From patchwork Thu Dec 16 21:53:50 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Matthew Wilcox (Oracle)" X-Patchwork-Id: 12682813 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 59526C433F5 for ; Thu, 16 Dec 2021 21:54:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237091AbhLPVyF (ORCPT ); Thu, 16 Dec 2021 16:54:05 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36292 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234629AbhLPVyE (ORCPT ); Thu, 16 Dec 2021 16:54:04 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 97806C061574 for ; Thu, 16 Dec 2021 13:54:04 -0800 (PST) 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: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=jtkiEbeC8BH5Pq80FDCgjIrecOy7gCyzuNpIoqv5nX0=; b=DJwMtd4jnj3lLUZ0yZEetfivZS yHv/lAf3GgRuYuwfu+huJY7nUxInXVVeByfxdMGwS5hqgKQJ84T2U8CKSkeyGAiHgx8gkHXfZcgoG sKBEaiNe5/E1+e0r4Tpn6imTF3zEb0kR7cV63MHAw5vyfVgKmw0mWBepC4nLc8yORAoFz8+vOs0+Z ovsmwRtjUjuwwhdV0gD5gEDHCYxnafQGZNkPVAOdvCv8oprVEhVeBksy+xwLZaKni5TwIlT2AcUpF mBOd4vqvve/ATY6CGdt7feEV3gC/hWEPRGaJCNGVlfeYhingGDFntV5fwgvkM+thA2//m/JRAmgEi PDhy927A==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mxyhE-00FzYA-RJ; Thu, 16 Dec 2021 21:53:52 +0000 From: "Matthew Wilcox (Oracle)" To: Kees Cook Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, linux-hardening@vger.kernel.org, William Kucharski Subject: [PATCH v4 3/4] mm/usercopy: Detect compound page overruns Date: Thu, 16 Dec 2021 21:53:50 +0000 Message-Id: <20211216215351.3811471-4-willy@infradead.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211216215351.3811471-1-willy@infradead.org> References: <20211216215351.3811471-1-willy@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org Move the compound page overrun detection out of CONFIG_HARDENED_USERCOPY_PAGESPAN so it's enabled for more people. Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Kees Cook Reviewed-by: William Kucharski --- mm/usercopy.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/mm/usercopy.c b/mm/usercopy.c index 63476e1506e0..db2e8c4f79fd 100644 --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -163,7 +163,6 @@ static inline void check_page_span(const void *ptr, unsigned long n, { #ifdef CONFIG_HARDENED_USERCOPY_PAGESPAN const void *end = ptr + n - 1; - struct page *endpage; bool is_reserved, is_cma; /* @@ -194,11 +193,6 @@ static inline void check_page_span(const void *ptr, unsigned long n, ((unsigned long)end & (unsigned long)PAGE_MASK))) return; - /* Allow if fully inside the same compound (__GFP_COMP) page. */ - endpage = virt_to_head_page(end); - if (likely(endpage == page)) - return; - /* * Reject if range is entirely either Reserved (i.e. special or * device memory), or CMA. Otherwise, reject since the object spans @@ -258,6 +252,11 @@ static inline void check_heap_object(const void *ptr, unsigned long n, if (PageSlab(page)) { /* Check slab allocator for flags and size. */ __check_heap_object(ptr, n, page, to_user); + } else if (PageHead(page)) { + /* A compound allocation */ + unsigned long offset = ptr - page_address(page); + if (offset + n > page_size(page)) + usercopy_abort("page alloc", NULL, to_user, offset, n); } else { /* Verify object does not incorrectly span multiple pages. */ check_page_span(ptr, n, page, to_user);