From patchwork Tue Apr 5 07:17:44 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 557596 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 4FEFFC433EF for ; Tue, 5 Apr 2022 09:27:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347532AbiDEJ1U (ORCPT ); Tue, 5 Apr 2022 05:27:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41310 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243274AbiDEIuT (ORCPT ); Tue, 5 Apr 2022 04:50:19 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A4C212A82; Tue, 5 Apr 2022 01:38:31 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 85DE9614E5; Tue, 5 Apr 2022 08:37:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 91DB0C385A0; Tue, 5 Apr 2022 08:37:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649147874; bh=Cw2NlYAm/sub3uTEA3b2qIyrR3JDeMkKrC26amsoKtQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=giPofauEkR82o5KTt4SaFEzge6imnZO4bbsJRwgNuNnOfsuPAoPigN23SwVcwxJcJ Ujr857Hjh8ZE1fwiczus0IfLVq5IHLhKv3yq6cLMoSGEcV2cMejhFV6tK4AymRxugC NWlinx1jQerjsqpYWcwCWlQzUkxyJF2Z0aTnvMJc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zheyu Ma , Helge Deller Subject: [PATCH 5.16 0151/1017] video: fbdev: sm712fb: Fix crash in smtcfb_read() Date: Tue, 5 Apr 2022 09:17:44 +0200 Message-Id: <20220405070358.691303918@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070354.155796697@linuxfoundation.org> References: <20220405070354.155796697@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Helge Deller commit bd771cf5c4254511cc4abb88f3dab3bd58bdf8e8 upstream. Zheyu Ma reported this crash in the sm712fb driver when reading three bytes from the framebuffer: BUG: unable to handle page fault for address: ffffc90001ffffff RIP: 0010:smtcfb_read+0x230/0x3e0 Call Trace: vfs_read+0x198/0xa00 ? do_sys_openat2+0x27d/0x350 ? __fget_light+0x54/0x340 ksys_read+0xce/0x190 do_syscall_64+0x43/0x90 Fix it by removing the open-coded endianess fixup-code and by moving the pointer post decrement out the fb_readl() function. Reported-by: Zheyu Ma Signed-off-by: Helge Deller Tested-by: Zheyu Ma Cc: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/video/fbdev/sm712fb.c | 25 +++++++------------------ 1 file changed, 7 insertions(+), 18 deletions(-) --- a/drivers/video/fbdev/sm712fb.c +++ b/drivers/video/fbdev/sm712fb.c @@ -1047,7 +1047,7 @@ static ssize_t smtcfb_read(struct fb_inf if (count + p > total_size) count = total_size - p; - buffer = kmalloc((count > PAGE_SIZE) ? PAGE_SIZE : count, GFP_KERNEL); + buffer = kmalloc(PAGE_SIZE, GFP_KERNEL); if (!buffer) return -ENOMEM; @@ -1059,25 +1059,14 @@ static ssize_t smtcfb_read(struct fb_inf while (count) { c = (count > PAGE_SIZE) ? PAGE_SIZE : count; dst = buffer; - for (i = c >> 2; i--;) { - *dst = fb_readl(src++); - *dst = big_swap(*dst); + for (i = (c + 3) >> 2; i--;) { + u32 val; + + val = fb_readl(src); + *dst = big_swap(val); + src++; dst++; } - if (c & 3) { - u8 *dst8 = (u8 *)dst; - u8 __iomem *src8 = (u8 __iomem *)src; - - for (i = c & 3; i--;) { - if (i & 1) { - *dst8++ = fb_readb(++src8); - } else { - *dst8++ = fb_readb(--src8); - src8 += 2; - } - } - src = (u32 __iomem *)src8; - } if (copy_to_user(buf, buffer, c)) { err = -EFAULT;