ulong is 64 bits on 64-bit platforms. Hence, simple_xtoa can
produce up to 16 hex characters + NULL byte. The initrd_filesize
buffer is only 10 bytes which can cause a buffer overflow on
every PXE boot that loads an initrd on an address greater than
4GB.
Increase buffer size to 17 bytes to hold the maximum hex
representation of a 64-bit address.
Signed-off-by: Francois Berder <fberder@outlook.fr>
Reviewed-by: Jerome Forissier <jerome.forissier@arm.com>