From nobody Wed Apr 15 07:00:16 2026 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 35516C433EF for ; Sat, 23 Jul 2022 13:57:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233517AbiGWN5m (ORCPT ); Sat, 23 Jul 2022 09:57:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37038 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229760AbiGWN5j (ORCPT ); Sat, 23 Jul 2022 09:57:39 -0400 X-Greylist: delayed 340 seconds by postgrey-1.37 at lindbergh.monkeyblade.net; Sat, 23 Jul 2022 06:57:38 PDT Received: from sender-of-o53.zoho.in (sender-of-o53.zoho.in [103.117.158.53]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 17B931A397; Sat, 23 Jul 2022 06:57:37 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1658584631; cv=none; d=zohomail.in; s=zohoarc; b=R9dbIFc1ASVJ9R34cbOfYzXoARqki1ZPvuRVpM4LJ/uWcDrzYgRRfR2ygb+ykBXgnpVzSCyZGPkZLozYWups1guJmNmRdNbTFz/pnrr1ytekq14hpRefLCR06ibCUDFhMA8NuBK+cxL88yiDTqkcyg38hUaSB29jl4EXHXj9bS4= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.in; s=zohoarc; t=1658584631; h=Content-Type:Content-Transfer-Encoding:Cc:Date:From:MIME-Version:Message-ID:Subject:To; bh=8L4SM4wJh/annJul/rPP0P8kFy0c6pBphS7E4f99Zxw=; b=FY2CfHGUEizRbQmYUjGiV5OVrPCX8GidwKBP8KBmhTY6Ol5Nnoi4aNQx7fMW4F1O8A6Uf10z+JVk1jDZfDWxnoUjB7nwUb0EQWu8heTAoZKYlKimbld0bNzgAi0Nulb9IrrGTeq9/R5bdz8Ni7vKdaAs3WQf6H8BGofoeL1oCqg= ARC-Authentication-Results: i=1; mx.zohomail.in; dkim=pass header.i=siddh.me; spf=pass smtp.mailfrom=code@siddh.me; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1658584631; s=zmail; d=siddh.me; i=code@siddh.me; h=From:From:To:To:Cc:Cc:Message-ID:Subject:Subject:Date:Date:MIME-Version:Content-Transfer-Encoding:Content-Type:Message-Id:Reply-To; bh=8L4SM4wJh/annJul/rPP0P8kFy0c6pBphS7E4f99Zxw=; b=W2LzvKrxqDsIgR7clEFkfAgceQV7UP8aH2pplFvqPzBpQWdcyI+ebtJbamdvRuQH 7BlUbSLLb/aYOLX7qjoRrmjvgrecUn6VxwBpFPc3dFJVceF2peCcKW32rsRjItX5OgT 1UuMaEW2un8UgomefCzWk/ckyHj34V8sR+jTbKnc= Received: from localhost.localdomain (43.250.158.127 [43.250.158.127]) by mx.zoho.in with SMTPS id 1658584630365731.3156260741329; Sat, 23 Jul 2022 19:27:10 +0530 (IST) From: Siddh Raman Pant To: David Howells , Christophe JAILLET , Eric Dumazet , "Fabio M. De Francesco" Cc: linux-security-modules , linux-kernel , linux-kernel-mentees , syzbot+c70d87ac1d001f29a058@syzkaller.appspotmail.com Message-ID: <20220723135447.199557-1-code@siddh.me> Subject: [PATCH] kernel/watch_queue: Make pipe NULL while clearing watch_queue Date: Sat, 23 Jul 2022 19:24:47 +0530 X-Mailer: git-send-email 2.35.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMailClient: External Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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=3D1870dd7791ba05f2ea7f47f7= cbdde701173973fc Reported-and-tested-by: syzbot+c70d87ac1d001f29a058@syzkaller.appspotmail.c= om 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); } =20 - spin_unlock_bh(&wqueue->lock); rcu_read_unlock(); + + /* Clearing the watch queue, so we should clean the associated pipe. */ +#ifdef CONFIG_WATCH_QUEUE + if (wqueue->pipe) { + wqueue->pipe->watch_queue =3D NULL; + wqueue->pipe =3D NULL; + } +#endif + + spin_unlock_bh(&wqueue->lock); } =20 /** --=20 2.35.1