linux-kernel - [PATCH 4.4 74/86] ALSA: rawmidi: Initialize allocated buffers

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Date:   Mon, 18 May 2020 19:36:45 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+194dffdb8b22fc5d207a@...kaller.appspotmail.com,
        Takashi Iwai <tiwai@...e.de>
Subject: [PATCH 4.4 74/86] ALSA: rawmidi: Initialize allocated buffers

From: Takashi Iwai <tiwai@...e.de>

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@...kaller.appspotmail.com
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/sound/core/rawmidi.c
+++ b/sound/core/rawmidi.c
@@ -136,7 +136,7 @@ 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;
 	}
@@ -661,7 +661,7 @@ 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);