sound: sequencer: cap array index in seq_chn_common_event()

"chn" here is a number between 0 and 255, but ->chn_info[] only has
16 elements so there is a potential write beyond the end of the
array.

If the seq_mode isn't SEQ_2 then we let the individual drivers
(either opl3.c or midi_synth.c) handle it.  Those functions all
do a bounds check on "chn" so I haven't changed anything here.
The opl3.c driver has up to 18 channels and not 16.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 6 insertions, 0 deletions

diff --git a/sound/oss/sequencer.c b/sound/oss/sequencer.c
index 30bcfe470f83..4ff60a6427d9 100644
--- a/sound/oss/sequencer.c
+++ b/sound/oss/sequencer.c
@@ -545,6 +545,9 @@ static void seq_chn_common_event(unsigned char *event_rec)
                 case MIDI_PGM_CHANGE:
                         if (seq_mode == SEQ_2)
                         {
+                                if (chn > 15)
+                                        break;
+
                                 synth_devs[dev]->chn_info[chn].pgm_num = p1;
                                 if ((int) dev >= num_synths)
                                         synth_devs[dev]->set_instr(dev, chn, p1);
@@ -596,6 +599,9 @@ static void seq_chn_common_event(unsigned char *event_rec)
                 case MIDI_PITCH_BEND:
                         if (seq_mode == SEQ_2)
                         {
+                                if (chn > 15)
+                                        break;
+
                                 synth_devs[dev]->chn_info[chn].bender_value = w14;
 
                                 if ((int) dev < num_synths)