LSM: remove the task field from common_audit_data

There are no legitimate users.  Always use current and get back some stack
space for the common_audit_data.
Signed-off-by: Eric Paris <eparis@redhat.com>

include/linux/lsm_audit.h

@@ -53,7 +53,6 @@ struct common_audit_data {
 #define LSM_AUDIT_DATA_KMOD	8
 #define LSM_AUDIT_DATA_INODE	9
 #define LSM_AUDIT_DATA_DENTRY	10
-	struct task_struct *tsk;
 	union 	{
 		struct path path;
 		struct dentry *dentry;

security/lsm_audit.c

@@ -213,12 +213,8 @@ static void dump_common_audit_data(struct audit_buffer *ab,
 {
 	struct task_struct *tsk = current;
 
-	if (a->tsk)
-		tsk = a->tsk;
-	if (tsk && tsk->pid) {
 	audit_log_format(ab, " pid=%d comm=", tsk->pid);
 	audit_log_untrustedstring(ab, tsk->comm);
-	}
 
 	switch (a->type) {
 	case LSM_AUDIT_DATA_NONE:

security/selinux/hooks.c

@@ -1429,7 +1429,6 @@ static int cred_has_capability(const struct cred *cred,
 
 	COMMON_AUDIT_DATA_INIT(&ad, LSM_AUDIT_DATA_CAP);
 	ad.selinux_audit_data = &sad;
-	ad.tsk = current;
 	ad.u.cap = cap;
 
 	switch (CAP_TO_INDEX(cap)) {