:28:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1656239334; bh=3Sw82lkSjqZxNWiIpejvkxhMJNaG76mq4c20F06FLKg=; h=X-UI-Sender-Class:From:To:Subject:Date:In-Reply-To:References; b=DcZBE6Qsmeu2qj9Ym9F0Du83AHMv5/5hKzJu4nFeFhpK3Dx2mPljLQut6dtKOE8Ig +6iwL7S2F4iy4z/QJyngcVWsGhIEfd++gZTJwHFOy9TJrGIIAvlYXnqGSj8C5TeVUZ P6fZV/ZpJM+snBeCUyjXxoKwnjRFbtBCGF1gUMKI= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from p100.fritz.box ([92.116.135.166]) by mail.gmx.net (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1McH5Q-1nVFoQ2Ws8-00cjxr; Sun, 26 Jun 2022 12:28:54 +0200 From: Helge Deller To: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, daniel.vetter@ffwll.ch Subject: [PATCH v6 3/4] fbcon: Prevent that screen size is smaller than font size Date: Sun, 26 Jun 2022 12:28:52 +0200 Message-Id: <20220626102853.124108-4-deller@gmx.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220626102853.124108-1-deller@gmx.de> References: <20220626102853.124108-1-deller@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:R0ceq7+ogNGriXAIO0YtnBZPcu3UIWlsE4GLFTzJx2CtDdNn2DV CyuXHD3UAZUULPpTVO4DNYrBx/iobK8uLl+GHcagOvx/mMzfy0Z+6zJr/2+EBSKuHu9tuXz ZhpYhDXWNMJ9sPTH2UxHMfuKFm6XpqjINT8BKEIX8ZahGxH8tJfJMC0R8j4IcxWzha97Xeo ZtK5QU7Fs9cGMH1ThNsaw== X-UI-Out-Filterresults: notjunk:1;V03:K0:EyQ8h8phWkM=:ciNnxDzP8Po0Mfh3RR2C4N mP7Y/bST5N4D4f3QN7XXgWYnhfLeQq/fWtyQfzHwXKUi49mivy1kPCFyu3jNNqxt2XQRQZdDP 9nMQMe69JTM5D92TAJsjMcsOnbaUb0xqyUK56PR88RK4nqn1jzbVeNs+6GWAD/2db9HZfH3X5 ufUYq7GhzphbRi9Qy0vOXt+K38J8iqcNkYHkbI2S6kZeTKf8x9pAnSASEcP/hFHtJ42tDzuvi lVPBwxmE0xrZScFeeeJp0lODDZ1ua8706PRE4YWkELKHs4tckUfbN6Ac5Ky64zNHRPBQyGyum AlQR7bHRQfFKVIo9qqNeM6WA4S2XV/X6XGtGTYrIZHuoD0YOe7Co5VwcIiqX6Sh94XqV3GATQ UPUNvnWL6n3ycj7veSuvoZQx3v4N76GY3KPspb68Oh40d/vA9453Ib1VGTuBykR5pQ5iaMJ3E em4tCHpk/pEcQ1JmLLl00ofIS2kcNpdq12V1myC599cU2dzC5o2OIeoQHMsm0wzlBifcqIY0E +WtzUo82X4ZjvVLYXP/nZ9PirQE6i3aOozfUZEu7Jrr5E+haXibP1K5l4IcPPb0nwTVvEL+03 QiiKeXXvu2mepUfCBz7hKZrbIJseMd+tW5pqybI7l68gmM5sH8oY06/eeffY61ajmJMaQptX2 FUZ/cWAd6X/CAGXQpMyrBBI5rCYmkVrKCORILyXmPmsO04wuH9gG90HFy6Mru8vIJMBd/GKJa CqFEUhZdrbTlHbX39N7hPtTGkXmxOqyIs91aT/Q3+eRawZLwFQDMyNMAkWG7SVkg39TWLlFvA 828coDs36dnlk5DIeOeJIAnHRJXVFJLRmtPOwFVYyw001pjyZxSmyzwPa1Bk5onu3vnODDeer h/OCUkd4mThK1+rOYq/YbvYjjhA6SdrUK39z1QXmjN/23Uqo1eCQq5SWGmj4I696QKYZPyEb0 xqD6aio+jU224gWkou1auBIJizuPUZxJVb3lhJT5eYq+a9SiSq/9ml9R5kMAPodsMTbZPWenW uuJn75Il4zhcXEvWWgpFdUG3kVnvlAP02RUsIFXjQgaRVJhH93hYgZnGf8OA0aURTTKa/VT6t D2/NtPZHsDcgnG2PlZFoDpMDn5tYlmeDNtcZs0VC4NMo0pcIGsrrAv79w== 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 Reviewed-by: Daniel Vetter Cc: stable@vger.kernel.org # v5.4+ --- drivers/video/fbdev/core/fbcon.c | 27 +++++++++++++++++++++++++++ drivers/video/fbdev/core/fbmem.c | 4 +++- include/linux/fbcon.h | 4 ++++ 3 files changed, 34 insertions(+), 1 deletion(-) -- 2.35.3 diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c index e162d5e753e5..69c7261ac334 100644 --- a/drivers/video/fbdev/core/fbcon.c +++ b/drivers/video/fbdev/core/fbcon.c @@ -2736,6 +2736,33 @@ 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 || ops->currcon < 0) + 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 || 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 5dfa4bbee642..b6e1d0f2b974 100644 --- a/drivers/video/fbdev/core/fbmem.c +++ b/drivers/video/fbdev/core/fbmem.c @@ -1112,7 +1112,9 @@ 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; }