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

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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>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Ryusuke Konishi 2015-05-05 16:24:00 -07:00 committed by Linus Torvalds
parent 05836c378c
commit d8fd150fe3
2 changed files with 2 additions and 2 deletions
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2
fs/nilfs2/btree.c
View file

@ -388,7 +388,7 @@ static int nilfs_btree_root_broken(const struct nilfs_btree_node *node,
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",

2
include/linux/nilfs2_fs.h
View file

@ -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