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: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Takashi Iwai <tiwai@suse.de>
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@ -285,7 +285,12 @@ local_event(struct seq_oss_devinfo *dp, union evrec *q, struct snd_seq_event *ev
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static int
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note_on_event(struct seq_oss_devinfo *dp, int dev, int ch, int note, int vel, struct snd_seq_event *ev)
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{
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struct seq_oss_synthinfo *info = &dp->synths[dev];
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struct seq_oss_synthinfo *info;
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if (!snd_seq_oss_synth_is_valid(dp, dev))
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return -ENXIO;
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info = &dp->synths[dev];
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switch (info->arg.event_passing) {
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case SNDRV_SEQ_OSS_PROCESS_EVENTS:
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if (! info->ch || ch < 0 || ch >= info->nr_voices) {
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@ -340,7 +345,12 @@ note_on_event(struct seq_oss_devinfo *dp, int dev, int ch, int note, int vel, st
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static int
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note_off_event(struct seq_oss_devinfo *dp, int dev, int ch, int note, int vel, struct snd_seq_event *ev)
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{
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struct seq_oss_synthinfo *info = &dp->synths[dev];
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struct seq_oss_synthinfo *info;
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if (!snd_seq_oss_synth_is_valid(dp, dev))
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return -ENXIO;
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info = &dp->synths[dev];
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switch (info->arg.event_passing) {
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case SNDRV_SEQ_OSS_PROCESS_EVENTS:
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if (! info->ch || ch < 0 || ch >= info->nr_voices) {
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