[PATCH 3/3] ubifs: check node hash calculation errors

[<shao.mingyin@zte.com.cn>]

ubifs_node_calc_hash() can fail when authentication is enabled and the
crypto operation fails.  Five calls ignore the return value and use the
uninitialized stack buffer as the node hash: replay_bud() stores it in
the replay entry, make_idx_node() and write_index() copy it into the
parent branch or the index root, and create_default_filesystem() copies
it into an index branch and into the master node.  Verifying those nodes
later then fails with a hash mismatch.

Propagate the error from all five call sites.

Fixes: 16a26b20d2af ("ubifs: authentication: Add hashes to index nodes")
Fixes: 104115a3eb54 ("ubifs: Add hashes and HMACs to default filesystem")
Cc: stable@vger.kernel.org
Signed-off-by: Shao Mingyin <shao.mingyin@zte.com.cn>
---
diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index 263045e05cf1..442493dc18c6 100644
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -730,7 +730,9 @@ static int replay_bud(struct ubifs_info *c, struct bud_entry *b)
 			goto out_dump;
 		}

-		ubifs_node_calc_hash(c, snod->node, hash);
+		err = ubifs_node_calc_hash(c, snod->node, hash);
+		if (err)
+			goto out;

 		if (snod->sqnum > c->max_sqnum)
 			c->max_sqnum = snod->sqnum;
diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index e7693b94e5b5..1c176be261e0 100644
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -329,14 +329,18 @@ static int create_default_filesystem(struct ubifs_info *c)
 	if (err)
 		goto out;

-	ubifs_node_calc_hash(c, ino, hash);
+	err = ubifs_node_calc_hash(c, ino, hash);
+	if (err)
+		goto out;
 	ubifs_copy_hash(c, hash, ubifs_branch_hash(c, br));

 	err = ubifs_write_node(c, idx, idx_node_size, main_first + DEFAULT_IDX_LEB, 0);
 	if (err)
 		goto out;

-	ubifs_node_calc_hash(c, idx, hash);
+	err = ubifs_node_calc_hash(c, idx, hash);
+	if (err)
+		goto out;
 	ubifs_copy_hash(c, hash, mst->hash_root_idx);

 	err = ubifs_write_node_hmac(c, mst, UBIFS_MST_NODE_SZ, UBIFS_MST_LNUM, 0,
diff --git a/fs/ubifs/tnc_commit.c b/fs/ubifs/tnc_commit.c
index 7bf2672062a2..1a62739c3731 100644
--- a/fs/ubifs/tnc_commit.c
+++ b/fs/ubifs/tnc_commit.c
@@ -52,7 +52,9 @@ static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
 		}
 	}
 	ubifs_prepare_node(c, idx, len, 0);
-	ubifs_node_calc_hash(c, idx, hash);
+	err = ubifs_node_calc_hash(c, idx, hash);
+	if (err)
+		return err;

 	znode->lnum = lnum;
 	znode->offs = offs;
@@ -887,7 +889,9 @@ static int write_index(struct ubifs_info *c)
 		}
 		len = ubifs_idx_node_sz(c, znode->child_cnt);
 		ubifs_prepare_node(c, idx, len, 0);
-		ubifs_node_calc_hash(c, idx, hash);
+		err = ubifs_node_calc_hash(c, idx, hash);
+		if (err)
+			return err;

 		mutex_lock(&c->tnc_mutex);