diff options
| author | Daniel Thompson <daniel@redfelineninja.org.uk> | 2014-12-05 11:48:59 +0300 |
|---|---|---|
| committer | Karl Palsson <karlp@tweak.net.au> | 2014-12-19 01:50:27 +0300 |
| commit | 0b63408260ad59fbfead05b94ada309d1f08e7a4 (patch) | |
| tree | aba9fb28c604dea320e26c4cca2b89ae2127ae27 /lib/usb | |
| parent | 342ec6e9e3d947d3d267e753febace913e942515 (diff) | |
usb: Prevent memcpy() being called with NULL arguments
If there is no additional iface data then iface->extra is NULL and
iface->extralen is zero. Passing NULL to memcpy is undefined behaviour
even if the length of data to copy is zero. In other words a conforming
(debug) memcpy implementation is permitted to assert(dst && src) without
checking the value of n.
Add an extra branch to avoid this.
Diffstat (limited to 'lib/usb')
| -rw-r--r-- | lib/usb/usb_standard.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/lib/usb/usb_standard.c b/lib/usb/usb_standard.c index 3b0dac9a..42458722 100644 --- a/lib/usb/usb_standard.c +++ b/lib/usb/usb_standard.c @@ -93,12 +93,14 @@ static uint16_t build_config_descriptor(usbd_device *usbd_dev, total += count; totallen += iface->bLength; /* Copy extra bytes (function descriptors). */ - memcpy(buf, iface->extra, - count = MIN(len, iface->extralen)); - buf += count; - len -= count; - total += count; - totallen += iface->extralen; + if (iface->extra) { + memcpy(buf, iface->extra, + count = MIN(len, iface->extralen)); + buf += count; + len -= count; + total += count; + totallen += iface->extralen; + } /* For each endpoint... */ for (k = 0; k < iface->bNumEndpoints; k++) { const struct usb_endpoint_descriptor *ep = |