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 --- sound/usb/line6/pcm.c | 5 +++++ 1 file changed, 5 insertions(+)

diff --git a/sound/usb/line6/pcm.c b/sound/usb/line6/pcm.c index 72c6f8e82a7e..78c2d6cab3b5 100644 --- a/sound/usb/line6/pcm.c +++ b/sound/usb/line6/pcm.c @@ -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);