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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+194dffdb8b22fc5d207a@syzkaller.appspotmail.com,
        Takashi Iwai <tiwai@suse.de>
Subject: [PATCH 4.9 74/90] ALSA: rawmidi: Initialize allocated buffers
Date:   Mon, 18 May 2020 19:36:52 +0200
Message-Id: <20200518173506.329434545@linuxfoundation.org>
In-Reply-To: <20200518173450.930655662@linuxfoundation.org>
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From: Takashi Iwai <tiwai@suse.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@syzkaller.appspotmail.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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);