[PATCH 5.4 23/57] ALSA: pcm: oss: Place the plugin buffer overflow checks correctly

[Greg Kroah-Hartman]

From: Takashi Iwai <tiwai@xxxxxxx>

commit 4285de0725b1bf73608abbcd35ad7fd3ddc0b61e upstream.

The checks of the plugin buffer overflow in the previous fix by commit
  f2ecf903ef06 ("ALSA: pcm: oss: Avoid plugin buffer overflow")
are put in the wrong places mistakenly, which leads to the expected
(repeated) sound when the rate plugin is involved.  Fix in the right
places.

Also, at those right places, the zero check is needed for the
termination node, so added there as well, and let's get it done,
finally.

Fixes: f2ecf903ef06 ("ALSA: pcm: oss: Avoid plugin buffer overflow")
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20200424193350.19678-1-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 sound/core/oss/pcm_plugin.c |   20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

--- a/sound/core/oss/pcm_plugin.c
+++ b/sound/core/oss/pcm_plugin.c
@@ -211,21 +211,23 @@ static snd_pcm_sframes_t plug_client_siz
 	if (stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		plugin = snd_pcm_plug_last(plug);
 		while (plugin && drv_frames > 0) {
-			if (check_size && 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);
+			if (check_size && plugin->buf_frames &&
+			    drv_frames > plugin->buf_frames)
+				drv_frames = plugin->buf_frames;
 			plugin = plugin_prev;
 		}
 	} else if (stream == SNDRV_PCM_STREAM_CAPTURE) {
 		plugin = snd_pcm_plug_first(plug);
 		while (plugin && drv_frames > 0) {
 			plugin_next = plugin->next;
+			if (check_size && plugin->buf_frames &&
+			    drv_frames > plugin->buf_frames)
+				drv_frames = plugin->buf_frames;
 			if (plugin->dst_frames)
 				drv_frames = plugin->dst_frames(plugin, drv_frames);
-			if (check_size && drv_frames > plugin->buf_frames)
-				drv_frames = plugin->buf_frames;
 			plugin = plugin_next;
 		}
 	} else
@@ -251,26 +253,28 @@ static snd_pcm_sframes_t plug_slave_size
 		plugin = snd_pcm_plug_first(plug);
 		while (plugin && frames > 0) {
 			plugin_next = plugin->next;
+			if (check_size && plugin->buf_frames &&
+			    frames > plugin->buf_frames)
+				frames = plugin->buf_frames;
 			if (plugin->dst_frames) {
 				frames = plugin->dst_frames(plugin, frames);
 				if (frames < 0)
 					return frames;
 			}
-			if (check_size && 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 (check_size && frames > plugin->buf_frames)
-				frames = plugin->buf_frames;
 			plugin_prev = plugin->prev;
 			if (plugin->src_frames) {
 				frames = plugin->src_frames(plugin, frames);
 				if (frames < 0)
 					return frames;
 			}
+			if (check_size && plugin->buf_frames &&
+			    frames > plugin->buf_frames)
+				frames = plugin->buf_frames;
 			plugin = plugin_prev;
 		}
 	} else