[PATCH] [248/275] sound/oss/opl3: validate voice and channel indexes

[Andi Kleen]

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>

commit 4d00135a680727f6c3be78f8befaac009030e4df upstream.

User-controllable indexes for voice and channel values may cause reading
and writing beyond the bounds of their respective arrays, leading to
potentially exploitable memory corruption.  Validate these indexes.

Signed-off-by: Dan Rosenberg <drosenberg@xxxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>

---
 sound/oss/opl3.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

Index: linux-2.6.35.y/sound/oss/opl3.c
===================================================================
--- linux-2.6.35.y.orig/sound/oss/opl3.c	2011-03-29 22:50:12.724932820 -0700
+++ linux-2.6.35.y/sound/oss/opl3.c	2011-03-29 23:03:03.451211863 -0700
@@ -849,6 +849,10 @@
 
 static void opl3_panning(int dev, int voice, int value)
 {
+
+	if (voice < 0 || voice >= devc->nr_voice)
+		return;
+
 	devc->voc[voice].panning = value;
 }
 
@@ -1066,8 +1070,15 @@
 
 static void opl3_setup_voice(int dev, int voice, int chn)
 {
-	struct channel_info *info =
-	&synth_devs[dev]->chn_info[chn];
+	struct channel_info *info;
+
+	if (voice < 0 || voice >= devc->nr_voice)
+		return;
+
+	if (chn < 0 || chn > 15)
+		return;
+
+	info = &synth_devs[dev]->chn_info[chn];
 
 	opl3_set_instr(dev, voice, info->pgm_num);
 
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