From patchwork Fri Jul 1 20:23:50 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Helge Deller X-Patchwork-Id: 12903756 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 58FC5C43334 for ; Fri, 1 Jul 2022 20:24:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231545AbiGAUYF (ORCPT ); Fri, 1 Jul 2022 16:24:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231167AbiGAUYC (ORCPT ); Fri, 1 Jul 2022 16:24:02 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.17.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC2B62ED5B for ; Fri, 1 Jul 2022 13:23:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1656707034; bh=rxU496Ea/xTjK7QokoK/CvWIPeV4p8ucxlEYuQxng1c=; h=X-UI-Sender-Class:From:To:Subject:Date:In-Reply-To:References; b=GyqwgUOV836pRDoRizlIXluIsdOvu32xv5SDibU8jYsvUhfHQYOgdaluGwsNTpX8a Qm9eg3TlKLm47nwbCMhu5LsHJEo2tlO+BS0y8/iB9iz0TWlPjiLcOg1xr2dINLAmU5 zFOmkfkR3FWJrGNs9YFerOsGY9nuxq2qMkYTgn5c= 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 1Mnpnm-1nIO2d3Nd4-00pN1a; Fri, 01 Jul 2022 22:23:53 +0200 From: Helge Deller To: geert@linux-m68k.org, dri-devel@lists.freedesktop.org, daniel.vetter@ffwll.ch, linux-fbdev@vger.kernel.org Subject: [PATCH v2 2/4] fbcon: Prevent that screen size is smaller than font size Date: Fri, 1 Jul 2022 22:23:50 +0200 Message-Id: <20220701202352.559808-3-deller@gmx.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20220701202352.559808-1-deller@gmx.de> References: <20220701202352.559808-1-deller@gmx.de> MIME-Version: 1.0 X-Provags-ID: V03:K1:ZHYTlOGKyFeiwiZa2YYz4S0Wnm6R1fmU1XmicS4cmLNG0W7rv4T G/QJb0lvetmDVHjRM1rmOMzXWnWvwdsRas3Wc/l6o7mLiyztK1U8cPeDtLZyDOJDSCGuqIf Pc0bYbHR8MfUfsSWK7V7oK6FOyapwC/HYjjgzmyHqB85DJyoEkmXkHqeynFzJ6vdqvyuu12 03zLzYgcWQhfM/QGnQr5w== X-UI-Out-Filterresults: notjunk:1;V03:K0:TQhVhJaK0ks=:ZoWst0gtGN1bRV5t8yived vle+ooyvJswph8i1Re1hTZ3fahmnvv3uL5VKPXOrAGuBaIypBUDfhzO6T85x4Po1RzVGOreFp 32jGIpEtzBoUxCimNOMs0m7mXF62gU69gxB9c11NB58pnS9Q+Ta8TznMVhOD/Gh/msFYMEPjp rB7vtAREmwmyAVbsBccd2vjIiN1Rx1cCgzpSqor6Lk/pN15ecYfmgHUAwgHqS7NM2QacBkHyj jJHqfKHi+/Sxn72QrdYNDsx5Bm1Vy6MD9MoFW5lgTRqvGWccrK7n2TeiXDX/adZmCxItdI7xB WZ7fxSifXCDBZuCYHdoWl9Zpa1LY81Ws74ZBwoeeMCvGaK8QhAhZJ+UpkIndyZ85mn8TIJJAB dnDpKPuL9OySs2UbJNtFA+4kKGPR8pyvzcZ77qzfakQgZnq3JBKZMds6khKYb1mN+BKK0vZME P1K4LzB91zo3sm0hVupLzR2onwdJv8jLFWxxoxNt1mr8NttTq39nkU9sza2kJyfCCOy6tAfSf UWrv7QyBvjJ1SgysScXTw56jJWtwu2nZsgEuQ/kQd9lhpVRJaeTZImlZjKuEzjF1PGGLKN81G 3hYqdqXp7KSAWz/sK7QCBgC6ywF/11w3S2miw0wfVht0VK5FJn+kalEzLtQGImELvrblTCiYl 1u3TA4GtmSJ1sfpE8Q8uW+tcJP1sDKrb8+xOOuenz+KrbADQKI44Vp+ae7BfE6imPLtu4BEqu JSa83FeMsSEEi9vEIPQHmPXFNk9W3PJ6EIERf4GJl/G+xCuWBnaP4ukr/ttKPIpWlrDjFBLDj qdE4Kx3HcUgDGZ/EGJaHz0qcjcQ7cYsfJ4gHIx6Dq5UeewNYbxBItPYEGDdpx8LNFpCP0B2Fm 8Zn2SYqHDgPycEpNldyR9EZCEaEOp0hWvu1ysu2r+BMEtgStiP82sKz/LACxveaYXcCxTo0il Kf7S3ZAvZOXB8/L1FDFPfQTSePSs68am8uHjCEHrNCIz84Siz1Uq2KuHU8oMjfWf/fpG2+cYb yrEuE+e6a3Kt0J8OqU3Zv8zxLpu5k5JsxNjsARbWdsYDftOHifRzbFCLPZwSJAS/CHnFlXe3k q4ZCYb0ht4xVJh2u3+NYA/6HO4bpZZ5d1fIq+QkYN1fFJ9x6JIktBgi1w== 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; }