C application memory consumption grows endlessly if the same DB conection has been used for a long time

In a MariaDB client memory allocation routine:

gptr alloc_root(MEM_ROOT *mem_root, size_t Size)
...
get_size= MAX(Size+ALIGN_SIZE(sizeof(USED_MEM)),
(mem_root->block_size & ~1) * (mem_root->block_num >> 2));

The problem is that if DB connection is open for a long time e.g. weeks, block_num incremented with every alloc_root call an gets quite high and get_size becomes bigger and bigger reaching finally 4GB for 32bit processes causing MariaDB application shutdown.

Workarounded it by changing alloc_root code to:

get_size= MAX(Size+ALIGN_SIZE(sizeof(MA_USED_MEM)),
(mem_root->block_size & ~1) * 1024 );

Looks working but not sure whether it is a correct solution.