binder: use cred instead of task for getsecid

stable inclusion
from stable-v5.10.80
commit afbec52fbce006a775edb21f87ccae713bc0e7d6
category: bugfix
bugzilla: 188431, https://gitee.com/src-openeuler/kernel/issues/I6DKVG
CVE: CVE-2023-20938

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=afbec52fbce006a775edb21f87ccae713bc0e7d6



--------------------------------

commit 4d5b5539 upstream.

Use the 'struct cred' saved at binder_open() to lookup
the security ID via security_cred_getsecid(). This
ensures that the security context that opened binder
is the one used to generate the secctx.

Cc: stable@vger.kernel.org # 5.4+
Fixes: ec74136d ("binder: create node flag to request sender's security context")
Signed-off-by: Todd Kjos <tkjos@google.com>
Suggested-by: Stephen Smalley <stephen.smalley.work@gmail.com>
Reported-by: kernel test robot <lkp@intel.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
Reviewed-by: Zheng Yejian <zhengyejian1@huawei.com>
Reviewed-by: Wang Weiyang <wangweiyang2@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>