ALSA: pcm: oss: Place the plugin buffer overflow checks correctly

BugLink: https://bugs.launchpad.net/bugs/1878256
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@vger.kernel.org>
Link: https://lore.kernel.org/r/20200424193350.19678-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

diff --git a/sound/core/oss/pcm_plugin.c b/sound/core/oss/pcm_plugin.c
index 3ecc070738e872f3419fef8f65ab1a0ea4f85b44..c1315ce98b54831fd0af53c711484dec916cb034 100644 (file)
--- 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_size(struct snd_pcm_substream *plug,
        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(struct snd_pcm_substream *plug,
                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