[PATCH 4.14 091/114] ALSA: rawmidi: Initialize allocated buffers

From: Greg Kroah-Hartman
Date: Mon May 18 2020 - 13:49:17 EST


From: Takashi Iwai <tiwai@xxxxxxx>

commit 5a7b44a8df822e0667fc76ed7130252523993bda upstream.

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@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
sound/core/rawmidi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -125,7 +125,7 @@ static int snd_rawmidi_runtime_create(st
runtime->avail = 0;
else
runtime->avail = runtime->buffer_size;
- if ((runtime->buffer = kmalloc(runtime->buffer_size, GFP_KERNEL)) == NULL) {
+ if ((runtime->buffer = kzalloc(runtime->buffer_size, GFP_KERNEL)) == NULL) {
kfree(runtime);
return -ENOMEM;
}
@@ -650,7 +650,7 @@ int snd_rawmidi_output_params(struct snd
return -EINVAL;
}
if (params->buffer_size != runtime->buffer_size) {
- newbuf = kmalloc(params->buffer_size, GFP_KERNEL);
+ newbuf = kzalloc(params->buffer_size, GFP_KERNEL);
if (!newbuf)
return -ENOMEM;
spin_lock_irq(&runtime->lock);