diff options
| author | Alan Stern | 2017-12-12 14:25:13 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2017-12-13 12:28:43 +0100 |
| commit | 48a4ff1c7bb5a32d2e396b03132d20d552c0eca7 (patch) | |
| tree | 4cb8b7afc26ba9e3ad44425f393baa08715c4852 /drivers/usb | |
| parent | cf4df407e0d7cde60a45369c2a3414d18e2d4fdd (diff) | |
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>
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | drivers/usb/core/config.c | 4 |
1 files changed, 3 insertions, 1 deletions
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", |