[PATCH 4.9 19/53] squashfs: fix xattr id and id lookup sanity checks

[Greg Kroah-Hartman]

From: Phillip Lougher <phillip@xxxxxxxxxxxxxxx>

commit 8b44ca2b634527151af07447a8090a5f3a043321 upstream.

The checks for maximum metadata block size is missing
SQUASHFS_BLOCK_OFFSET (the two byte length count).

Link: https://lkml.kernel.org/r/2069685113.2081245.1614583677427@xxxxxxxxxxxxxxxxxxxxx
Fixes: f37aa4c7366e23f ("squashfs: add more sanity checks in id lookup")
Signed-off-by: Phillip Lougher <phillip@xxxxxxxxxxxxxxx>
Cc: Sean Nyekjaer <sean@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/squashfs/id.c       |    6 ++++--
 fs/squashfs/xattr_id.c |    6 ++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

--- a/fs/squashfs/id.c
+++ b/fs/squashfs/id.c
@@ -110,14 +110,16 @@ __le64 *squashfs_read_id_index_table(str
 		start = le64_to_cpu(table[n]);
 		end = le64_to_cpu(table[n + 1]);
 
-		if (start >= end || (end - start) > SQUASHFS_METADATA_SIZE) {
+		if (start >= end || (end - start) >
+				(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
 			kfree(table);
 			return ERR_PTR(-EINVAL);
 		}
 	}
 
 	start = le64_to_cpu(table[indexes - 1]);
-	if (start >= id_table_start || (id_table_start - start) > SQUASHFS_METADATA_SIZE) {
+	if (start >= id_table_start || (id_table_start - start) >
+				(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
 		kfree(table);
 		return ERR_PTR(-EINVAL);
 	}
--- a/fs/squashfs/xattr_id.c
+++ b/fs/squashfs/xattr_id.c
@@ -122,14 +122,16 @@ __le64 *squashfs_read_xattr_id_table(str
 		start = le64_to_cpu(table[n]);
 		end = le64_to_cpu(table[n + 1]);
 
-		if (start >= end || (end - start) > SQUASHFS_METADATA_SIZE) {
+		if (start >= end || (end - start) >
+				(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
 			kfree(table);
 			return ERR_PTR(-EINVAL);
 		}
 	}
 
 	start = le64_to_cpu(table[indexes - 1]);
-	if (start >= table_start || (table_start - start) > SQUASHFS_METADATA_SIZE) {
+	if (start >= table_start || (table_start - start) >
+				(SQUASHFS_METADATA_SIZE + SQUASHFS_BLOCK_OFFSET)) {
 		kfree(table);
 		return ERR_PTR(-EINVAL);
 	}