Commit 34501219 authored Jul 02, 2019 by Takashi Iwai

ALSA: line6: Fix write on zero-sized buffer



LINE6 drivers allocate the buffers based on the value returned from
usb_maxpacket() calls.  The manipulated device may return zero for
this, and this results in the kmalloc() with zero size (and it may
succeed) while the other part of the driver code writes the packet
data with the fixed size -- which eventually overwrites.

This patch adds a simple sanity check for the invalid buffer size for
avoiding that problem.

Reported-by:  <syzbot+219f00fb49874dcaea17@syzkaller.appspotmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

parent 98482377

sound/usb/line6/pcm.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -560,6 +560,11 @@ int line6_init_pcm(struct usb_line6 *line6,
		line6pcm->max_packet_size_out =
		usb_maxpacket(line6->usbdev,
		usb_sndisocpipe(line6->usbdev, ep_write), 1);
		if (!line6pcm->max_packet_size_in \|\| !line6pcm->max_packet_size_out) {
		dev_err(line6pcm->line6->ifcdev,
		"cannot get proper max packet size\n");
		return -EINVAL;
		}

		spin_lock_init(&line6pcm->out.lock);
		spin_lock_init(&line6pcm->in.lock);

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