Enable -fstack-protector for EFI builds, where binary size is less
critical than for BIOS builds.
The stack cookie must be constructed immediately on entry, which
prohibits the use of any viable entropy source. Construct a cookie by
XORing together various mildly random quantities to produce a value
that will at least not be identical on each run.
On detecting a stack corruption, attempt to call Exit() with an
appropriate error. If that fails, then lock up the machine since
there is no other safe action that can be taken.
The old conditional check for support of -fno-stack-protector is
omitted since this flag dates back to GCC 4.1.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
On a Dell OptiPlex 7010, calling DisconnectController() on the LOM
device handle will lock up the system. Debugging shows that execution
is trapped in an infinite loop that is somehow trying to reconnect
drivers (without going via ConnectController()).
The problem can be reproduced in the UEFI shell with no iPXE code
present, by using the "disconnect" command. Experimentation shows
that the only fix is to unload (rather than just disconnect) the
"Ip4ConfigDxe" driver.
Add the concept of a blacklist of UEFI drivers that will be
automatically unloaded when iPXE runs as an application, and add the
Dell Ip4ConfigDxe driver to this blacklist.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
