ALSA: rawmidi: Initialize allocated buffers

syzbot reported the uninitialized value exposure in certain situations
using virmidi loop.  It's likely a very small race at writing and
reading, and the influence is almost negligible.  But it's safer to
paper over this just by replacing the existing kvmalloc() with
kvzalloc().

Reported-by: syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c
index 69517e1..08d5662 100644 (file)
--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -129,7 +129,7 @@ static int snd_rawmidi_runtime_create(struct snd_rawmidi_substream *substream)
                runtime->avail = 0;
        else
                runtime->avail = runtime->buffer_size;
-       runtime->buffer = kvmalloc(runtime->buffer_size, GFP_KERNEL);
+       runtime->buffer = kvzalloc(runtime->buffer_size, GFP_KERNEL);
        if (!runtime->buffer) {
                kfree(runtime);
                return -ENOMEM;
@@ -655,7 +655,7 @@ static int resize_runtime_buffer(struct snd_rawmidi_runtime *runtime,
        if (params->avail_min < 1 || params->avail_min > params->buffer_size)
                return -EINVAL;
        if (params->buffer_size != runtime->buffer_size) {
-               newbuf = kvmalloc(params->buffer_size, GFP_KERNEL);
+               newbuf = kvzalloc(params->buffer_size, GFP_KERNEL);
                if (!newbuf)
                        return -ENOMEM;
                spin_lock_irq(&runtime->lock);