An integer overflow occurs, with the overflowed value used in a sensitive operation

Defect 101170 (STATIC_C)
Checker INTEGER_OVERFLOW (subcategory none)
File: /src/bson/bson-string.c
Function bson_vsnprintf
/src/bson/bson-string.c, line: 622
Subtract operation overflows on operands "size" and "1UL", whose values are unsigned constants, 0 and 1, respectively.

       str[size - 1] = '\0';

File: /src/bson/bson-string.c
Function bson_vsnprintf
/src/bson/bson-string.c, line: 622
Subtract operation overflows on operands "size" and "1UL".

       str[size - 1] = '\0';

/src/bson/bson-string.c, line: 622
Overflowed or truncated value (or a value computed from an overflowed or truncated value) "str + (size - 1UL)" dereferenced.

       str[size - 1] = '\0';