apparmor: return -ENOMEM in unpack_perms_table upon alloc failure

[ Upstream commit 74b7105 ]

In policy_unpack.c:unpack_perms_table, the perms struct is allocated via
kcalloc, with the position being reset if the allocation fails. However,
the error path results in -EPROTO being retured instead of -ENOMEM. Fix
this to return the correct error code.

Reported-by: Zygmunt Krynicki <zygmunt.krynicki@canonical.com>
Fixes: fd1b2b9 ("apparmor: add the ability for policy to specify a permission table")
Reviewed-by: Tyler Hicks <code@tyhicks.com>
Signed-off-by: Ryan Lee <ryan.lee@canonical.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: rlee287

security/apparmor/policy_unpack.c

@@ -683,8 +683,10 @@ static ssize_t unpack_perms_table(struct aa_ext *e, struct aa_perms **perms)
 		if (!aa_unpack_array(e, NULL, &size))
 			goto fail_reset;
 		*perms = kcalloc(size, sizeof(struct aa_perms), GFP_KERNEL);
-		if (!*perms)
-			goto fail_reset;
+		if (!*perms) {
+			e->pos = pos;
+			return -ENOMEM;
+		}
 		for (i = 0; i < size; i++) {
 			if (!unpack_perm(e, version, &(*perms)[i]))
 				goto fail;