rh#1333330 / CVE-2016-4487

A vulnerability was found in gcc. There is a variable bsize storing the amount of allocated memory for the array btypevec. bsize being zero (0) indicates that some memory must be allocated upon the first write. When more memory is needed, both bsize and the memory are doubled during reallocation. At some point the memory for the array is freed (in squangle_mop_up) but the value of bsize remains. Since bsize is not 0, there is no indication that new memory must be allocated when there is another write to the array. This results in NULL being written to the freed memory.

External references:

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70481

Upstream fix:

https://gcc.gnu.org/ml/gcc-patches/2016-03/msg01687.html

References:
https://bugzilla.redhat.com/show_bug.cgi?id=1333330
http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2016-4487
http://seclists.org/oss-sec/2016/q2/240