The patch titled
From: plougher@xxxxxxxxxx (Phillip Lougher)
has been added to the -mm tree. Its filename is
hfs-fix-hfs_find_init-sb-ext_tree-null-ptr-oops.patch
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From: plougher@xxxxxxxxxx (Phillip Lougher)
Subject: hfs: fix hfs_find_init() sb->ext_tree NULL ptr oops
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 <clement.lecigne@xxxxxxxxxx>
Signed-off-by: Phillip Lougher <plougher@xxxxxxxxxx>
Cc: Jeff Mahoney <jeffm@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxx>
---
fs/hfs/btree.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff -puN fs/hfs/btree.c~hfs-fix-hfs_find_init-sb-ext_tree-null-ptr-oops fs/hfs/btree.c
--- a/fs/hfs/btree.c~hfs-fix-hfs_find_init-sb-ext_tree-null-ptr-oops
+++ a/fs/hfs/btree.c
@@ -46,11 +46,26 @@ struct hfs_btree *hfs_btree_open(struct
case HFS_EXT_CNID:
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;
break;
case HFS_CAT_CNID:
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;
break;
default:
@@ -59,11 +74,6 @@ struct hfs_btree *hfs_btree_open(struct
}
unlock_new_inode(tree->inode);
- 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))
_
Subject: From: plougher@xxxxxxxxxx (Phillip Lougher)
Patches currently in -mm which might be from clement.lecigne@xxxxxxxxxx are
hfs-fix-hfs_find_init-sb-ext_tree-null-ptr-oops.patch
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