linux-kernel - Re: [PATCH] ALSA: hda - Handle kzalloc() failure in snd_hda_attach_pcm

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Date:   Fri, 01 Jun 2018 09:39:29 +0200
From:   Takashi Iwai <tiwai@...e.de>
To:     "Bo Chen" <chenbo@....edu>
Cc:     <alsa-devel@...a-project.org>, <perex@...ex.cz>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ALSA: hda - Handle kzalloc() failure in snd_hda_attach_pcm_stream()

On Fri, 01 Jun 2018 00:35:18 +0200,
Bo Chen wrote:
> 
> When 'kzalloc()' fails in 'snd_hda_attach_pcm_stream()', a new pcm instance is
> created without setting its operators via 'snd_pcm_set_ops()'. Following
> operations on the new pcm instance can trigger kernel null pointer dereferences
> and cause kernel oops.
> 
> This bug was found with my work on building a gray-box fault-injection tool for
> linux-kernel-module binaries. A kernel null pointer dereference was confirmed
> from line 'substream->ops->open()' in function 'snd_pcm_open_substream()' in
> file 'sound/core/pcm_native.c'.
> 
> This patch fixes the bug by calling 'snd_device_free()' in the error handling
> path of 'kzalloc()', which removes the new pcm instance from the snd card before
> returns with an error code.
> 
> Signed-off-by: Bo Chen <chenbo@....edu>

Applied now.  Thanks.


Takashi