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@rowland.harvard.edu 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@rowland.harvard.edu Reported-by: Andrey Konovalov andreyknvl@google.com CC: stable@vger.kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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",