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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 2EA67C4361B for ; Sun, 6 Dec 2020 06:15:19 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CB7C82312D for ; Sun, 6 Dec 2020 06:15:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CB7C82312D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 668AD6B007D; Sun, 6 Dec 2020 01:15:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 5F24F6B007E; Sun, 6 Dec 2020 01:15:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4B9DF6B0080; Sun, 6 Dec 2020 01:15:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0057.hostedemail.com [216.40.44.57]) by kanga.kvack.org (Postfix) with ESMTP id 348AF6B007D for ; Sun, 6 Dec 2020 01:15:18 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id ECB788249980 for ; Sun, 6 Dec 2020 06:15:17 +0000 (UTC) X-FDA: 77561845074.04.boats80_510e3f0273d3 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin04.hostedemail.com (Postfix) with ESMTP id D2C1580019BD for ; Sun, 6 Dec 2020 06:15:17 +0000 (UTC) X-HE-Tag: boats80_510e3f0273d3 X-Filterd-Recvd-Size: 3881 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf01.hostedemail.com (Postfix) with ESMTP for ; Sun, 6 Dec 2020 06:15:17 +0000 (UTC) Date: Sat, 05 Dec 2020 22:15:15 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1607235316; bh=S5T9snE/qxxRE5C1ixuUvr1S8OmU5pS8Mg83NSxZzqc=; h=From:To:Subject:In-Reply-To:From; b=Lf+c5c0GmFMmyKo2VB4QmT0Kr1mRczVdgisFsG01yR7xYei+d42HyiURngj4CJGQp w5RnEiJRf7HnAzOcN9DZEmMwf0jkYT5rN+H9kNVusYDHTLe5iPKsuHBk8qjmfDop2y DXCKXbIvGOH10Sk63spwKwwcOV34ZEFAv7wGTuQ8= From: Andrew Morton To: akpm@linux-foundation.org, david@redhat.com, hushiyuan@huawei.com, jgg@nvidia.com, linmiaohe@huawei.com, linux-mm@kvack.org, liuzixian4@huawei.com, louhongxiang@huawei.com, mm-commits@vger.kernel.org, torvalds@linux-foundation.org, willy@infradead.org Subject: [patch 12/12] mm/mmap.c: fix mmap return value when vma is merged after call_mmap() Message-ID: <20201206061515.sa2v5S_CL%akpm@linux-foundation.org> In-Reply-To: <20201205221412.67f14b9b3a5ef531c76dd452@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Liu Zixian Subject: mm/mmap.c: fix mmap return value when vma is merged after call_mmap() On success, mmap should return the begin address of newly mapped area, but patch "mm: mmap: merge vma after call_mmap() if possible" set vm_start of newly merged vma to return value addr. Users of mmap will get wrong address if vma is merged after call_mmap(). We fix this by moving the assignment to addr before merging vma. We have a driver which changes vm_flags, and this bug is found by our testcases. Link: https://lkml.kernel.org/r/20201203085350.22624-1-liuzixian4@huawei.com Fixes: d70cec898324 ("mm: mmap: merge vma after call_mmap() if possible") Signed-off-by: Liu Zixian Reviewed-by: Jason Gunthorpe Reviewed-by: David Hildenbrand Cc: Miaohe Lin Cc: Hongxiang Lou Cc: Hu Shiyuan Cc: Matthew Wilcox Signed-off-by: Andrew Morton --- mm/mmap.c | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-) --- a/mm/mmap.c~fix-mmap-return-value-when-vma-is-merged-after-call_mmap +++ a/mm/mmap.c @@ -1808,6 +1808,17 @@ unsigned long mmap_region(struct file *f if (error) goto unmap_and_free_vma; + /* Can addr have changed?? + * + * Answer: Yes, several device drivers can do it in their + * f_op->mmap method. -DaveM + * Bug: If addr is changed, prev, rb_link, rb_parent should + * be updated for vma_link() + */ + WARN_ON_ONCE(addr != vma->vm_start); + + addr = vma->vm_start; + /* If vm_flags changed after call_mmap(), we should try merge vma again * as we may succeed this time. */ @@ -1822,25 +1833,12 @@ unsigned long mmap_region(struct file *f fput(vma->vm_file); vm_area_free(vma); vma = merge; - /* Update vm_flags and possible addr to pick up the change. We don't - * warn here if addr changed as the vma is not linked by vma_link(). - */ - addr = vma->vm_start; + /* Update vm_flags to pick up the change. */ vm_flags = vma->vm_flags; goto unmap_writable; } } - /* Can addr have changed?? - * - * Answer: Yes, several device drivers can do it in their - * f_op->mmap method. -DaveM - * Bug: If addr is changed, prev, rb_link, rb_parent should - * be updated for vma_link() - */ - WARN_ON_ONCE(addr != vma->vm_start); - - addr = vma->vm_start; vm_flags = vma->vm_flags; } else if (vm_flags & VM_SHARED) { error = shmem_zero_setup(vma); _