Commit 85c50a58 authored by Dan Carpenter's avatar Dan Carpenter Committed by Takashi Iwai

ALSA: seq: seq_oss_event: missing range checks

The "dev" variable could be out of bounds.  Calling
snd_seq_oss_synth_is_valid() checks that it is is a valid device
which has been opened.  We check this inside set_note_event() so
this function can't succeed without a valid "dev".  But we need to
do the check earlier to prevent invalid dereferences and memory
corruption.

One call tree where "dev" could be out of bounds is:
-> snd_seq_oss_oob_user()
   -> snd_seq_oss_process_event()
      -> extended_event()
         -> note_on_event()
Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent 6dbe51c2
...@@ -285,7 +285,12 @@ local_event(struct seq_oss_devinfo *dp, union evrec *q, struct snd_seq_event *ev ...@@ -285,7 +285,12 @@ local_event(struct seq_oss_devinfo *dp, union evrec *q, struct snd_seq_event *ev
static int static int
note_on_event(struct seq_oss_devinfo *dp, int dev, int ch, int note, int vel, struct snd_seq_event *ev) note_on_event(struct seq_oss_devinfo *dp, int dev, int ch, int note, int vel, struct snd_seq_event *ev)
{ {
struct seq_oss_synthinfo *info = &dp->synths[dev]; struct seq_oss_synthinfo *info;
if (!snd_seq_oss_synth_is_valid(dp, dev))
return -ENXIO;
info = &dp->synths[dev];
switch (info->arg.event_passing) { switch (info->arg.event_passing) {
case SNDRV_SEQ_OSS_PROCESS_EVENTS: case SNDRV_SEQ_OSS_PROCESS_EVENTS:
if (! info->ch || ch < 0 || ch >= info->nr_voices) { if (! info->ch || ch < 0 || ch >= info->nr_voices) {
...@@ -340,7 +345,12 @@ note_on_event(struct seq_oss_devinfo *dp, int dev, int ch, int note, int vel, st ...@@ -340,7 +345,12 @@ note_on_event(struct seq_oss_devinfo *dp, int dev, int ch, int note, int vel, st
static int static int
note_off_event(struct seq_oss_devinfo *dp, int dev, int ch, int note, int vel, struct snd_seq_event *ev) note_off_event(struct seq_oss_devinfo *dp, int dev, int ch, int note, int vel, struct snd_seq_event *ev)
{ {
struct seq_oss_synthinfo *info = &dp->synths[dev]; struct seq_oss_synthinfo *info;
if (!snd_seq_oss_synth_is_valid(dp, dev))
return -ENXIO;
info = &dp->synths[dev];
switch (info->arg.event_passing) { switch (info->arg.event_passing) {
case SNDRV_SEQ_OSS_PROCESS_EVENTS: case SNDRV_SEQ_OSS_PROCESS_EVENTS:
if (! info->ch || ch < 0 || ch >= info->nr_voices) { if (! info->ch || ch < 0 || ch >= info->nr_voices) {
......
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