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

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

sound/core/seq/oss/seq_oss_event.c

+12 −2
Original line number Diff line number Diff line
@@ -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) {