From: Takashi Iwai tiwai@suse.de
commit ae769d3556644888c964635179ef192995f40793 upstream.
The recent fix for the OOB access in PCM OSS plugins (commit f2ecf903ef06: "ALSA: pcm: oss: Avoid plugin buffer overflow") caused a regression on OSS applications. The patch introduced the size check in client and slave size calculations to limit to each plugin's buffer size, but I overlooked that some code paths call those without allocating the buffer but just for estimation.
This patch fixes the bug by skipping the size check for those code paths while keeping checking in the actual transfer calls.
Fixes: f2ecf903ef06 ("ALSA: pcm: oss: Avoid plugin buffer overflow") Tested-and-reported-by: Jari Ruusu jari.ruusu@gmail.com Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20200403072515.25539-1-tiwai@suse.de Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- sound/core/oss/pcm_plugin.c | 32 ++++++++++++++++++++++++-------- 1 file changed, 24 insertions(+), 8 deletions(-)
--- a/sound/core/oss/pcm_plugin.c +++ b/sound/core/oss/pcm_plugin.c @@ -196,7 +196,9 @@ int snd_pcm_plugin_free(struct snd_pcm_p return 0; }
-snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t drv_frames) +static snd_pcm_sframes_t plug_client_size(struct snd_pcm_substream *plug, + snd_pcm_uframes_t drv_frames, + bool check_size) { struct snd_pcm_plugin *plugin, *plugin_prev, *plugin_next; int stream; @@ -209,7 +211,7 @@ snd_pcm_sframes_t snd_pcm_plug_client_si if (stream == SNDRV_PCM_STREAM_PLAYBACK) { plugin = snd_pcm_plug_last(plug); while (plugin && drv_frames > 0) { - if (drv_frames > plugin->buf_frames) + if (check_size && drv_frames > plugin->buf_frames) drv_frames = plugin->buf_frames; plugin_prev = plugin->prev; if (plugin->src_frames) @@ -222,7 +224,7 @@ snd_pcm_sframes_t snd_pcm_plug_client_si plugin_next = plugin->next; if (plugin->dst_frames) drv_frames = plugin->dst_frames(plugin, drv_frames); - if (drv_frames > plugin->buf_frames) + if (check_size && drv_frames > plugin->buf_frames) drv_frames = plugin->buf_frames; plugin = plugin_next; } @@ -231,7 +233,9 @@ snd_pcm_sframes_t snd_pcm_plug_client_si return drv_frames; }
-snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *plug, snd_pcm_uframes_t clt_frames) +static snd_pcm_sframes_t plug_slave_size(struct snd_pcm_substream *plug, + snd_pcm_uframes_t clt_frames, + bool check_size) { struct snd_pcm_plugin *plugin, *plugin_prev, *plugin_next; snd_pcm_sframes_t frames; @@ -252,14 +256,14 @@ snd_pcm_sframes_t snd_pcm_plug_slave_siz if (frames < 0) return frames; } - if (frames > plugin->buf_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 (frames > plugin->buf_frames) + if (check_size && frames > plugin->buf_frames) frames = plugin->buf_frames; plugin_prev = plugin->prev; if (plugin->src_frames) { @@ -274,6 +278,18 @@ snd_pcm_sframes_t snd_pcm_plug_slave_siz return frames; }
+snd_pcm_sframes_t snd_pcm_plug_client_size(struct snd_pcm_substream *plug, + snd_pcm_uframes_t drv_frames) +{ + return plug_client_size(plug, drv_frames, false); +} + +snd_pcm_sframes_t snd_pcm_plug_slave_size(struct snd_pcm_substream *plug, + snd_pcm_uframes_t clt_frames) +{ + return plug_slave_size(plug, clt_frames, false); +} + static int snd_pcm_plug_formats(struct snd_mask *mask, snd_pcm_format_t format) { struct snd_mask formats = *mask; @@ -628,7 +644,7 @@ snd_pcm_sframes_t snd_pcm_plug_write_tra src_channels = dst_channels; plugin = next; } - return snd_pcm_plug_client_size(plug, frames); + return plug_client_size(plug, frames, true); }
snd_pcm_sframes_t snd_pcm_plug_read_transfer(struct snd_pcm_substream *plug, struct snd_pcm_plugin_channel *dst_channels_final, snd_pcm_uframes_t size) @@ -638,7 +654,7 @@ snd_pcm_sframes_t snd_pcm_plug_read_tran snd_pcm_sframes_t frames = size; int err;
- frames = snd_pcm_plug_slave_size(plug, frames); + frames = plug_slave_size(plug, frames, true); if (frames < 0) return frames;