From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:34012 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753208AbdKVKTC (ORCPT ); Wed, 22 Nov 2017 05:19:02 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn , Linus Torvalds Subject: [PATCH 4.14 12/18] mm/pagewalk.c: report holes in hugetlb ranges Date: Wed, 22 Nov 2017 11:12:36 +0100 Message-Id: <20171122101149.118508156@linuxfoundation.org> In-Reply-To: <20171122101148.598610049@linuxfoundation.org> References: <20171122101148.598610049@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jann Horn commit 373c4557d2aa362702c4c2d41288fb1e54990b7c upstream. This matters at least for the mincore syscall, which will otherwise copy uninitialized memory from the page allocator to userspace. It is probably also a correctness error for /proc/$pid/pagemap, but I haven't tested that. Removing the `walk->hugetlb_entry` condition in walk_hugetlb_range() has no effect because the caller already checks for that. This only reports holes in hugetlb ranges to callers who have specified a hugetlb_entry callback. This issue was found using an AFL-based fuzzer. v2: - don't crash on ->pte_hole==NULL (Andrew Morton) - add Cc stable (Andrew Morton) Fixes: 1e25a271c8ac ("mincore: apply page table walker on do_mincore()") Signed-off-by: Jann Horn Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/pagewalk.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -188,8 +188,12 @@ static int walk_hugetlb_range(unsigned l do { next = hugetlb_entry_end(h, addr, end); pte = huge_pte_offset(walk->mm, addr & hmask, sz); - if (pte && walk->hugetlb_entry) + + if (pte) err = walk->hugetlb_entry(pte, hmask, addr, next, walk); + else if (walk->pte_hole) + err = walk->pte_hole(addr, next, walk); + if (err) break; } while (addr = next, addr != end);