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ALSA: seq: seq_oss_event: missing range checks

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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: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Dan Carpenter 2013-03-04 15:19:18 +03:00 committed by Takashi Iwai
parent 6dbe51c251
commit 85c50a5899
1 changed files with 12 additions and 2 deletions
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14
sound/core/seq/oss/seq_oss_event.c
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@ -285,7 +285,12 @@ local_event(struct seq_oss_devinfo *dp, union evrec *q, struct snd_seq_event *ev
static int
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) {
case SNDRV_SEQ_OSS_PROCESS_EVENTS:
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
static int
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) {
case SNDRV_SEQ_OSS_PROCESS_EVENTS:
if (! info->ch || ch < 0 || ch >= info->nr_voices) {