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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BEF9AC4332F for ; Mon, 18 Oct 2021 13:51:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AD39E61356 for ; Mon, 18 Oct 2021 13:51:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232688AbhJRNyI (ORCPT ); Mon, 18 Oct 2021 09:54:08 -0400 Received: from mail.kernel.org ([198.145.29.99]:49552 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232135AbhJRNvV (ORCPT ); Mon, 18 Oct 2021 09:51:21 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 30ECB61881; Mon, 18 Oct 2021 13:38:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1634564287; bh=6eDWqturCmIhUGp+VhapVzWSFy+VSIdEuKRe4eOMXrs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cFatlLCm1jd6Exn8QACLvRboKjI1x1OfONGBNbPBQKWu2gwi0/+ryshHFx+vPy7KN zJOIE5QJc0M0L9VZXKHc+AGhtLzWe+/gQ+Dzhj0N4kLeSLylie33k2voZl1C4hvPJM 5sFR1ZnmVvYYkn7t//NZ/51yNDQG81FWg/aEiYwY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Takashi Iwai , John Keeping Subject: [PATCH 5.14 004/151] ALSA: seq: Fix a potential UAF by wrong private_free call order Date: Mon, 18 Oct 2021 15:23:03 +0200 Message-Id: <20211018132340.829520377@linuxfoundation.org> X-Mailer: git-send-email 2.33.1 In-Reply-To: <20211018132340.682786018@linuxfoundation.org> References: <20211018132340.682786018@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: Takashi Iwai commit 1f8763c59c4ec6254d629fe77c0a52220bd907aa upstream. John Keeping reported and posted a patch for a potential UAF in rawmidi sequencer destruction: the snd_rawmidi_dev_seq_free() may be called after the associated rawmidi object got already freed. After a deeper look, it turned out that the bug is rather the incorrect private_free call order for a snd_seq_device. The snd_seq_device private_free gets called at the release callback of the sequencer device object, while this was rather expected to be executed at the snd_device call chains that runs at the beginning of the whole card-free procedure. It's been broken since the rewrite of sequencer-device binding (although it hasn't surfaced because the sequencer device release happens usually right along with the card device release). This patch corrects the private_free call to be done in the right place, at snd_seq_device_dev_free(). Fixes: 7c37ae5c625a ("ALSA: seq: Rewrite sequencer device binding with standard bus") Reported-and-tested-by: John Keeping Cc: Link: https://lore.kernel.org/r/20210930114114.8645-1-tiwai@suse.de Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/core/seq_device.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-) --- a/sound/core/seq_device.c +++ b/sound/core/seq_device.c @@ -156,6 +156,8 @@ static int snd_seq_device_dev_free(struc struct snd_seq_device *dev = device->device_data; cancel_autoload_drivers(); + if (dev->private_free) + dev->private_free(dev); put_device(&dev->dev); return 0; } @@ -183,11 +185,7 @@ static int snd_seq_device_dev_disconnect static void snd_seq_dev_release(struct device *dev) { - struct snd_seq_device *sdev = to_seq_dev(dev); - - if (sdev->private_free) - sdev->private_free(sdev); - kfree(sdev); + kfree(to_seq_dev(dev)); } /*