USB: fix out-of-bounds in usb_set_configuration (bd7a3fe7) · Commits · 戴 / test

Andrey Konovalov reported a possible out-of-bounds problem for a USB interface association descriptor. He writes: It seems there's no proper size check of a USB_DT_INTERFACE_ASSOCIATION descriptor. It's only checked that the size is >= 2 in usb_parse_configuration(), so find_iad() might do out-of-bounds access to intf_assoc->bInterfaceCount. And he's right, we don't check for crazy descriptors of this type very well, so resolve this problem. Yet another issue found by syzkaller... Reported-by:

Andrey Konovalov <andreyknvl@google.com> Tested-by:

Andrey Konovalov <andreyknvl@google.com> Cc: stable <stable@vger.kernel.org> Signed-off-by:

Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/config.c

+11 −3

Original line number	Diff line number	Diff line
		@@ -643,15 +643,23 @@ static int usb_parse_configuration(struct usb_device *dev, int cfgidx,

		} else if (header->bDescriptorType ==
		USB_DT_INTERFACE_ASSOCIATION) {
		struct usb_interface_assoc_descriptor *d;

		d = (struct usb_interface_assoc_descriptor *)header;
		if (d->bLength < USB_DT_INTERFACE_ASSOCIATION_SIZE) {
		dev_warn(ddev,
		"config %d has an invalid interface association descriptor of length %d, skipping\n",
		cfgno, d->bLength);
		continue;
		}

		if (iad_num == USB_MAXIADS) {
		dev_warn(ddev, "found more Interface "
		"Association Descriptors "
		"than allocated for in "
		"configuration %d\n", cfgno);
		} else {
		config->intf_assoc[iad_num] =
		(struct usb_interface_assoc_descriptor
		*)header;
		config->intf_assoc[iad_num] = d;
		iad_num++;
		}

include/uapi/linux/usb/ch9.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -780,6 +780,7 @@ struct usb_interface_assoc_descriptor {
		__u8 iFunction;
		} __attribute__ ((packed));

		#define USB_DT_INTERFACE_ASSOCIATION_SIZE 8

		/-------------------------------------------------------------------------/

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