selinux: fix memleak in security_read_state_kernel()

selinux: fix memleak in security_read_state_kernel()

BugLink: https://bugs.launchpad.net/bugs/1990162
[ Upstream commit 73de1befcc53a7c68b0c5e76b9b5ac41c517760f ]

In this function, it directly returns the result of __security_read_policy
without freeing the allocated memory in *data, cause memory leak issue,
so free the memory if __security_read_policy failed.

Signed-off-by: Xiu Jianfeng <xiujianfeng@huawei.com>
[PM: subject line tweak]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>