[PATCH] Squashfs: fix xattr id and id lookup sanity checks

[Phillip Lougher]

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

Cc: sta...@vger.kernel.org
Signed-off-by: Phillip Lougher <phil...@squashfs.org.uk>
---
 fs/squashfs/id.c       | 6 ++++--
 fs/squashfs/xattr_id.c | 6 ++++--
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/fs/squashfs/id.c b/fs/squashfs/id.c
index 11581bf31af4..ea5387679723 100644
--- a/fs/squashfs/id.c
+++ b/fs/squashfs/id.c
@@ -97,14 +97,16 @@ __le64 *squashfs_read_id_index_table(struct super_block *sb,
                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);
        }
diff --git a/fs/squashfs/xattr_id.c b/fs/squashfs/xattr_id.c
index ead66670b41a..087cab8c78f4 100644
--- a/fs/squashfs/xattr_id.c
+++ b/fs/squashfs/xattr_id.c
@@ -109,14 +109,16 @@ __le64 *squashfs_read_xattr_id_table(struct super_block 
*sb, u64 table_start,
                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);
        }
-- 
2.29.2