[PATCH v2 4/5] liveupdate: validate restored LUO file set metadata

[Cris Jacob Maamor <crisjacobmaamor@gmail.com>]

The restored session metadata provides the LUO file set address and count.
LUO maps that address with phys_to_virt() and uses the restored count to
walk the serialized file array.

Reject invalid empty file set metadata, reject counts above LUO_FILE_MAX,
and check that the physical range is KHO-preserved before mapping it.

Signed-off-by: Cris Jacob Maamor <crisjacobmaamor@gmail.com>
---
 kernel/liveupdate/luo_file.c | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/kernel/liveupdate/luo_file.c b/kernel/liveupdate/luo_file.c
index a0a419085e28..cde43d822f8f 100644
--- a/kernel/liveupdate/luo_file.c
+++ b/kernel/liveupdate/luo_file.c
@@ -783,11 +783,21 @@ int luo_file_deserialize(struct luo_file_set *file_set,
 	struct luo_file_ser *file_ser;
 	u64 i;
 
-	if (!file_set_ser->files) {
-		WARN_ON(file_set_ser->count);
+	if (!file_set_ser->count) {
+		if (file_set_ser->files)
+			return -EINVAL;
 		return 0;
 	}
 
+	if (file_set_ser->count > LUO_FILE_MAX)
+		return -EINVAL;
+
+	if (!file_set_ser->files)
+		return -EINVAL;
+
+	if (!kho_is_preserved(file_set_ser->files, LUO_FILE_PGCNT))
+		return -EINVAL;
+
 	file_set->count = file_set_ser->count;
 	file_set->files = phys_to_virt(file_set_ser->files);
 
-- 
2.53.0