diff options
| author | Alan Stern <stern@rowland.harvard.edu> | 2017-12-12 14:25:13 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-12-20 10:04:51 +0100 |
| commit | dfdf5fa3e6647c0fc02be8d857b6b8b7098946ff (patch) | |
| tree | 7648b8ebbf28d5ac70bfba4b5ff064b3e0e4dc78 /drivers | |
| parent | 05de6fa5c0e2fbbed4d41eaf2b474a863c544532 (diff) | |
USB: core: prevent malicious bNumInterfaces overflow
commit 48a4ff1c7bb5a32d2e396b03132d20d552c0eca7 upstream.
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -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 b1ece1f618c8..f6fde903fcad 100644 --- a/drivers/usb/core/config.c +++ b/drivers/usb/core/config.c @@ -521,6 +521,9 @@ 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) { @@ -534,7 +537,6 @@ 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", |