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nilfs2: fix potential memory overrun on inode

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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: 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 2015-02-27 15:51:56 -08:00 committed by Linus Torvalds
parent 586a1a125e
commit 957ed60b53
1 changed files with 44 additions and 3 deletions
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47
fs/nilfs2/btree.c
View File

@ -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)