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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Takashi Iwai <tiwai@suse.de>,
	syzbot+e1fe9f44fb8ecf4fb5dd@syzkaller.appspotmail.com,
	Sasha Levin <sashal@kernel.org>,
	alsa-devel@alsa-project.org
Subject: [PATCH AUTOSEL 5.4 15/19] ALSA: pcm: oss: Avoid plugin buffer overflow
Date: Thu, 26 Mar 2020 19:24:27 -0400
Message-ID: <20200326232431.7816-15-sashal@kernel.org> (raw)
In-Reply-To: <20200326232431.7816-1-sashal@kernel.org>

From: Takashi Iwai <tiwai@suse.de>

[ Upstream commit f2ecf903ef06eb1bbbfa969db9889643d487e73a ]

Each OSS PCM plugins allocate its internal buffer per pre-calculation
of the max buffer size through the chain of plugins (calling
src_frames and dst_frames callbacks).  This works for most plugins,
but the rate plugin might behave incorrectly.  The calculation in the
rate plugin involves with the fractional position, i.e. it may vary
depending on the input position.  Since the buffer size
pre-calculation is always done with the offset zero, it may return a
shorter size than it might be; this may result in the out-of-bound
access as spotted by fuzzer.

This patch addresses those possible buffer overflow accesses by simply
setting the upper limit per the given buffer size for each plugin
before src_frames() and after dst_frames() calls.

Reported-by: syzbot+e1fe9f44fb8ecf4fb5dd@syzkaller.appspotmail.com
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/000000000000b25ea005a02bcf21@google.com
Link: https://lore.kernel.org/r/20200309082148.19855-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 sound/core/oss/pcm_plugin.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/sound/core/oss/pcm_plugin.c b/sound/core/oss/pcm_plugin.c
index 31cb2acf8afcc..9b588c6a6f099 100644
--- a/sound/core/oss/pcm_plugin.c
+++ b/sound/core/oss/pcm_plugin.c
@@ -209,6 +209,8 @@ snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *plug, snd_p
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		plugin = snd_pcm_plug_last(plug);
 		while (plugin && drv_frames > 0) {
+			if (drv_frames > plugin->buf_frames)
+				drv_frames = plugin->buf_frames;
 			plugin_prev = plugin->prev;
 			if (plugin->src_frames)
 				drv_frames = plugin->src_frames(plugin, drv_frames);
@@ -220,6 +222,8 @@ snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *plug, snd_p
 			plugin_next = plugin->next;
 			if (plugin->dst_frames)
 				drv_frames = plugin->dst_frames(plugin, drv_frames);
+			if (drv_frames > plugin->buf_frames)
+				drv_frames = plugin->buf_frames;
 			plugin = plugin_next;
 		}
 	} else
@@ -248,11 +252,15 @@ snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *plug, snd_pc
 				if (frames < 0)
 					return frames;
 			}
+			if (frames > plugin->buf_frames)
+				frames = plugin->buf_frames;
 			plugin = plugin_next;
 		}
 	} else if (stream == SNDRV_PCM_STREAM_CAPTURE) {
 		plugin = snd_pcm_plug_last(plug);
 		while (plugin) {
+			if (frames > plugin->buf_frames)
+				frames = plugin->buf_frames;
 			plugin_prev = plugin->prev;
 			if (plugin->src_frames) {
 				frames = plugin->src_frames(plugin, frames);
-- 
2.20.1


  parent reply index

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-26 23:24 [PATCH AUTOSEL 5.4 01/19] drm/bridge: dw-hdmi: fix AVI frame colorimetry Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 02/19] nvme-rdma: Avoid double freeing of async event data Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 03/19] ALSA: hda/realtek: Fix pop noise on ALC225 Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 04/19] kconfig: introduce m32-flag and m64-flag Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 05/19] drm/amd/display: Add link_rate quirk for Apple 15" MBP 2017 Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 06/19] drm/bochs: downgrade pci_request_region failure from error to warning Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 07/19] initramfs: restore default compression behavior Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 08/19] staging: greybus: loopback_test: fix potential path truncation Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 09/19] staging: greybus: loopback_test: fix potential path truncations Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 10/19] drm/amdgpu: fix typo for vcn1 idle check Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 11/19] tools/power turbostat: Fix gcc build warnings Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 12/19] tools/power turbostat: Fix missing SYS_LPI counter on some Chromebooks Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 13/19] tools/power turbostat: Fix 32-bit capabilities warning Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 14/19] nvmet-tcp: set MSG_MORE only if we actually have more to send Sasha Levin
2020-03-26 23:24 ` Sasha Levin [this message]
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 16/19] ALSA: line6: Fix endless MIDI read loop Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 17/19] ALSA: pcm: oss: Remove WARNING from snd_pcm_plug_alloc() checks Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 18/19] tty: fix compat TIOCGSERIAL leaking uninitialized memory Sasha Levin
2020-03-26 23:24 ` [PATCH AUTOSEL 5.4 19/19] drm/lease: fix WARNING in idr_destroy Sasha Levin

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