From patchwork Sat Jun 25 23:27:02 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Helge Deller X-Patchwork-Id: 585193 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 594CBC433EF for ; Sat, 25 Jun 2022 23:27:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233693AbiFYX1L (ORCPT ); Sat, 25 Jun 2022 19:27:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51710 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233550AbiFYX1K (ORCPT ); Sat, 25 Jun 2022 19:27:10 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.15.18]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 226B212629 for ; Sat, 25 Jun 2022 16:27:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1656199624; bh=nfABXp4+4Nirl11sxz+LuJ8G0460lBsNCoiDTu/FQT8=; h=X-UI-Sender-Class:From:To:Subject:Date:In-Reply-To:References; b=RNxzvEfkKBXioLdUqcCbzQXsHLs+ViVgfhiDCTbVbca6S1Q/EidBqj6hpo7OPcuPB bX2kAyVyG/soQtIvcog9QzcsfIQvB05ePZufsk3UhGfU+2/4JaFy1mYiGT2s13b2j9 dTXjW+gocryUUJGYhJFauuF+U2oEGTGCCrhd9lGI= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from p100.fritz.box ([92.116.162.44]) by mail.gmx.net (mrgmx004 [212.227.17.190]) with ESMTPSA (Nemesis) id 1MeU0k-1nUoQu2QoG-00aSns; Sun, 26 Jun 2022 01:27:04 +0200 From: Helge Deller To: dri-devel@lists.freedesktop.org, daniel.vetter@ffwll.ch, linux-fbdev@vger.kernel.org Subject: [PATCH v4 2/3] fbcon: Prevent that screen size is smaller than font size Date: Sun, 26 Jun 2022 01:27:02 +0200 Message-Id: <20220625232703.401821-3-deller@gmx.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220625232703.401821-1-deller@gmx.de> References: <20220625232703.401821-1-deller@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:wkuZk46WpVrZtroQJngQJ56MT8kBhZUkpKEwH0MihMZLa3la8eY c88p54UrCwJZ2vo6KLnTBzkuU02KKxr1xvlF8EtvpGHEaP7kk1+7+r7tCAq+zOX1LQjZyhx HxcHT3zyAp34+aZNb6Z11TC3I6bZewvBg6e8SM9g2TJOvrY9YbTCPM/5kcK4Svm0IZETsol J6tmz/hx9l5JNPrMw2txQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:Tt+6iidaFxo=:Uf8yC0Lrwlb/Uym78a7o+H xi30oinsHXhpB8Lqx8xjWUSXouEoTLrMgGKJQyFPxQkr2QTo4YFatb5JRaNzBB8XC9+bCFVB1 SPtz63DkwsRQF1Bb9UJWmelzHq5LKewzB9uo7yPLCyyUS2i7REicn6aB5PGYDLSfnhjlPcLzv NwUj4KWnHbcUmG/YqDAgwJrcekHzrCLL5fdmI5zlUMP5byuDoKhsB7zJddf+cc5xWfTnH/NbA N+tvW8yJKyC7z7xNN201n0KHC4nDRx1HYt/MWDv801rYOntMBU437nh5f+ss+/zldqlF2jqOX 7ER5o6jhk6LVPEq/fKcdFaHj3I0d6Jq5pUfYINkOXa1H8Lr/gJp6eP6LjqZI52x/C6OfCfZ+p YaDx+uqzmKCvDHopatfKaEtO79Xzz3W61UhtZyUXIoNiB5Ms+KyVMxtWvrU7/jKOSz1mMxSON 0+S9BnNR9qVqZUmvZmS/mCeb2e+Kl96Z6DqxhTkydAdobmp8FpYFe9vqT1XryLhzCE/1SzU3+ 6u6xnHUxG2BzUEnoZGQEj08WmeVuiC3rOOU+qbDIVVvb1xmoyk5ennRd3R5LPM+aOujXgw+je g3qFbQurRLoozwKnZEzxnHTUXhelzRFPp4ciMaLcSJU4xSLSWPpkiDNggLZo5AzRy5dqTqLXn Q7JGIlyF4zlTaflf4La7HO2MUCjFoEByqVNM2Ov+NY7VHPON2rkqEcadOflUax/4jNQfnX12f 2HyWDXzKJAXlDlWM6VS/q78a51t5ixSuszMyn2VS/D2edFLpEdsb5s/3SFkuhYRk1hknIBbbJ 2Ur9kojDD1VwEFl0F4eesr90aau5K8q/LUbPDFNO+9CSvAJuv7nKn8XzaTSeQbmej6EROMaNL wN2YnukILbaEld/sgTvWiO9s4SKWsE7em35RqqyP7tt1pWCiWdsnsInvFJ8RSHZIgVRKe0kbF QQMS/VOJUGEKmLP102yw9qJf9dhcEZrrY+d1e8OuYHTvKwrM19PuAeLPXKdICjTSY/QvTNWsZ KHEnXuN3PzZGpYEV9VG28RgVoimWHA8b5CBq6qiv4ff/EIaQuLMHour8TeSpysTQvXEsBJlxu c3/dLL5M6Dd8Ci839pY8/GHa7bcX+SCFBg4XKQ9WTmqZoZuftRFm2elUw== 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. This patch depends on commit 409d6c95f9c6 ("fbcon: Introduce wrapper for console->fb_info lookup"), so it needs to be backported as well. Signed-off-by: Helge Deller 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..2ab7515ac842 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 || fbcon_info_from_console(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; }