sound/oss/opl3: validate voice and channel indexes

BugLink: http://bugs.launchpad.net/bugs/761134

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@vsecurity.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

diff --git a/sound/oss/opl3.c b/sound/oss/opl3.c
index 938c48c..f4ffdff 100644 (file)
--- a/sound/oss/opl3.c
+++ b/sound/oss/opl3.c
@@ -849,6 +849,10 @@ static int opl3_load_patch(int dev, int format, const char __user *addr,
 
 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 int opl3_alloc_voice(int dev, int chn, int note, struct voice_alloc_info
 
 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);