[Etherboot-developers] (unsigned) char bugs

[Michael B. <mb...@fe...>]

I've noticed some strange things happening when DHCP options get longer
than 128 characters (which is easily possible if you use the
extensions-path mechanism to load an external options file via TFTP).
I've tracked it down to the lack of "unsigned" when defining character
types in places like:

char *motd[RFC1533_VENDOR_NUMOFMOTD];

which causes problems in bootmenu.c, at the point

int  i,j,k = 0;
for (i = 0; i < RFC1533_VENDOR_NUMOFMOTD; i++) if (motd[i]) {
  for (j = TAG_LEN(motd[i])

since if the DHCP option length is >=128, j will either be set to the
correct length or (correct length-256), at the discretion of the compiler.

Explicitly specifying "unsigned char" fixes the problem.  I've fixed the
ones I've come across, but it seems to be common problem in many locations
- it might be worth eliminating them all with a quick code review at some
point.

Michael Brown
http://www.fensystems.co.uk