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 6F6AAC77B7A for ; Wed, 7 Jun 2023 20:55:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235476AbjFGUzl (ORCPT ); Wed, 7 Jun 2023 16:55:41 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56738 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235439AbjFGUzk (ORCPT ); Wed, 7 Jun 2023 16:55:40 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A506895 for ; Wed, 7 Jun 2023 13:55:38 -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 397326481E for ; Wed, 7 Jun 2023 20:55:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4E880C4339B; Wed, 7 Jun 2023 20:55:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1686171337; bh=V6Qe5K1QN9D8bDEoRk94m8xGFrxEn6EKWIgVEI2ErEM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E9LDhHnL2cBhPrrkrwjwNUr+s+5u0GUknlUM2yeBxkklbDbxdhWd+DRLUw1GdxB9T dTcOvsRmRXX/ibT9PtdYNaZCx1nZgRFoM/N0k4aOVGM5NxdK7uRZlP7/nyaYOxPR2W 9TI7hWOfGgcXhdImhWDMZwOoDToIR5kHRbGRN7ms= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yu Hao , Takashi Iwai , Mauro Carvalho Chehab , Sasha Levin Subject: [PATCH 5.4 50/99] media: dvb-core: Fix kernel WARNING for blocking operation in wait_event*() Date: Wed, 7 Jun 2023 22:16:42 +0200 Message-ID: <20230607200901.815081759@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230607200900.195572674@linuxfoundation.org> References: <20230607200900.195572674@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Takashi Iwai [ Upstream commit b8c75e4a1b325ea0a9433fa8834be97b5836b946 ] Using a semaphore in the wait_event*() condition is no good idea. It hits a kernel WARN_ON() at prepare_to_wait_event() like: do not call blocking ops when !TASK_RUNNING; state=1 set at prepare_to_wait_event+0x6d/0x690 For avoiding the potential deadlock, rewrite to an open-coded loop instead. Unlike the loop in wait_event*(), this uses wait_woken() after the condition check, hence the task state stays consistent. CVE-2023-31084 was assigned to this bug. Link: https://lore.kernel.org/r/CA+UBctCu7fXn4q41O_3=id1+OdyQ85tZY1x+TkT-6OVBL6KAUw@mail.gmail.com/ Link: https://lore.kernel.org/linux-media/20230512151800.1874-1-tiwai@suse.de Reported-by: Yu Hao Closes: https://nvd.nist.gov/vuln/detail/CVE-2023-31084 Signed-off-by: Takashi Iwai Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin --- drivers/media/dvb-core/dvb_frontend.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/media/dvb-core/dvb_frontend.c b/drivers/media/dvb-core/dvb_frontend.c index b04638321b75b..ad3e42a4eaf73 100644 --- a/drivers/media/dvb-core/dvb_frontend.c +++ b/drivers/media/dvb-core/dvb_frontend.c @@ -292,14 +292,22 @@ static int dvb_frontend_get_event(struct dvb_frontend *fe, } if (events->eventw == events->eventr) { - int ret; + struct wait_queue_entry wait; + int ret = 0; if (flags & O_NONBLOCK) return -EWOULDBLOCK; - ret = wait_event_interruptible(events->wait_queue, - dvb_frontend_test_event(fepriv, events)); - + init_waitqueue_entry(&wait, current); + add_wait_queue(&events->wait_queue, &wait); + while (!dvb_frontend_test_event(fepriv, events)) { + wait_woken(&wait, TASK_INTERRUPTIBLE, 0); + if (signal_pending(current)) { + ret = -ERESTARTSYS; + break; + } + } + remove_wait_queue(&events->wait_queue, &wait); if (ret < 0) return ret; } -- 2.39.2