Commit 1ae14cec authored by Takashi Iwai's avatar Takashi Iwai Committed by Jinjiang Tu
Browse files

ALSA: oss: Fix PCM OSS buffer allocation overflow 

stable inclusion
from stable-v4.19.237
commit a63af1baf0a5e11827db60e3127f87e437cab6e5
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBP1SP
CVE: CVE-2022-49292

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=a63af1baf0a5e11827db60e3127f87e437cab6e5



--------------------------------

commit efb6402c upstream.

We've got syzbot reports hitting INT_MAX overflow at vmalloc()
allocation that is called from snd_pcm_plug_alloc().  Although we
apply the restrictions to input parameters, it's based only on the
hw_params of the underlying PCM device.  Since the PCM OSS layer
allocates a temporary buffer for the data conversion, the size may
become unexpectedly large when more channels or higher rates is given;
in the reported case, it went over INT_MAX, hence it hits WARN_ON().

This patch is an attempt to avoid such an overflow and an allocation
for too large buffers.  First off, it adds the limit of 1MB as the
upper bound for period bytes.  This must be large enough for all use
cases, and we really don't want to handle a larger temporary buffer
than this size.  The size check is performed at two places, where the
original period bytes is calculated and where the plugin buffer size
is calculated.

In addition, the driver uses array_size() and array3_size() for
multiplications to catch overflows for the converted period size and
buffer bytes.

Reported-by: default avatar <syzbot+72732c532ac1454eeee9@syzkaller.appspotmail.com>
Suggested-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/00000000000085b1b305da5a66f3@google.com
Link: https://lore.kernel.org/r/20220318082036.29699-1-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarJinjiang Tu <tujinjiang@huawei.com>
parent 3e8e3ea7

sound/core/oss/pcm_oss.c

+8 −4
Original line number Diff line number Diff line
@@ -789,6 +789,11 @@ static int snd_pcm_oss_period_size(struct snd_pcm_substream *substream, 


	if (oss_period_size < 16)

		return -EINVAL;



	/* don't allocate too large period; 1MB period must be enough */

	if (oss_period_size > 1024 * 1024)

		return -ENOMEM;



	runtime->oss.period_bytes = oss_period_size;

	runtime->oss.period_frames = 1;

	runtime->oss.periods = oss_periods;
@@ -1053,10 +1058,9 @@ static int snd_pcm_oss_change_params_locked(struct snd_pcm_substream *substream) 
			goto failure;

	}

#endif

	oss_period_size *= oss_frame_size;



	oss_buffer_size = oss_period_size * runtime->oss.periods;

	if (oss_buffer_size < 0) {

	oss_period_size = array_size(oss_period_size, oss_frame_size);

	oss_buffer_size = array_size(oss_period_size, runtime->oss.periods);

	if (oss_buffer_size <= 0) {

		err = -EINVAL;

		goto failure;

	}

sound/core/oss/pcm_plugin.c

+4 −1
Original line number Diff line number Diff line
@@ -61,7 +61,10 @@ static int snd_pcm_plugin_alloc(struct snd_pcm_plugin *plugin, snd_pcm_uframes_t 
	}

	if ((width = snd_pcm_format_physical_width(format->format)) < 0)

		return width;

	size = frames * format->channels * width;

	size = array3_size(frames, format->channels, width);

	/* check for too large period size once again */

	if (size > 1024 * 1024)

		return -ENOMEM;

	if (snd_BUG_ON(size % 8))

		return -ENXIO;

	size /= 8;