hfsplus: hfs_bnode_find() can fail, resulting in hfs_bnode_split() breakage

oops and fs corruption; the latter can happen even on valid fs in case of oom.

[hch: port of commit 3d10a15d6919488204bdb264050d156ced20d9aa from hfs]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@tuxera.com>

1 files changed, 15 insertions, 3 deletions

diff --git a/fs/hfsplus/brec.c b/fs/hfsplus/brec.c
index c88e5d72a402..fa903641992f 100644
--- a/fs/hfsplus/brec.c
+++ b/fs/hfsplus/brec.c
@@ -216,7 +216,7 @@ skip:
 static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd)
 {
         struct hfs_btree *tree;
-        struct hfs_bnode *node, *new_node;
+        struct hfs_bnode *node, *new_node, *next_node;
         struct hfs_bnode_desc node_desc;
         int num_recs, new_rec_off, new_off, old_rec_off;
         int data_start, data_end, size;
@@ -235,6 +235,17 @@ static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd)
         new_node->type = node->type;
         new_node->height = node->height;
 
+        if (node->next)
+                next_node = hfs_bnode_find(tree, node->next);
+        else
+                next_node = NULL;
+
+        if (IS_ERR(next_node)) {
+                hfs_bnode_put(node);
+                hfs_bnode_put(new_node);
+                return next_node;
+        }
+
         size = tree->node_size / 2 - node->num_recs * 2 - 14;
         old_rec_off = tree->node_size - 4;
         num_recs = 1;
@@ -248,6 +259,8 @@ static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd)
                 /* panic? */
                 hfs_bnode_put(node);
                 hfs_bnode_put(new_node);
+                if (next_node)
+                        hfs_bnode_put(next_node);
                 return ERR_PTR(-ENOSPC);
         }
 
@@ -302,8 +315,7 @@ static struct hfs_bnode *hfs_bnode_split(struct hfs_find_data *fd)
         hfs_bnode_write(node, &node_desc, 0, sizeof(node_desc));
 
         /* update next bnode header */
-        if (new_node->next) {
-                struct hfs_bnode *next_node = hfs_bnode_find(tree, new_node->next);
+        if (next_node) {
                 next_node->prev = new_node->this;
                 hfs_bnode_read(next_node, &node_desc, 0, sizeof(node_desc));
                 node_desc.prev = cpu_to_be32(next_node->prev);