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

[<gregkh@linuxfoundation.org>]

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 <stable@vger.kernel.org> know about it.


>From d8fd150fe3935e1692bf57c66691e17409ebb9c1 Mon Sep 17 00:00:00 2001
From: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
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 <konishi.ryusuke@lab.ntt.co.jp>

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.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/fs/nilfs2/btree.c
+++ b/fs/nilfs2/btree.c
@@ -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",
--- a/include/linux/nilfs2_fs.h
+++ b/include/linux/nilfs2_fs.h
@@ -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 konishi.ryusuke@lab.ntt.co.jp are

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