From mboxrd@z Thu Jan 1 00:00:00 1970 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=-11.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,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 B8C31C43381 for ; Fri, 22 Mar 2019 12:40:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 86F66218E2 for ; Fri, 22 Mar 2019 12:40:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553258419; bh=KFAqTpcknOIisZYWNJVXFD74VGXUmxezrUDFr32ASZg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=iilfQs3SpUjCe5Q9jmPlHT4Aig275yoUCAHdoW9gD+QaKyJPSTMwf2QeybryspPcj hQDRSq/I+S4UL7Ja9XDgvUf0MkFaUKcWfAjTdaAJE29u8sKd+tMwyHuZ1BZrxiNK66 FQhQwCcazJpCdeHj+iA0kInIn554iCbP8sbIBqlw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388069AbfCVMGu (ORCPT ); Fri, 22 Mar 2019 08:06:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:45270 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730757AbfCVMGt (ORCPT ); Fri, 22 Mar 2019 08:06:49 -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 769912082C; Fri, 22 Mar 2019 12:06:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553256409; bh=KFAqTpcknOIisZYWNJVXFD74VGXUmxezrUDFr32ASZg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gLwXvHG5UHFmTdWbjyKN+j5V3kothUsO8nfxVTE3ufQHJ3gyy9EhsAa09caoDDDah 4Vg83NopIZvOR6Bf+FB2UYWYCuNtnXNyG02oUgRB3F+X4pr9itAMP62hbeIgXjjlZv 7jLp3VMx93eV90jCIxBiIQ9C3apQPZWoEbJskHgo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jan Stancek , Andrea Arcangeli , Matthew Wilcox , Rafael Aquini , Minchan Kim , "Kirill A. Shutemov" , Rik van Riel , Michal Hocko , Huang Ying , Souptick Joarder , Jerome Glisse , "Aneesh Kumar K.V" , David Hildenbrand , David Rientjes , Mel Gorman , Andrew Morton , Linus Torvalds Subject: [PATCH 4.19 202/280] mm/memory.c: do_fault: avoid usage of stale vm_area_struct Date: Fri, 22 Mar 2019 12:15:55 +0100 Message-Id: <20190322111330.947117233@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190322111306.356185024@linuxfoundation.org> References: <20190322111306.356185024@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jan Stancek commit fc8efd2ddfed3f343c11b693e87140ff358d7ff5 upstream. LTP testcase mtest06 [1] can trigger a crash on s390x running 5.0.0-rc8. This is a stress test, where one thread mmaps/writes/munmaps memory area and other thread is trying to read from it: CPU: 0 PID: 2611 Comm: mmap1 Not tainted 5.0.0-rc8+ #51 Hardware name: IBM 2964 N63 400 (z/VM 6.4.0) Krnl PSW : 0404e00180000000 00000000001ac8d8 (__lock_acquire+0x7/0x7a8) Call Trace: ([<0000000000000000>] (null)) [<00000000001adae4>] lock_acquire+0xec/0x258 [<000000000080d1ac>] _raw_spin_lock_bh+0x5c/0x98 [<000000000012a780>] page_table_free+0x48/0x1a8 [<00000000002f6e54>] do_fault+0xdc/0x670 [<00000000002fadae>] __handle_mm_fault+0x416/0x5f0 [<00000000002fb138>] handle_mm_fault+0x1b0/0x320 [<00000000001248cc>] do_dat_exception+0x19c/0x2c8 [<000000000080e5ee>] pgm_check_handler+0x19e/0x200 page_table_free() is called with NULL mm parameter, but because "0" is a valid address on s390 (see S390_lowcore), it keeps going until it eventually crashes in lockdep's lock_acquire. This crash is reproducible at least since 4.14. Problem is that "vmf->vma" used in do_fault() can become stale. Because mmap_sem may be released, other threads can come in, call munmap() and cause "vma" be returned to kmem cache, and get zeroed/re-initialized and re-used: handle_mm_fault | __handle_mm_fault | do_fault | vma = vmf->vma | do_read_fault | __do_fault | vma->vm_ops->fault(vmf); | mmap_sem is released | | | do_munmap() | remove_vma_list() | remove_vma() | vm_area_free() | # vma is released | ... | # same vma is allocated | # from kmem cache | do_mmap() | vm_area_alloc() | memset(vma, 0, ...) | pte_free(vma->vm_mm, ...); | page_table_free | spin_lock_bh(&mm->context.lock);| | Cache mm_struct to avoid using potentially stale "vma". [1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/mem/mtest06/mmap1.c Link: http://lkml.kernel.org/r/5b3fdf19e2a5be460a384b936f5b56e13733f1b8.1551595137.git.jstancek@redhat.com Signed-off-by: Jan Stancek Reviewed-by: Andrea Arcangeli Reviewed-by: Matthew Wilcox Acked-by: Rafael Aquini Reviewed-by: Minchan Kim Acked-by: Kirill A. Shutemov Cc: Rik van Riel Cc: Michal Hocko Cc: Huang Ying Cc: Souptick Joarder Cc: Jerome Glisse Cc: Aneesh Kumar K.V Cc: David Hildenbrand Cc: Andrea Arcangeli Cc: David Rientjes Cc: Mel Gorman Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/memory.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/mm/memory.c +++ b/mm/memory.c @@ -3762,10 +3762,13 @@ static vm_fault_t do_shared_fault(struct * but allow concurrent faults). * The mmap_sem may have been released depending on flags and our * return value. See filemap_fault() and __lock_page_or_retry(). + * If mmap_sem is released, vma may become invalid (for example + * by other thread calling munmap()). */ static vm_fault_t do_fault(struct vm_fault *vmf) { struct vm_area_struct *vma = vmf->vma; + struct mm_struct *vm_mm = vma->vm_mm; vm_fault_t ret; /* @@ -3806,7 +3809,7 @@ static vm_fault_t do_fault(struct vm_fau /* preallocated pagetable is unused: free it */ if (vmf->prealloc_pte) { - pte_free(vma->vm_mm, vmf->prealloc_pte); + pte_free(vm_mm, vmf->prealloc_pte); vmf->prealloc_pte = NULL; } return ret;