This is a note to let you know that I've just added the patch titled
USB: core: prevent malicious bNumInterfaces overflow
to my usb git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
in the usb-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 48a4ff1c7bb5a32d2e396b03132d20d552c0eca7 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Date: Tue, 12 Dec 2017 14:25:13 -0500
Subject: USB: core: prevent malicious bNumInterfaces overflow
A malicious USB device with crafted descriptors can cause the kernel
to access unallocated memory by setting the bNumInterfaces value too
high in a configuration descriptor. Although the value is adjusted
during parsing, this adjustment is skipped in one of the error return
paths.
This patch prevents the problem by setting bNumInterfaces to 0
initially. The existing code already sets it to the proper value
after parsing is complete.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
CC: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/core/config.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
index 55b198ba629b..78e92d29f8d9 100644
--- a/drivers/usb/core/config.c
+++ b/drivers/usb/core/config.c
@@ -555,6 +555,9 @@ static int usb_parse_configuration(struct usb_device *dev, int cfgidx,
unsigned iad_num = 0;
memcpy(&config->desc, buffer, USB_DT_CONFIG_SIZE);
+ nintf = nintf_orig = config->desc.bNumInterfaces;
+ config->desc.bNumInterfaces = 0; // Adjusted later
+
if (config->desc.bDescriptorType != USB_DT_CONFIG ||
config->desc.bLength < USB_DT_CONFIG_SIZE ||
config->desc.bLength > size) {
@@ -568,7 +571,6 @@ static int usb_parse_configuration(struct usb_device *dev, int cfgidx,
buffer += config->desc.bLength;
size -= config->desc.bLength;
- nintf = nintf_orig = config->desc.bNumInterfaces;
if (nintf > USB_MAXINTERFACES) {
dev_warn(ddev, "config %d has too many interfaces: %d, "
"using maximum allowed: %d\n",
--
2.15.1