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=-10.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 27E32C2BB1D for ; Wed, 8 Apr 2020 01:40:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0ECF206F7 for ; Wed, 8 Apr 2020 01:40:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="HZhDpk9r" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726620AbgDHBk1 (ORCPT ); Tue, 7 Apr 2020 21:40:27 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:43798 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726436AbgDHBkZ (ORCPT ); Tue, 7 Apr 2020 21:40:25 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1586310024; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=fSQbrEAc+w70rT9qB0nDUcFBa4qHjfjCBhj2Rky49/o=; b=HZhDpk9rshQ3k2xMQGU3BjYCE1tGhC6fEHLJ1prJ1ujQrBpPTH+W/8SRnUfcpP5zJRrJXH v6sw/cS6K06PqRvuzUtqCeTyfwi5b4YYdvkW1hjDesSsIWsLPM7yPihVLbDNglCI3EODjH OTfSpIP72EXhzjHjGoJNa3gP6FZiiUY= Received: from mail-qt1-f197.google.com (mail-qt1-f197.google.com [209.85.160.197]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-310-bHa42HK9PH-3ujoxNQ8rRQ-1; Tue, 07 Apr 2020 21:40:23 -0400 X-MC-Unique: bHa42HK9PH-3ujoxNQ8rRQ-1 Received: by mail-qt1-f197.google.com with SMTP id z5so5014396qtd.4 for ; Tue, 07 Apr 2020 18:40:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=fSQbrEAc+w70rT9qB0nDUcFBa4qHjfjCBhj2Rky49/o=; b=KVx/qsv95Qr7EA9+0Q5uumKlxEgysfmWiYyc28OiQX+m55o5ciNJP/kNdc1QWHnm+D 4gajE7qbJmPqKlhBZL5xd7Fcn7fpQU/CyZ8PFLIj7HWt4y8bcm+aAkTh486/qU+Nlpk0 sN6M58zMxrAQc9CIi7lv3WQnc/bproRBoBM9PUSXbhSRC5DQj4luVCK+bOJiYBgUPlUn DnpQ48+fWi6r+fc42kPOfMh4m/x7r0i/QNmHwQKlR24tCIUOLBEKz7UZI3VRMmwwBfg3 Nkjhk8owIWVLKiMzEyciOJBGVfPuPLniyU1yBle6jcsjqywAdyzNGAwOBQePiMtKHxHX 0hMw== X-Gm-Message-State: AGi0PuYhxhvVl1Q9VPHovJMMeAZfUKGXJavrCR1+VG1nTcy4o8tGwVMh hlPN+8I13ueaJnqzoFK9KmFprLYJfvB7FzGvRVLZw0Tqwwjfkic3Cauf0/SMfTKqEEuoLSZTq8z UoxG7g+2+hePpwP0MdrwwfAsk X-Received: by 2002:aed:3b4c:: with SMTP id q12mr5171839qte.18.1586310022101; Tue, 07 Apr 2020 18:40:22 -0700 (PDT) X-Google-Smtp-Source: APiQypKjaxC86ETeSiD0L0Kj0V5llgsE6iR778Jm5S9I3k5ubB9PlpALIp3ITqh0ujLQ2viwPE/E4Q== X-Received: by 2002:aed:3b4c:: with SMTP id q12mr5171819qte.18.1586310021884; Tue, 07 Apr 2020 18:40:21 -0700 (PDT) Received: from xz-x1.hitronhub.home ([2607:9880:19c0:32::3]) by smtp.gmail.com with ESMTPSA id x24sm6126607qth.80.2020.04.07.18.40.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Apr 2020 18:40:18 -0700 (PDT) From: Peter Xu To: linux-kernel@vger.kernel.org, Linus Torvalds , linux-mm@kvack.org Cc: Andrew Morton , peterx@redhat.com, syzbot+a8c70b7f3579fc0587dc@syzkaller.appspotmail.com Subject: [PATCH 2/2] mm/gup: Mark lock taken only after a successful retake Date: Tue, 7 Apr 2020 21:40:10 -0400 Message-Id: <20200408014010.80428-3-peterx@redhat.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200408014010.80428-1-peterx@redhat.com> References: <20200408014010.80428-1-peterx@redhat.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 It's definitely incorrect to mark the lock as taken even if down_read_killable() failed. It's overlooked when we switched from down_read() to down_read_killable() because down_read() won't fail while down_read_killable() could. Reported-by: syzbot+a8c70b7f3579fc0587dc@syzkaller.appspotmail.com Fixes: 71335f37c5e8 ("mm/gup: allow to react to fatal signals") Signed-off-by: Peter Xu --- mm/gup.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/gup.c b/mm/gup.c index da3e03185144..1f9a9b3a5869 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -1328,7 +1328,6 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk, if (fatal_signal_pending(current)) break; - *locked = 1; ret = down_read_killable(&mm->mmap_sem); if (ret) { BUG_ON(ret > 0); @@ -1337,6 +1336,7 @@ static __always_inline long __get_user_pages_locked(struct task_struct *tsk, break; } + *locked = 1; ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED, pages, NULL, locked); if (!*locked) { -- 2.24.1