From patchwork Mon Dec 13 14:27:01 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 12674041 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 02D0EC433FE for ; Mon, 13 Dec 2021 14:27:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238788AbhLMO1J (ORCPT ); Mon, 13 Dec 2021 09:27:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39760 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238701AbhLMO1J (ORCPT ); Mon, 13 Dec 2021 09:27:09 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E021AC061574 for ; Mon, 13 Dec 2021 06:27:08 -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=w4DGbDmVukCMyumUVjlvoObtquEzMdIQjJeODulGmAg=; b=ZGTG9RBHJQ+3OwtP7bwSuPAYs7 4v/rtpNhXZNZEswO89WfIWQ70Rqn6FC975hC0jOYPETLMLeKoNxr2ejcHD5TI59Gq5XDR/hSlJTrp Sndpy4vJbVYcVATgRiSZ4v8N8yhqjPvTqCYaFJ+X6R+uMGUqehb7nsjkkMcszbZ/7RAGvcWUKruZp SAcH8oICLC4WjM+sOUhYWx2sdfE/eCoiNyGwZd8/Ot3CgppP1mDOKIBJtCUH4SiEQlR+TDNeelBD5 KePtJUfVhVbzyZK0NHjU4UpteIItnd86Nf9rbuPhUaegO8gEC9OSUTlGNMd05lyT/zDoKGyqrohA6 K471n/hg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mwmID-00Crlt-6Y; Mon, 13 Dec 2021 14:27:05 +0000 From: "Matthew Wilcox (Oracle)" To: Kees Cook Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, Thomas Gleixner , linux-hardening@vger.kernel.org Subject: [PATCH v3 1/3] mm/usercopy: Check kmap addresses properly Date: Mon, 13 Dec 2021 14:27:01 +0000 Message-Id: <20211213142703.3066590-2-willy@infradead.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211213142703.3066590-1-willy@infradead.org> References: <20211213142703.3066590-1-willy@infradead.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org If you are copying to an address in the kmap region, you may not copy across a page boundary, no matter what the size of the underlying allocation. You can't kmap() a slab page because slab pages always come from low memory. Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Kees Cook --- arch/x86/include/asm/highmem.h | 1 + include/linux/highmem-internal.h | 10 ++++++++++ mm/usercopy.c | 16 ++++++++++------ 3 files changed, 21 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/highmem.h b/arch/x86/include/asm/highmem.h index 032e020853aa..731ee7cc40a5 100644 --- a/arch/x86/include/asm/highmem.h +++ b/arch/x86/include/asm/highmem.h @@ -26,6 +26,7 @@ #include #include #include +#include /* declarations for highmem.c */ extern unsigned long highstart_pfn, highend_pfn; diff --git a/include/linux/highmem-internal.h b/include/linux/highmem-internal.h index 0a0b2b09b1b8..01fb76d101b0 100644 --- a/include/linux/highmem-internal.h +++ b/include/linux/highmem-internal.h @@ -149,6 +149,11 @@ static inline void totalhigh_pages_add(long count) atomic_long_add(count, &_totalhigh_pages); } +static inline bool is_kmap_addr(const void *x) +{ + unsigned long addr = (unsigned long)x; + return addr >= PKMAP_ADDR(0) && addr < PKMAP_ADDR(LAST_PKMAP); +} #else /* CONFIG_HIGHMEM */ static inline struct page *kmap_to_page(void *addr) @@ -234,6 +239,11 @@ static inline void __kunmap_atomic(void *addr) static inline unsigned int nr_free_highpages(void) { return 0; } static inline unsigned long totalhigh_pages(void) { return 0UL; } +static inline bool is_kmap_addr(const void *x) +{ + return false; +} + #endif /* CONFIG_HIGHMEM */ /* diff --git a/mm/usercopy.c b/mm/usercopy.c index b3de3c4eefba..8c039302465f 100644 --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -228,12 +228,16 @@ static inline void check_heap_object(const void *ptr, unsigned long n, if (!virt_addr_valid(ptr)) return; - /* - * When CONFIG_HIGHMEM=y, kmap_to_page() will give either the - * highmem page or fallback to virt_to_page(). The following - * is effectively a highmem-aware virt_to_head_page(). - */ - page = compound_head(kmap_to_page((void *)ptr)); + if (is_kmap_addr(ptr)) { + unsigned long page_end = (unsigned long)ptr | (PAGE_SIZE - 1); + + if ((unsigned long)ptr + n - 1 > page_end) + usercopy_abort("kmap", NULL, to_user, + offset_in_page(ptr), n); + return; + } + + page = virt_to_head_page(ptr); if (PageSlab(page)) { /* Check slab allocator for flags and size. */