[PATCH 5.10.y] apparmor: fix refcount leak in aa_get_newest_profile()

[Sasha Levin <sashal@kernel.org>]

From: John Johansen <john.johansen@canonical.com>

[ Upstream commit 33ed50716251d5b2875706c40d0c8082d46be0b1 ]

The labels_profile() macro is evaluating its argument twice

  #define labels_profile(X) ((X)->vec[(X)->size - 1])

unfortunately aa_get_newest_profile() passes
   aa_get_newest_label(&p->label)
so every call to aa_get_newest_profile results in 2 refcounts
being taken with one being leaked.

There is no need for labels_profile() to be a macro. Convert it to
an inline fn, which ensures all uses are passing the correct struct
and removes the double evaluation.

Fixes: 637f688dc3dc ("apparmor: switch from profiles to using labels on contexts")
Cc: stable@vger.kernel.org
Reported-by: Georgia Garcia <georgia.garcia@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
[ sashal: adjusted context around labels_profile() for differences in surrounding macros and declarations ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 security/apparmor/include/label.h | 6 +++++-
 security/apparmor/label.c         | 1 -
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/security/apparmor/include/label.h b/security/apparmor/include/label.h
index a987bd117d88d..e7e0f3e0435fc 100644
--- a/security/apparmor/include/label.h
+++ b/security/apparmor/include/label.h
@@ -148,7 +148,11 @@ do {							\
 #define __label_make_stale(X) ((X)->flags |= FLAG_STALE)
 #define labels_ns(X) (vec_ns(&((X)->vec[0]), (X)->size))
 #define labels_set(X) (&labels_ns(X)->labels)
-#define labels_profile(X) ((X)->vec[(X)->size - 1])
+
+static inline struct aa_profile *labels_profile(const struct aa_label *label)
+{
+	return label->vec[label->size - 1];
+}
 
 
 int aa_label_next_confined(struct aa_label *l, int i);
diff --git a/security/apparmor/label.c b/security/apparmor/label.c
index c675a11d8a551..f14802e2c2264 100644
--- a/security/apparmor/label.c
+++ b/security/apparmor/label.c
@@ -377,7 +377,6 @@ void aa_label_kref(struct kref *kref)
 		label_free_switch(label);
 		return;
 	}
-	/* TODO: update labels_profile macro so it works here */
 	AA_BUG(label_isprofile(label) &&
 	       on_list_rcu(&label->vec[0]->base.profiles));
 	AA_BUG(label_isprofile(label) &&
-- 
2.53.0