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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 A7960C433F5 for ; Mon, 20 Sep 2021 18:25:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9091461284 for ; Mon, 20 Sep 2021 18:25:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352251AbhITS0w (ORCPT ); Mon, 20 Sep 2021 14:26:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:43180 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377693AbhITSUT (ORCPT ); Mon, 20 Sep 2021 14:20:19 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7B65D632AA; Mon, 20 Sep 2021 17:23:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1632158610; bh=t2iXuvRApkXkndxKEFV8qBh7oCRTavfhVfmUtTDE7LU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CeqZSUeDrk+lxF243lVVkSTdIgTib5rbGTYvn1qsjD44l8rM73+u6mvTAmylD/W5M fFCZ3KUcwGO0dDyXhqehn/qLU2rUiXvN01YMQi9gnvAFVyGDtWd8meIWTsMFUjU035 97RJBgewkRAnPY610agz2g//isJnwYX/hw+FTt2Y= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, lijiazi , Miklos Szeredi , Sasha Levin Subject: [PATCH 5.4 236/260] fuse: fix use after free in fuse_read_interrupt() Date: Mon, 20 Sep 2021 18:44:14 +0200 Message-Id: <20210920163939.145541437@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210920163931.123590023@linuxfoundation.org> References: <20210920163931.123590023@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Miklos Szeredi [ Upstream commit e1e71c168813564be0f6ea3d6740a059ca42d177 ] There is a potential race between fuse_read_interrupt() and fuse_request_end(). TASK1 in fuse_read_interrupt(): delete req->intr_entry (while holding fiq->lock) TASK2 in fuse_request_end(): req->intr_entry is empty -> skip fiq->lock wake up TASK3 TASK3 request is freed TASK1 in fuse_read_interrupt(): dereference req->in.h.unique ***BAM*** Fix by always grabbing fiq->lock if the request was ever interrupted (FR_INTERRUPTED set) thereby serializing with concurrent fuse_read_interrupt() calls. FR_INTERRUPTED is set before the request is queued on fiq->interrupts. Dequeing the request is done with list_del_init() but FR_INTERRUPTED is not cleared in this case. Reported-by: lijiazi Signed-off-by: Miklos Szeredi Signed-off-by: Sasha Levin --- fs/fuse/dev.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 16aa55b73ccf..7205a89fbb5f 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -282,10 +282,10 @@ void fuse_request_end(struct fuse_conn *fc, struct fuse_req *req) /* * test_and_set_bit() implies smp_mb() between bit - * changing and below intr_entry check. Pairs with + * changing and below FR_INTERRUPTED check. Pairs with * smp_mb() from queue_interrupt(). */ - if (!list_empty(&req->intr_entry)) { + if (test_bit(FR_INTERRUPTED, &req->flags)) { spin_lock(&fiq->lock); list_del_init(&req->intr_entry); spin_unlock(&fiq->lock); -- 2.30.2