From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CD9EE13AD0C; Thu, 11 Apr 2024 10:04:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712829840; cv=none; b=otIZ4mDCzMbOdMwkyLGprNhba4GmvzbInPUL+tfU44pG4yzlWLgsy4d00qpVWhjc9NI4N26bXZ0fqZZbhg2gsoBNthmEzErfnJ/Ml/FhVE0DL8BEz9pDYwpB1EuMcARHWcAyGuoeeW+8gbQS1G5ImOEDkuE6hVox+c16I+qhfLc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712829840; c=relaxed/simple; bh=+e5SNT9SOHY0UYEj/IviCuOMFBVulcchmjn4GPRBHiQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=O4mdcz+PLFT3uoPFlG5+FrFRkGd2yjNj5CcJiXqzZlKgofM0L8sZ3OUX3dV8vl+CZNI9dpMts+YRIUxwNacRFLaviNJsJuc9KTZqaJCSQgUU6tybqLsU2BLONyLXejARqt+sF2HE0JCGPYHkZ2LYJXM/dZ9Esf71H4MG3LlKENI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gRmAcuCv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="gRmAcuCv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 57830C433F1; Thu, 11 Apr 2024 10:04:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1712829840; bh=+e5SNT9SOHY0UYEj/IviCuOMFBVulcchmjn4GPRBHiQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gRmAcuCvNqIK88cjx3wFIe2l4Tx5JpCb73AJiceJdB+qRos21N75Mg+HL3LJIzO2y SNw2WkJt1FKcAEA8XHlNv6TNQT1hKdl6E9dW0Mq66qHOFrSEBK7gDBVumlT2VsLFUR GPTfneyubUXEnFKOuqfY+7+SCJHLjbIEd51irdHE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Takashi Iwai , Duoming Zhou Subject: [PATCH 4.19 085/175] ALSA: sh: aica: reorder cleanup operations to avoid UAF bugs Date: Thu, 11 Apr 2024 11:55:08 +0200 Message-ID: <20240411095422.120837037@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240411095419.532012976@linuxfoundation.org> References: <20240411095419.532012976@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Duoming Zhou commit 051e0840ffa8ab25554d6b14b62c9ab9e4901457 upstream. The dreamcastcard->timer could schedule the spu_dma_work and the spu_dma_work could also arm the dreamcastcard->timer. When the snd_pcm_substream is closing, the aica_channel will be deallocated. But it could still be dereferenced in the worker thread. The reason is that del_timer() will return directly regardless of whether the timer handler is running or not and the worker could be rescheduled in the timer handler. As a result, the UAF bug will happen. The racy situation is shown below: (Thread 1) | (Thread 2) snd_aicapcm_pcm_close() | ... | run_spu_dma() //worker | mod_timer() flush_work() | del_timer() | aica_period_elapsed() //timer kfree(dreamcastcard->channel) | schedule_work() | run_spu_dma() //worker ... | dreamcastcard->channel-> //USE In order to mitigate this bug and other possible corner cases, call mod_timer() conditionally in run_spu_dma(), then implement PCM sync_stop op to cancel both the timer and worker. The sync_stop op will be called from PCM core appropriately when needed. Fixes: 198de43d758c ("[ALSA] Add ALSA support for the SEGA Dreamcast PCM device") Suggested-by: Takashi Iwai Signed-off-by: Duoming Zhou Message-ID: <20240326094238.95442-1-duoming@zju.edu.cn> Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/sh/aica.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) --- a/sound/sh/aica.c +++ b/sound/sh/aica.c @@ -295,7 +295,8 @@ static void run_spu_dma(struct work_stru dreamcastcard->clicks++; if (unlikely(dreamcastcard->clicks >= AICA_PERIOD_NUMBER)) dreamcastcard->clicks %= AICA_PERIOD_NUMBER; - mod_timer(&dreamcastcard->timer, jiffies + 1); + if (snd_pcm_running(dreamcastcard->substream)) + mod_timer(&dreamcastcard->timer, jiffies + 1); } } @@ -307,6 +308,8 @@ static void aica_period_elapsed(struct t /*timer function - so cannot sleep */ int play_period; struct snd_pcm_runtime *runtime; + if (!snd_pcm_running(substream)) + return; runtime = substream->runtime; dreamcastcard = substream->pcm->private_data; /* Have we played out an additional period? */ @@ -367,12 +370,19 @@ static int snd_aicapcm_pcm_open(struct s return 0; } +static int snd_aicapcm_pcm_sync_stop(struct snd_pcm_substream *substream) +{ + struct snd_card_aica *dreamcastcard = substream->pcm->private_data; + + del_timer_sync(&dreamcastcard->timer); + cancel_work_sync(&dreamcastcard->spu_dma_work); + return 0; +} + static int snd_aicapcm_pcm_close(struct snd_pcm_substream *substream) { struct snd_card_aica *dreamcastcard = substream->pcm->private_data; - flush_work(&(dreamcastcard->spu_dma_work)); - del_timer(&dreamcastcard->timer); dreamcastcard->substream = NULL; kfree(dreamcastcard->channel); spu_disable(); @@ -438,6 +448,7 @@ static const struct snd_pcm_ops snd_aica .prepare = snd_aicapcm_pcm_prepare, .trigger = snd_aicapcm_pcm_trigger, .pointer = snd_aicapcm_pcm_pointer, + .sync_stop = snd_aicapcm_pcm_sync_stop, }; /* TO DO: set up to handle more than one pcm instance */