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=-6.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 99B64C433DF for ; Fri, 21 Aug 2020 00:42:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6DAD82087D for ; Fri, 21 Aug 2020 00:42:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597970540; bh=H0TlMLU7cAofjPmQz4xfJlF0ssVRdl3/ZmHYO3yDzvk=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=Gn91rPvqbr0qxBcbGorKIW0ymFugxBsAvDxG/aleBrXa534gx8r5yA9qy3UjsWAnM bbdbPfEsZgI0ARzl6OxP6Aded6lLRoJzbV38BhLxNWSNs9qh/Y9ef8gnkt81O6k1Fn 8rRkPKfaBWGNnPgTCfvhaPaX37gqGMeR5ANojtWc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727031AbgHUAmU (ORCPT ); Thu, 20 Aug 2020 20:42:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:35674 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727012AbgHUAmT (ORCPT ); Thu, 20 Aug 2020 20:42:19 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 5DC6822B3F; Fri, 21 Aug 2020 00:42:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597970538; bh=H0TlMLU7cAofjPmQz4xfJlF0ssVRdl3/ZmHYO3yDzvk=; h=Date:From:To:Subject:In-Reply-To:From; b=yST5V7MI6TNTixVOBVSzajv07c/mdva30cf8ICrAqeNy0vr7Y6pFAEH2d5z9Yk61p 9r2KpVxyew6Qtvb8IieCuynvzQauLE6/kuAyB+oE3OcWcbz5rflgcYdPYszIm4dtHH 9YrgrI7qbaXghDsM9HqRDrpAq0HPTvLdkWWcjRB4= Date: Thu, 20 Aug 2020 17:42:17 -0700 From: Andrew Morton To: akpm@linux-foundation.org, hughd@google.com, kirill.shutemov@linux.intel.com, linux-mm@kvack.org, mm-commits@vger.kernel.org, oleg@redhat.com, songliubraving@fb.com, srikar@linux.vnet.ibm.com, stable@vger.kernel.org, syzkaller@googlegroups.com, torvalds@linux-foundation.org Subject: [patch 08/11] uprobes: __replace_page() avoid BUG in munlock_vma_page() Message-ID: <20200821004217.UBGpf4I1N%akpm@linux-foundation.org> In-Reply-To: <20200820174132.67fd4a7a9359048f807a533b@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: mm-commits-owner@vger.kernel.org Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Hugh Dickins Subject: uprobes: __replace_page() avoid BUG in munlock_vma_page() syzbot crashed on the VM_BUG_ON_PAGE(PageTail) in munlock_vma_page(), when called from uprobes __replace_page(). Which of many ways to fix it? Settled on not calling when PageCompound (since Head and Tail are equals in this context, PageCompound the usual check in uprobes.c, and the prior use of FOLL_SPLIT_PMD will have cleared PageMlocked already). Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008161338360.20413@eggly.anvils Fixes: 5a52c9df62b4 ("uprobe: use FOLL_SPLIT_PMD instead of FOLL_SPLIT") Signed-off-by: Hugh Dickins Reported-by: syzbot Acked-by: Song Liu Acked-by: Oleg Nesterov Reviewed-by: Srikar Dronamraju Cc: "Kirill A. Shutemov" Cc: [5.4+] Signed-off-by: Andrew Morton --- kernel/events/uprobes.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/events/uprobes.c~uprobes-__replace_page-avoid-bug-in-munlock_vma_page +++ a/kernel/events/uprobes.c @@ -205,7 +205,7 @@ static int __replace_page(struct vm_area try_to_free_swap(old_page); page_vma_mapped_walk_done(&pvmw); - if (vma->vm_flags & VM_LOCKED) + if ((vma->vm_flags & VM_LOCKED) && !PageCompound(old_page)) munlock_vma_page(old_page); put_page(old_page); _