Commit d8fd150f authored May 05, 2015 by Ryusuke Konishi Committed by Linus Torvalds May 05, 2015

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



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>

parent 05836c37

fs/nilfs2/btree.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -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",

include/linux/nilfs2_fs.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -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

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