From patchwork Wed Jul 21 18:41:31 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 12391939 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=-16.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 7AE40C636C9 for ; Wed, 21 Jul 2021 18:42:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 265AA6128A for ; Wed, 21 Jul 2021 18:42:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 265AA6128A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A75B96B005D; Wed, 21 Jul 2021 14:42:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A270F6B006C; Wed, 21 Jul 2021 14:42:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 914626B0070; Wed, 21 Jul 2021 14:42:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0077.hostedemail.com [216.40.44.77]) by kanga.kvack.org (Postfix) with ESMTP id 728106B005D for ; Wed, 21 Jul 2021 14:42:16 -0400 (EDT) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 25C2618582126 for ; Wed, 21 Jul 2021 18:42:16 +0000 (UTC) X-FDA: 78387465072.23.7080C33 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf06.hostedemail.com (Postfix) with ESMTP id 6957F802AB66 for ; Wed, 21 Jul 2021 18:42:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To:Content-Type:Content-ID: Content-Description:In-Reply-To:References; bh=QAFE3m3sGfm0XHof4+1aoQntJ/lWm+TZn6x1+h/OpC0=; b=Ph89ZAA4aD3d30oY3o18nv8iGb /7JEcnDFcyBJhO9jTARxkPybXEPs2dWWC5OAr4/6chaGfOkkSuaRxlyq/TEf4RemeTrrx4lRL9kpT KbJLI8mUEVSkmB8c2zR5FjkP1/fVj5xHjbcuByyI9ZSCyiPEBsoBS5t0N6EzTNFMmBPR+w1stoFX3 EIUAc16GkvjBNREPmf8f7LyjYxyA2+FsJKYCW9Rou6Re74Cvw2atNTPqTizJhwnqB61uGV1k/tjVr 3EclEYaqmlZhdhZkaCIVN8QWbeqS8BcjIhmZ3nIa9+iDwq5OajjWiiC/feamQb5Wxukiy7x2DPUwg sMtWidJA==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1m6H9z-009V5o-23; Wed, 21 Jul 2021 18:41:42 +0000 From: "Matthew Wilcox (Oracle)" To: Al Viro , Qualys Security Advisory , Eric Sandeen , Linus Torvalds , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: "Matthew Wilcox (Oracle)" Subject: [PATCH] mm: Make kvmalloc refuse to allocate more than 2GB Date: Wed, 21 Jul 2021 19:41:31 +0100 Message-Id: <20210721184131.2264356-1-willy@infradead.org> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=Ph89ZAA4; spf=none (imf06.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 6957F802AB66 X-Stat-Signature: 7zekkge5pujhdrnx3twbp331a59xi9yj X-HE-Tag: 1626892935-443427 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: It's generally dangerous to allocate such large quantities of memory within the kernel owing to our propensity to use 'int' to represent a length. If somebody really needs it, we can add a kvmalloc_large() later, but let's default to "You can't allocate that much memory". Signed-off-by: Matthew Wilcox (Oracle) --- fs/seq_file.c | 3 --- mm/util.c | 7 +++++++ 2 files changed, 7 insertions(+), 3 deletions(-) diff --git a/fs/seq_file.c b/fs/seq_file.c index 4a2cda04d3e2..b117b212ef28 100644 --- a/fs/seq_file.c +++ b/fs/seq_file.c @@ -32,9 +32,6 @@ static void seq_set_overflow(struct seq_file *m) static void *seq_buf_alloc(unsigned long size) { - if (unlikely(size > MAX_RW_COUNT)) - return NULL; - return kvmalloc(size, GFP_KERNEL_ACCOUNT); } diff --git a/mm/util.c b/mm/util.c index 9043d03750a7..8ff2a8924d5f 100644 --- a/mm/util.c +++ b/mm/util.c @@ -593,6 +593,13 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node) if (ret || size <= PAGE_SIZE) return ret; + /* + * Succeeding for sizes above 2GiB can lead to truncation if + * someone casts the size to an int. + */ + if (size > INT_MAX) + return NULL; + return __vmalloc_node(size, 1, flags, node, __builtin_return_address(0)); }