3.16.50-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> commit 1c0edc3633b56000e18d82fc241e3995ca18a69e upstream. Andrey used the syzkaller fuzzer to find an out-of-bounds memory access in usb_get_bos_descriptor(). The code wasn't checking that the next usb_dev_cap_header structure could fit into the remaining buffer space. This patch fixes the error and also reduces the bNumDeviceCaps field in the header to match the actual number of capabilities found, in cases where there are fewer than expected. Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx> --- drivers/usb/core/config.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/usb/core/config.c +++ b/drivers/usb/core/config.c @@ -924,10 +924,12 @@ int usb_get_bos_descriptor(struct usb_de for (i = 0; i < num; i++) { buffer += length; cap = (struct usb_dev_cap_header *)buffer; - length = cap->bLength; - if (total_len < length) + if (total_len < sizeof(*cap) || total_len < cap->bLength) { + dev->bos->desc->bNumDeviceCaps = i; break; + } + length = cap->bLength; total_len -= length; if (cap->bDescriptorType != USB_DT_DEVICE_CAPABILITY) {