Commit a03ff544 authored May 13, 2019 by Alan Stern Committed by Greg Kroah-Hartman May 21, 2019

USB: Fix slab-out-of-bounds write in usb_get_bos_descriptor

The syzkaller USB fuzzer found a slab-out-of-bounds write bug in the
USB core, caused by a failure to check the actual size of a BOS
descriptor. This patch adds a check to make sure the descriptor is at
least as large as it is supposed to be, so that the code doesn't
inadvertently access memory beyond the end of the allocated region
when assigning to dev->bos->desc->bNumDeviceCaps later on.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Reported-and-tested-by: <syzbot+71f1e64501a309fcc012@syzkaller.appspotmail.com>
CC: <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent a188339c

drivers/usb/core/config.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -932,8 +932,8 @@ int usb_get_bos_descriptor(struct usb_device *dev)

		/* Get BOS descriptor */
		ret = usb_get_descriptor(dev, USB_DT_BOS, 0, bos, USB_DT_BOS_SIZE);
		if (ret < USB_DT_BOS_SIZE) {
		dev_err(ddev, "unable to get BOS descriptor\n");
		if (ret < USB_DT_BOS_SIZE \|\| bos->bLength < USB_DT_BOS_SIZE) {
		dev_err(ddev, "unable to get BOS descriptor or descriptor too short\n");
		if (ret >= 0)
		ret = -ENOMSG;
		kfree(bos);

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