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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 05B14C04AB3 for ; Mon, 27 May 2019 21:11:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DCA2120815 for ; Mon, 27 May 2019 21:11:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727327AbfE0VL0 (ORCPT ); Mon, 27 May 2019 17:11:26 -0400 Received: from mga04.intel.com ([192.55.52.120]:23653 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727148AbfE0VLZ (ORCPT ); Mon, 27 May 2019 17:11:25 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 27 May 2019 14:11:24 -0700 X-ExtLoop1: 1 Received: from rpedgeco-mobl.amr.corp.intel.com (HELO localhost.intel.com) ([10.251.0.167]) by orsmga008.jf.intel.com with ESMTP; 27 May 2019 14:11:24 -0700 From: Rick Edgecombe To: linux-kernel@vger.kernel.org, peterz@infradead.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, luto@kernel.org Cc: dave.hansen@intel.com, namit@vmware.com, Rick Edgecombe , Meelis Roos , "David S. Miller" , Borislav Petkov , Ingo Molnar Subject: [PATCH v5 2/2] vmalloc: Avoid rare case of flushing tlb with weird arguments Date: Mon, 27 May 2019 14:10:58 -0700 Message-Id: <20190527211058.2729-3-rick.p.edgecombe@intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190527211058.2729-1-rick.p.edgecombe@intel.com> References: <20190527211058.2729-1-rick.p.edgecombe@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In a rare case, flush_tlb_kernel_range() could be called with a start higher than the end. In vm_remove_mappings(), in case page_address() returns 0 for all pages (for example they were all in highmem), _vm_unmap_aliases() will be called with start = ULONG_MAX, end = 0 and flush = 1. If at the same time, the vmalloc purge operation is triggered by something else while the current operation is between remove_vm_area() and _vm_unmap_aliases(), then the vm mapping just removed will be already purged. In this case the call of vm_unmap_aliases() may not find any other mappings to flush and so end up flushing start = ULONG_MAX, end = 0. So only set flush = true if we find something in the direct mapping that we need to flush, and this way this can't happen. Fixes: 868b104d7379 ("mm/vmalloc: Add flag for freeing of special permsissions") Cc: Meelis Roos Cc: Peter Zijlstra Cc: "David S. Miller" Cc: Dave Hansen Cc: Borislav Petkov Cc: Andy Lutomirski Cc: Ingo Molnar Cc: Nadav Amit Signed-off-by: Rick Edgecombe --- mm/vmalloc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 3ede9c064477..7f15a3ebcd74 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2125,6 +2125,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) { unsigned long start = ULONG_MAX, end = 0; int flush_reset = area->flags & VM_FLUSH_RESET_PERMS; + int flush_dmap = 0; int i; /* @@ -2164,6 +2165,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) if (addr) { start = min(addr, start); end = max(addr + PAGE_SIZE, end); + flush_dmap = 1; } } @@ -2173,7 +2175,7 @@ static void vm_remove_mappings(struct vm_struct *area, int deallocate_pages) * reset the direct map permissions to the default. */ set_area_direct_map(area, set_direct_map_invalid_noflush); - _vm_unmap_aliases(start, end, 1); + _vm_unmap_aliases(start, end, flush_dmap); set_area_direct_map(area, set_direct_map_default_noflush); } -- 2.20.1