variable argument list pointers aren't traced as allocation targets resulting in false positives for PULSE_UNINITIALIZED_VALUE and MEMORY_LEAK_C

[grooverdan]

The use of a variable argument list to allocate a memory block once for its argument pointers at once isn't traced to the returning function.

x.c:

#include <stdarg.h>
#include <stdlib.h>

void *ma_multi_malloc(int myFlags, ...)
{
  va_list args;
  char **ptr,*start,*res;
  size_t tot_length,length;

  va_start(args,myFlags);
  tot_length=0;
  while (va_arg(args, char **))
  {
    length=va_arg(args, size_t);
    tot_length+=length;
  }
  va_end(args);
         
  if (!(start=(char *)malloc(tot_length)))
    return 0;
      
  va_start(args,myFlags);
  res=start;
  while ((ptr=va_arg(args, char **)))
  {
    *ptr=res;
    length=va_arg(args,size_t);
    res+=length;
  }
  va_end(args);
  return start;
}

void test()
{
  char *v, *u; 
  ma_multi_malloc(0, &v, (size_t) 1, &u, (size_t) 3);
  *v='d';
  *u='o';
  free(v);  
}

3/3 [################################################################################] 100% 52.5ms

/tmp/x.c:37: error: Memory Leak(MEMORY_LEAK_C)
  Memory dynamically allocated by `malloc`, indirectly via call to `ma_multi_malloc()` on line 37 is not freed after the last access at line 37, column 3. 
  35. {
  36.   char *v, *u;
  37.   ma_multi_malloc(0, &v, (size_t) 1, &u, (size_t) 3);
        ^
  38.   *v='d';
  39.   *u='o';

/tmp/x.c:38: error: Uninitialized Value(PULSE_UNINITIALIZED_VALUE)
  `v` is read without initialization. 
  36.   char *v, *u;
  37.   ma_multi_malloc(0, &v, (size_t) 1, &u, (size_t) 3);
  38.   *v='d';
         ^
  39.   *u='o';
  40.   free(v);  

/tmp/x.c:39: error: Uninitialized Value(PULSE_UNINITIALIZED_VALUE)
  `u` is read without initialization. 
  37.   ma_multi_malloc(0, &v, (size_t) 1, &u, (size_t) 3);
  38.   *v='d';
  39.   *u='o';
         ^
  40.   free(v);  
  41. }


Found 3 issues
                      Issue Type(ISSUED_TYPE_ID): #
  Uninitialized Value(PULSE_UNINITIALIZED_VALUE): 2
                      Memory Leak(MEMORY_LEAK_C): 1

$ infer --version
Infer version v1.2.0-49969b1487