From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: [PATCH 4.14 40/72] x86/earlyprintk/efi: Fix infinite loop on some screen widths Date: Thu, 20 Dec 2018 10:18:39 +0100 Message-ID: <20181220085923.925075636@linuxfoundation.org> References: <20181220085922.332225035@linuxfoundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20181220085922.332225035@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, YiFei Zhu , Ard Biesheuvel , Andy Lutomirski , Arend van Spriel , Bhupesh Sharma , Borislav Petkov , Dave Hansen , Eric Snowberg , Hans de Goede , Joe Perches , Jon Hunter , Julien Thierry , Linus Torvalds , Marc Zyngier , Matt Fleming , Nathan Chancellor , Peter Zijlstra , Sai List-Id: linux-efi@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 79c2206d369b87b19ac29cb47601059b6bf5c291 ] An affected screen resolution is 1366 x 768, which width is not divisible by 8, the default font width. On such screens, when longer lines are earlyprintk'ed, overflow-to-next-line can never trigger, due to the left-most x-coordinate of the next character always less than the screen width. Earlyprintk will infinite loop in trying to print the rest of the string but unable to, due to the line being full. This patch makes the trigger consider the right-most x-coordinate, instead of left-most, as the value to compare against the screen width threshold. Signed-off-by: YiFei Zhu Signed-off-by: Ard Biesheuvel Cc: Andy Lutomirski Cc: Arend van Spriel Cc: Bhupesh Sharma Cc: Borislav Petkov Cc: Dave Hansen Cc: Eric Snowberg Cc: Hans de Goede Cc: Joe Perches Cc: Jon Hunter Cc: Julien Thierry Cc: Linus Torvalds Cc: Marc Zyngier Cc: Matt Fleming Cc: Nathan Chancellor Cc: Peter Zijlstra Cc: Sai Praneeth Prakhya Cc: Sedat Dilek Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20181129171230.18699-12-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- arch/x86/platform/efi/early_printk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/platform/efi/early_printk.c b/arch/x86/platform/efi/early_printk.c index 5fdacb322ceb..c3e6be110b7d 100644 --- a/arch/x86/platform/efi/early_printk.c +++ b/arch/x86/platform/efi/early_printk.c @@ -179,7 +179,7 @@ early_efi_write(struct console *con, const char *str, unsigned int num) num--; } - if (efi_x >= si->lfb_width) { + if (efi_x + font->width > si->lfb_width) { efi_x = 0; efi_y += font->height; } -- 2.19.1 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6655EC43387 for ; Thu, 20 Dec 2018 09:27:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 32FBC217D7 for ; Thu, 20 Dec 2018 09:27:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545298020; bh=Ruo0XwTyg3PADOlTU1Z9wP0mQuz30Wb2HFovacYqTgU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ORLptL8Jdz3GhU4Z9yCqDDskXZHJVrFhpKtYLv0oD92DbAt7UD99uEf/g0yLaaOJN OL43jF+dca+v13+L5Z9rbM0qSoquC/chqOjBU0wERuFDWka9OG8NzAqydJ0WqBB7Vm u+QwXIS4uYChsP/gSyV7FDA+98znIzkgizfDsEX8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729710AbeLTJ07 (ORCPT ); Thu, 20 Dec 2018 04:26:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:59654 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732190AbeLTJ04 (ORCPT ); Thu, 20 Dec 2018 04:26:56 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 70549218AE; Thu, 20 Dec 2018 09:26:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1545298014; bh=Ruo0XwTyg3PADOlTU1Z9wP0mQuz30Wb2HFovacYqTgU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1J3OYy+TmYksDPUCQacwTR6SSzp51KnyC521lqQG3zUj/H8LGJvDPxh0W+K/ynbsl S7FWqR0wtw/z5b4/rda8tOECw4hpjiOuCp+3e4R3RHNOXfrgHpckz9e1m12YpTfpJO Z3PNOv/GG4KPEpbZfYig4GNeojPfnOMWiKELRaJE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, YiFei Zhu , Ard Biesheuvel , Andy Lutomirski , Arend van Spriel , Bhupesh Sharma , Borislav Petkov , Dave Hansen , Eric Snowberg , Hans de Goede , Joe Perches , Jon Hunter , Julien Thierry , Linus Torvalds , Marc Zyngier , Matt Fleming , Nathan Chancellor , Peter Zijlstra , Sai Praneeth Prakhya , Sedat Dilek , Thomas Gleixner , linux-efi@vger.kernel.org, Ingo Molnar , Sasha Levin Subject: [PATCH 4.14 40/72] x86/earlyprintk/efi: Fix infinite loop on some screen widths Date: Thu, 20 Dec 2018 10:18:39 +0100 Message-Id: <20181220085923.925075636@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20181220085922.332225035@linuxfoundation.org> References: <20181220085922.332225035@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit 79c2206d369b87b19ac29cb47601059b6bf5c291 ] An affected screen resolution is 1366 x 768, which width is not divisible by 8, the default font width. On such screens, when longer lines are earlyprintk'ed, overflow-to-next-line can never trigger, due to the left-most x-coordinate of the next character always less than the screen width. Earlyprintk will infinite loop in trying to print the rest of the string but unable to, due to the line being full. This patch makes the trigger consider the right-most x-coordinate, instead of left-most, as the value to compare against the screen width threshold. Signed-off-by: YiFei Zhu Signed-off-by: Ard Biesheuvel Cc: Andy Lutomirski Cc: Arend van Spriel Cc: Bhupesh Sharma Cc: Borislav Petkov Cc: Dave Hansen Cc: Eric Snowberg Cc: Hans de Goede Cc: Joe Perches Cc: Jon Hunter Cc: Julien Thierry Cc: Linus Torvalds Cc: Marc Zyngier Cc: Matt Fleming Cc: Nathan Chancellor Cc: Peter Zijlstra Cc: Sai Praneeth Prakhya Cc: Sedat Dilek Cc: Thomas Gleixner Cc: linux-efi@vger.kernel.org Link: http://lkml.kernel.org/r/20181129171230.18699-12-ard.biesheuvel@linaro.org Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- arch/x86/platform/efi/early_printk.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/platform/efi/early_printk.c b/arch/x86/platform/efi/early_printk.c index 5fdacb322ceb..c3e6be110b7d 100644 --- a/arch/x86/platform/efi/early_printk.c +++ b/arch/x86/platform/efi/early_printk.c @@ -179,7 +179,7 @@ early_efi_write(struct console *con, const char *str, unsigned int num) num--; } - if (efi_x >= si->lfb_width) { + if (efi_x + font->width > si->lfb_width) { efi_x = 0; efi_y += font->height; } -- 2.19.1