process-execute segfaults with huge amount of arguments

[Vasilij Schneidermann]

I've noticed this while using a script with the autocompile egg. Minimal reproduction example by sjamaan:

(process-execute "/bin/echo" (map ->string (iota 4000)))

[sjamaan]

Putting it on 4.12 for the time being, under the assumption that it's likely something simple.

[LemonBoy]

Luckily it is quite simple this time :)
[wrt posixunix.scm, the same applies for the windows variant] The setarg/setenv functions will blindly set the i-th element of the given array without checking if the index is within the array boundaries; what happens here is a silly buffer overflow of the C_exec_args/C_exec_env buffers.

PS: It's probably worth to add a NULL guard for the malloc in C_set_arg_string.

[sjamaan]

There's already a patch proposed by C-Keen, and then an improved larger-scale refactoring + patch based on that, which is awaiting review on ​chicken-hackers

[sjamaan]

Fixed in 0d20426 / adcec28