[PATCH] common: Fix memory leak and incorrect comparison

[Maks Mishin]

Changing the order of actions: the input argument is checked before 
memory is allocated. 

The input argument `n` is of type `size_t` and cannot take 
negative values, so the comparison has been fixed.

Signed-off-by: Maks Mishin <maks.mishinFZ at gmail.com>
---
 common/dlmalloc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/common/dlmalloc.c b/common/dlmalloc.c
index cc4d3a0a02..2f4cabda4a 100644
--- a/common/dlmalloc.c
+++ b/common/dlmalloc.c
@@ -2093,6 +2093,8 @@ Void_t* cALLOc_impl(n, elem_size) size_t n; size_t elem_size;
   mchunkptr p;
   INTERNAL_SIZE_T csz;
 
+  if ((long)n <= 0) return NULL;
+
   INTERNAL_SIZE_T sz = n * elem_size;
 
   /* check if expand_top called, in which case don't need to clear */
@@ -2104,8 +2106,6 @@ Void_t* cALLOc_impl(n, elem_size) size_t n; size_t elem_size;
 #endif
   Void_t* mem = mALLOc_impl (sz);
 
-  if ((long)n < 0) return NULL;
-
   if (mem == NULL)
     return NULL;
   else
-- 
2.34.1