Commit 957ed60b authored by Ryusuke Konishi's avatar Ryusuke Konishi Committed by Linus Torvalds
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nilfs2: fix potential memory overrun on inode 



Each inode of nilfs2 stores a root node of a b-tree, and it turned out to
have a memory overrun issue:

Each b-tree node of nilfs2 stores a set of key-value pairs and the number
of them (in "bn_nchildren" member of nilfs_btree_node struct), as well as
a few other "bn_*" members.

Since the value of "bn_nchildren" is used for operations on the key-values
within the b-tree node, it can cause memory access overrun if a large
number is incorrectly set to "bn_nchildren".

For instance, nilfs_btree_node_lookup() function determines the range of
binary search with it, and too large "bn_nchildren" leads
nilfs_btree_node_get_key() in that function to overrun.

As for intermediate b-tree nodes, this is prevented by a sanity check
performed when each node is read from a drive, however, no sanity check
has been done for root nodes stored in inodes.

This patch fixes the issue by adding missing sanity check against b-tree
root nodes so that it's called when on-memory inodes are read from ifile,
inode metadata file.

Signed-off-by: default avatarRyusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 586a1a12

fs/nilfs2/btree.c

+44 −3
Original line number Diff line number Diff line
@@ -31,6 +31,8 @@ 
#include "alloc.h"

#include "dat.h"



static void __nilfs_btree_init(struct nilfs_bmap *bmap);



static struct nilfs_btree_path *nilfs_btree_alloc_path(void)

{

	struct nilfs_btree_path *path;
@@ -368,6 +370,34 @@ static int nilfs_btree_node_broken(const struct nilfs_btree_node *node, 
	return ret;

}



/**

 * nilfs_btree_root_broken - verify consistency of btree root node

 * @node: btree root node to be examined

 * @ino: inode number

 *

 * Return Value: If node is broken, 1 is returned. Otherwise, 0 is returned.

 */

static int nilfs_btree_root_broken(const struct nilfs_btree_node *node,

				   unsigned long ino)

{

	int level, flags, nchildren;

	int ret = 0;



	level = nilfs_btree_node_get_level(node);

	flags = nilfs_btree_node_get_flags(node);

	nchildren = nilfs_btree_node_get_nchildren(node);



	if (unlikely(level < NILFS_BTREE_LEVEL_NODE_MIN ||

		     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",

			ino, level, flags, nchildren);

		ret = 1;

	}

	return ret;

}



int nilfs_btree_broken_node_block(struct buffer_head *bh)

{

	int ret;
@@ -1713,7 +1743,7 @@ nilfs_btree_commit_convert_and_insert(struct nilfs_bmap *btree, 


	/* convert and insert */

	dat = NILFS_BMAP_USE_VBN(btree) ? nilfs_bmap_get_dat(btree) : NULL;

	nilfs_btree_init(btree);

	__nilfs_btree_init(btree);

	if (nreq != NULL) {

		nilfs_bmap_commit_alloc_ptr(btree, dreq, dat);

		nilfs_bmap_commit_alloc_ptr(btree, nreq, dat);
@@ -2294,12 +2324,23 @@ static const struct nilfs_bmap_operations nilfs_btree_ops_gc = { 
	.bop_gather_data	=	NULL,

};



int nilfs_btree_init(struct nilfs_bmap *bmap)

static void __nilfs_btree_init(struct nilfs_bmap *bmap)

{

	bmap->b_ops = &nilfs_btree_ops;

	bmap->b_nchildren_per_block =

		NILFS_BTREE_NODE_NCHILDREN_MAX(nilfs_btree_node_size(bmap));

	return 0;

}



int nilfs_btree_init(struct nilfs_bmap *bmap)

{

	int ret = 0;



	__nilfs_btree_init(bmap);



	if (nilfs_btree_root_broken(nilfs_btree_get_root(bmap),

				    bmap->b_inode->i_ino))

		ret = -EIO;

	return ret;

}



void nilfs_btree_init_gc(struct nilfs_bmap *bmap)

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