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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0BC5CC43334 for ; Sat, 23 Jul 2022 14:03:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236274AbiGWODv (ORCPT ); Sat, 23 Jul 2022 10:03:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40694 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236970AbiGWODl (ORCPT ); Sat, 23 Jul 2022 10:03:41 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 67E7118352; Sat, 23 Jul 2022 07:03:39 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 27411B80933; Sat, 23 Jul 2022 14:03:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 446A9C341C0; Sat, 23 Jul 2022 14:03:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658585016; bh=XqGMGbWcq/P/xI62FKVCA6GKm6TlYQEjhChvhcH8c6c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=2v4Ogmb1fTi6SwT/Cl8Yh7GOWTfgYMWnRtwFzv4NkzAvLBEQ4id717IHS/adN5rmh ScFUmUAENhzejbd4i51Tmupu3c2iNmwZxV75dfibaN3amEb+eP2d10ZlngTPGZVDpV tHnNtGv970qVPIm8c6jnOVFxSNJyNyM8ylAXKHOA= Date: Sat, 23 Jul 2022 16:03:33 +0200 From: Greg KH To: Siddh Raman Pant Cc: David Howells , Christophe JAILLET , Eric Dumazet , "Fabio M. De Francesco" , linux-security-modules , linux-kernel-mentees , linux-kernel , syzbot+c70d87ac1d001f29a058@syzkaller.appspotmail.com Subject: Re: [PATCH] kernel/watch_queue: Make pipe NULL while clearing watch_queue Message-ID: References: <20220723135447.199557-1-code@siddh.me> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220723135447.199557-1-code@siddh.me> Precedence: bulk List-ID: On Sat, Jul 23, 2022 at 07:24:47PM +0530, Siddh Raman Pant via Linux-kernel-mentees wrote: > If not done, a reference to a freed pipe remains in the watch_queue, > as this function is called before freeing a pipe in free_pipe_info() > (see line 834 of fs/pipe.c). > > This causes a UAF when post_one_notification tries to access the pipe on > a key update, which is reported by syzbot. > > Bug report: https://syzkaller.appspot.com/bug?id=1870dd7791ba05f2ea7f47f7cbdde701173973fc > Reported-and-tested-by: syzbot+c70d87ac1d001f29a058@syzkaller.appspotmail.com > > Signed-off-by: Siddh Raman Pant > --- > kernel/watch_queue.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/kernel/watch_queue.c b/kernel/watch_queue.c > index bb9962b33f95..bab9e09c74cf 100644 > --- a/kernel/watch_queue.c > +++ b/kernel/watch_queue.c > @@ -637,8 +637,17 @@ void watch_queue_clear(struct watch_queue *wqueue) > spin_lock_bh(&wqueue->lock); > } > > - spin_unlock_bh(&wqueue->lock); > rcu_read_unlock(); > + > + /* Clearing the watch queue, so we should clean the associated pipe. */ > +#ifdef CONFIG_WATCH_QUEUE You should not use #ifdef in .c files, it's unmaintainable over time. thanks, greg k-h