[PATCH 1/4] fs/hfsplus: Validate btree node size

[Lidong Chen]

The invalid btree node size can cause crashes when parsing
the btree. The fix is to ensure the btree node size is within
the valid range defined in the HFS Plus techical note, TN1150.

https://developer.apple.com/library/archive/technotes/tn/tn1150.html

Signed-off-by: Lidong Chen <lidong.chen@oracle.com>
---
 grub-core/fs/hfsplus.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/grub-core/fs/hfsplus.c b/grub-core/fs/hfsplus.c
index 6337cbfcb..1ffebc8be 100644
--- a/grub-core/fs/hfsplus.c
+++ b/grub-core/fs/hfsplus.c
@@ -84,6 +84,9 @@ struct grub_hfsplus_catfile
 #define GRUB_HFSPLUS_FILEMODE_DIRECTORY        0040000
 #define GRUB_HFSPLUS_FILEMODE_SYMLINK  0120000
 
+#define HFSPLUS_BTNODE_MINSZ   (1 << 9)
+#define HFSPLUS_BTNODE_MAXSZ   (1 << 15)
+
 /* Some pre-defined file IDs.  */
 enum
   {
@@ -584,6 +587,10 @@ grub_hfsplus_btree_search (struct grub_hfsplus_btree 
*btree,
       return 0;
     }
 
+  if (btree->nodesize < HFSPLUS_BTNODE_MINSZ ||
+      btree->nodesize > HFSPLUS_BTNODE_MAXSZ)
+    return grub_error (GRUB_ERR_BAD_FS, "invalid HFS+ btree node size");
+
   node = grub_malloc (btree->nodesize);
   if (! node)
     return grub_errno;
-- 
2.39.1