From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001

From: Daniel Axtens <dja@axtens.net>

Date: Fri, 22 Jan 2021 18:13:56 +1100

Subject: [PATCH] fs/hfsplus: Don't fetch a key beyond the end of the node

Otherwise you get a wild pointer, leading to a bunch of invalid reads.

Check it falls inside the given node.

Signed-off-by: Daniel Axtens <dja@axtens.net>

Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

---

 grub-core/fs/hfsplus.c | 4 ++++

 1 file changed, 4 insertions(+)

diff --git a/grub-core/fs/hfsplus.c b/grub-core/fs/hfsplus.c

index 03a33ea24..423f4b956 100644

--- a/grub-core/fs/hfsplus.c

+++ b/grub-core/fs/hfsplus.c

@@ -635,6 +635,10 @@ grub_hfsplus_btree_search (struct grub_hfsplus_btree *btree,

 	      pointer = ((char *) currkey

 			 + grub_be_to_cpu16 (currkey->keylen)

 			 + 2);

+

+	      if ((char *) pointer > node + btree->nodesize - 2)

+		return grub_error (GRUB_ERR_BAD_FS, "HFS+ key beyond end of node");

+

 	      currnode = grub_be_to_cpu32 (grub_get_unaligned32 (pointer));

 	      match = 1;

 	    }