[PATCH 1/3] posix: Remove dynamic memory allocation from execl{e,p}

[Paul Eggert]

Adhemerval Zanella wrote:
> +  int argc;
> +  va_list ap;
> +  va_start (ap, arg);
> +  for (argc = 1; va_arg (ap, const char *); argc++)
> +    continue;

With my "no arbitrary limits" hat on, I noticed that this has undefined behavior 
if more than INT_MAX arguments are passed to execl. The existing code is no 
saint in this area (it messes up badly if more than UINT_MAX args are passed), 
but the new code should not make things worse, and we might as well fix the 
UINT_MAX bug while we're at it.

Attached please find a contrived test case illustrating the bug on x86-64. This 
test succeeds on x86-64 now (in that the program prints "execl: Cannot allocate 
memory" and exits with status 0) but could crash with the proposed patch. 
Perhaps you can add this to the glibc test cases while you're at it.

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