path: root/fs
diff options
authorPhillip Lougher <>2011-11-02 13:38:01 -0700
committerGreg Kroah-Hartman <>2011-12-21 12:58:32 -0800
commit9f0f2bb728f4e87568f89a5603f7d3b76ef6a3b9 (patch)
tree4afb269d0546bef6fe963efd9a9c307678016b29 /fs
parentd02ab857b278eb3a232daf85f78af0252044a728 (diff)
hfs: fix hfs_find_init() sb->ext_tree NULL ptr oops
commit 434a964daa14b9db083ce20404a4a2add54d037a upstream. Clement Lecigne reports a filesystem which causes a kernel oops in hfs_find_init() trying to dereference sb->ext_tree which is NULL. This proves to be because the filesystem has a corrupted MDB extent record, where the extents file does not fit into the first three extents in the file record (the first blocks). In hfs_get_block() when looking up the blocks for the extent file (HFS_EXT_CNID), it fails the first blocks special case, and falls through to the extent code (which ultimately calls hfs_find_init()) which is in the process of being initialised. Hfs avoids this scenario by always having the extents b-tree fitting into the first blocks (the extents B-tree can't have overflow extents). The fix is to check at mount time that the B-tree fits into first blocks, i.e. fail if HFS_I(inode)->alloc_blocks >= HFS_I(inode)->first_blocks Note, the existing commit 47f365eb57573 ("hfs: fix oops on mount with corrupted btree extent records") becomes subsumed into this as a special case, but only for the extents B-tree (HFS_EXT_CNID), it is perfectly acceptable for the catalog B-Tree file to grow beyond three extents, with the remaining extent descriptors in the extents overfow. This fixes CVE-2011-2203 Reported-by: Clement LECIGNE <> Signed-off-by: Phillip Lougher <> Cc: Jeff Mahoney <> Cc: Christoph Hellwig <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <> Cc: Moritz Mühlenhoff <> Signed-off-by: Greg Kroah-Hartman <>
Diffstat (limited to 'fs')
1 files changed, 15 insertions, 5 deletions
diff --git a/fs/hfs/btree.c b/fs/hfs/btree.c
index 3ebc437736fe..1cbdeea1db44 100644
--- a/fs/hfs/btree.c
+++ b/fs/hfs/btree.c
@@ -46,11 +46,26 @@ struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id, btree_keycmp ke
hfs_inode_read_fork(tree->inode, mdb->drXTExtRec, mdb->drXTFlSize,
mdb->drXTFlSize, be32_to_cpu(mdb->drXTClpSiz));
+ if (HFS_I(tree->inode)->alloc_blocks >
+ HFS_I(tree->inode)->first_blocks) {
+ printk(KERN_ERR "hfs: invalid btree extent records\n");
+ unlock_new_inode(tree->inode);
+ goto free_inode;
+ }
tree->inode->i_mapping->a_ops = &hfs_btree_aops;
hfs_inode_read_fork(tree->inode, mdb->drCTExtRec, mdb->drCTFlSize,
mdb->drCTFlSize, be32_to_cpu(mdb->drCTClpSiz));
+ if (!HFS_I(tree->inode)->first_blocks) {
+ printk(KERN_ERR "hfs: invalid btree extent records "
+ "(0 size).\n");
+ unlock_new_inode(tree->inode);
+ goto free_inode;
+ }
tree->inode->i_mapping->a_ops = &hfs_btree_aops;
@@ -59,11 +74,6 @@ struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id, btree_keycmp ke
- if (!HFS_I(tree->inode)->first_blocks) {
- printk(KERN_ERR "hfs: invalid btree extent records (0 size).\n");
- goto free_inode;
- }
mapping = tree->inode->i_mapping;
page = read_mapping_page(mapping, 0, NULL);
if (IS_ERR(page))