USB: validate wMaxPacketValue entries in endpoint descriptors

USB: validate wMaxPacketValue entries in endpoint descriptors

Erroneous or malicious endpoint descriptors may have non-zero bits in
reserved positions, or out-of-bounds values.  This patch helps prevent
these from causing problems by bounds-checking the wMaxPacketValue
entries in endpoint descriptors and capping the values at the maximum
allowed.

This issue was first discovered and tests were conducted by Jake Lamberson
<[email protected]>, an intern working for Rosie Hall.

Signed-off-by: Alan Stern <[email protected]>
Reported-by: roswest <[email protected]>
Tested-by: roswest <[email protected]>
CC: <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>