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

[Adhemerval Zanella]

On 25-02-2016 04:27, Paul Eggert wrote:
> 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.
> 

AFAIK the C standard defines the main entrypoint argc as signed int, so 
I think it is indeed undefined behaviour if you intend to call a program
with more than INT_MAX arguments.


> 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.
>