From patchwork Tue Apr 28 18:25:12 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "gregkh@linuxfoundation.org" X-Patchwork-Id: 226847 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 49397C83000 for ; Tue, 28 Apr 2020 18:45:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2B4B02085B for ; Tue, 28 Apr 2020 18:45:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588099557; bh=nZOTCztkrvm3VQFpmLiXSlzVzJMlPmcb9EM8YgnLKNc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ah1drN1JXdAoBVIomAIfjkU+hEbOwQHv4+Pab7uYLTppixC3DGErf/CbtfMNADM1t t32mZacDiUtC7IS4/D/XpH75pLo6Dyr3Uf+t8g/ZpTv+YxGjW9M9dvDCCQKM6+19vS i0AugJYmhbO4LHWoAR4tl49FStMXwjUV3J9eSrUU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730117AbgD1Sp4 (ORCPT ); Tue, 28 Apr 2020 14:45:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:36400 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731286AbgD1Snp (ORCPT ); Tue, 28 Apr 2020 14:43:45 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.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 CD7A9206D6; Tue, 28 Apr 2020 18:43:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588099425; bh=nZOTCztkrvm3VQFpmLiXSlzVzJMlPmcb9EM8YgnLKNc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MlEP6qukCmabBaIpFrK51+F/SQRszHXzj1fTiGjIMXNYjMuS/XQTI69fhBquEmm1E aBWgg6coBNWvH7MCfZf9NpuISu4vdCZn3SncJD+Lw95Lj8MjhVu3Yye1m4djlTKtYP rYqWezhxACfkZnP5kkJZz9+UI8AiQFjo1AQQjYTI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicolas Pitre Subject: [PATCH 5.4 138/168] vt: dont hardcode the mem allocation upper bound Date: Tue, 28 Apr 2020 20:25:12 +0200 Message-Id: <20200428182249.274231503@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200428182231.704304409@linuxfoundation.org> References: <20200428182231.704304409@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nicolas Pitre commit 2717769e204e83e65b8819c5e2ef3e5b6639b270 upstream. The code in vc_do_resize() bounds the memory allocation size to avoid exceeding MAX_ORDER down the kzalloc() call chain and generating a runtime warning triggerable from user space. However, not only is it unwise to use a literal value here, but MAX_ORDER may also be configurable based on CONFIG_FORCE_MAX_ZONEORDER. Let's use KMALLOC_MAX_SIZE instead. Note that prior commit bb1107f7c605 ("mm, slab: make sure that KMALLOC_MAX_SIZE will fit into MAX_ORDER") the KMALLOC_MAX_SIZE value could not be relied upon. Signed-off-by: Nicolas Pitre Cc: # v4.10+ Link: https://lore.kernel.org/r/nycvar.YSQ.7.76.2003281702410.2671@knanqh.ubzr Signed-off-by: Greg Kroah-Hartman --- drivers/tty/vt/vt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -1206,7 +1206,7 @@ static int vc_do_resize(struct tty_struc if (new_cols == vc->vc_cols && new_rows == vc->vc_rows) return 0; - if (new_screen_size > (4 << 20)) + if (new_screen_size > KMALLOC_MAX_SIZE) return -EINVAL; newscreen = kzalloc(new_screen_size, GFP_USER); if (!newscreen)