nilfs2: verify metadata sizes read from disk

Add code to check sizes of on-disk data of metadata files such as inode
size, segment usage size, DAT entry size, and checkpoint size.  Although
these sizes are read from disk, the current implementation doesn't check
them.

If these sizes are not sane on disk, it can cause out-of-range access to
metadata or memory access overrun on metadata block buffers due to
overflow in sundry calculations.

Both lower limit and upper limit of metadata sizes are verified to
prevent these issues.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: Andreas Rohner <andreas.rohner@gmx.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/include/linux/nilfs2_fs.h b/include/linux/nilfs2_fs.h
index 1fb465f9baf2..ff3fea3194c6 100644
--- a/include/linux/nilfs2_fs.h
+++ b/include/linux/nilfs2_fs.h
@@ -82,6 +82,8 @@ struct nilfs_inode {
         __le32  i_pad;
 };
 
+#define NILFS_MIN_INODE_SIZE            128
+
 /**
  * struct nilfs_super_root - structure of super root
  * @sr_sum: check sum
@@ -482,6 +484,8 @@ struct nilfs_dat_entry {
         __le64 de_rsv;
 };
 
+#define NILFS_MIN_DAT_ENTRY_SIZE        32
+
 /**
  * struct nilfs_snapshot_list - snapshot list
  * @ssl_next: next checkpoint number on snapshot list
@@ -520,6 +524,8 @@ struct nilfs_checkpoint {
         struct nilfs_inode cp_ifile_inode;
 };
 
+#define NILFS_MIN_CHECKPOINT_SIZE       (64 + NILFS_MIN_INODE_SIZE)
+
 /* checkpoint flags */
 enum {
         NILFS_CHECKPOINT_SNAPSHOT,
@@ -615,6 +621,8 @@ struct nilfs_segment_usage {
         __le32 su_flags;
 };
 
+#define NILFS_MIN_SEGMENT_USAGE_SIZE    16
+
 /* segment usage flag */
 enum {
         NILFS_SEGMENT_USAGE_ACTIVE,