Patch "nilfs2: fix sanity check of btree level in nilfs_btree_root_broken()" has been added to the 4.0-stable tree

This is a note to let you know that I've just added the patch titled

nilfs2: fix sanity check of btree level in nilfs_btree_root_broken()

to the 4.0-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
nilfs2-fix-sanity-check-of-btree-level-in-nilfs_btree_root_broken.patch
and it can be found in the queue-4.0 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ryusuke Konishi <[email protected]>
Date: Tue, 5 May 2015 16:24:00 -0700
Subject: nilfs2: fix sanity check of btree level in nilfs_btree_root_broken()

From: Ryusuke Konishi <[email protected]>

commit d8fd150fe3935e1692bf57c66691e17409ebb9c1 upstream.

The range check for b-tree level parameter in nilfs_btree_root_broken() is wrong; it accepts the case of "level == NILFS_BTREE_LEVEL_MAX" even though the level is limited to values in the range of 0 to (NILFS_BTREE_LEVEL_MAX - 1).

Since the level parameter is read from storage device and used to index nilfs_btree_path array whose element count is NILFS_BTREE_LEVEL_MAX, it can cause memory overrun during btree operations if the boundary value is set to the level parameter on device.

This fixes the broken sanity check and adds a comment to clarify that the upper bound NILFS_BTREE_LEVEL_MAX is exclusive.

---
 fs/nilfs2/btree.c         |    2 +-
 include/linux/nilfs2_fs.h |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

@@ -388,7 +388,7 @@ static int nilfs_btree_root_broken(const
 	nchildren = nilfs_btree_node_get_nchildren(node);
 
 	if (unlikely(level < NILFS_BTREE_LEVEL_NODE_MIN ||
-		     level > NILFS_BTREE_LEVEL_MAX ||
+		     level >= NILFS_BTREE_LEVEL_MAX ||
 		     nchildren < 0 ||
 		     nchildren > NILFS_BTREE_ROOT_NCHILDREN_MAX)) {
 		pr_crit("NILFS: bad btree root (inode number=%lu): level = %d, flags = 0x%x, nchildren = %d\n",

@@ -460,7 +460,7 @@ struct nilfs_btree_node {
 /* level */
 #define NILFS_BTREE_LEVEL_DATA          0
 #define NILFS_BTREE_LEVEL_NODE_MIN      (NILFS_BTREE_LEVEL_DATA + 1)
-#define NILFS_BTREE_LEVEL_MAX           14
+#define NILFS_BTREE_LEVEL_MAX           14	/* Max level (exclusive) */
 
 /**
  * struct nilfs_palloc_group_desc - block group descriptor

Patches currently in stable-queue which might be from [email protected] are

queue-4.0/nilfs2-fix-sanity-check-of-btree-level-in-nilfs_btree_root_broken.patch