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 6958BC433EF for ; Sat, 23 Jul 2022 14:04:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237318AbiGWOEY (ORCPT ); Sat, 23 Jul 2022 10:04:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41256 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236970AbiGWOEW (ORCPT ); Sat, 23 Jul 2022 10:04:22 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93BA317070; Sat, 23 Jul 2022 07:04:21 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 2F6F76142E; Sat, 23 Jul 2022 14:04:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C049C341C0; Sat, 23 Jul 2022 14:04:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658585060; bh=i1hxM7Ujsdhm0k5s+lkC/ZUWIW+MTz2oWW+dSJcQLC8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bM4kEy1UjIF7GQ2Cqma5PvVIa4l9Ycx641e8SXLbUQjuzhfNV56YWb8GsGgVDVbPn UD+qsJz0rlBCL23S82Ol4/5NHIVKM6lLBE8KEJ2VpZm0LZwd7qrTvDEcnFQqXYNB0T M8EUJwv32dszihD48D1JbVOhmHUcB4tpWGYhCUPM= Date: Sat, 23 Jul 2022 16:04:17 +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: X-Mailing-List: linux-kernel@vger.kernel.org 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(); Also you now have a spinlock held when calling rcu_read_unlock(), are you sure that's ok? 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 smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3A166C433EF for ; Sat, 23 Jul 2022 14:04:28 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id D41F541868; Sat, 23 Jul 2022 14:04:27 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp4.osuosl.org D41F541868 Authentication-Results: smtp4.osuosl.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=bM4kEy1U X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id di6YYqFBxVPG; Sat, 23 Jul 2022 14:04:26 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp4.osuosl.org (Postfix) with ESMTPS id 9BC8E416CD; Sat, 23 Jul 2022 14:04:26 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp4.osuosl.org 9BC8E416CD Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6A9FBC0033; Sat, 23 Jul 2022 14:04:26 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id B2E40C002D for ; Sat, 23 Jul 2022 14:04:24 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id 7CBFC8496C for ; Sat, 23 Jul 2022 14:04:24 +0000 (UTC) DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 7CBFC8496C Authentication-Results: smtp1.osuosl.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=bM4kEy1U X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id U722g4Y3BBNJ for ; Sat, 23 Jul 2022 14:04:23 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.8.0 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp1.osuosl.org 99ADA83218 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by smtp1.osuosl.org (Postfix) with ESMTPS id 99ADA83218 for ; Sat, 23 Jul 2022 14:04:23 +0000 (UTC) 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 F1752B8092D; Sat, 23 Jul 2022 14:04:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C049C341C0; Sat, 23 Jul 2022 14:04:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658585060; bh=i1hxM7Ujsdhm0k5s+lkC/ZUWIW+MTz2oWW+dSJcQLC8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=bM4kEy1UjIF7GQ2Cqma5PvVIa4l9Ycx641e8SXLbUQjuzhfNV56YWb8GsGgVDVbPn UD+qsJz0rlBCL23S82Ol4/5NHIVKM6lLBE8KEJ2VpZm0LZwd7qrTvDEcnFQqXYNB0T M8EUJwv32dszihD48D1JbVOhmHUcB4tpWGYhCUPM= Date: Sat, 23 Jul 2022 16:04:17 +0200 From: Greg KH To: Siddh Raman Pant 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-Disposition: inline In-Reply-To: <20220723135447.199557-1-code@siddh.me> Cc: syzbot+c70d87ac1d001f29a058@syzkaller.appspotmail.com, linux-kernel-mentees , linux-security-modules , linux-kernel , David Howells , Eric Dumazet , Christophe JAILLET , "Fabio M. De Francesco" X-BeenThere: linux-kernel-mentees@lists.linuxfoundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-kernel-mentees-bounces@lists.linuxfoundation.org Sender: "Linux-kernel-mentees" 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(); Also you now have a spinlock held when calling rcu_read_unlock(), are you sure that's ok? _______________________________________________ Linux-kernel-mentees mailing list Linux-kernel-mentees@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/linux-kernel-mentees