curl: krb5: double-free in read_data() after realloc() fail

Summary: In 'lib/security.c', there is a double-free of the reference 'buf-data' on the teardown path if 'Curlsaferealloc' fails. Also, since we read 'len' from the 'fd', the sender might be able to remotely trigger a realloc failure, and then the double-free, by sending the value 0x7fffffff...

DEBIAN-CVE-2013-4371

Use-after-free vulnerability in the libxllistcpupool function in the libxl toolstack library in Xen 4.2.x and 4.3.x, when running "under memory pressure," returns the original pointer when the realloc function fails, which allows local users to cause a denial of service heap corruption and crash...