From: Phillip Lougher Date: Wed, 2 Nov 2011 20:38:01 +0000 (-0700) Subject: hfs: fix hfs_find_init() sb->ext_tree NULL ptr oops X-Git-Tag: v2.6.27.60~32 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3db7e32f7521df6f9b64a9b04abb00dd11ca5735;p=thirdparty%2Fkernel%2Fstable.git 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. [WT: patch edited - 47f365eb57573 was missing from 2.6.27.x] 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 Signed-off-by: Willy Tarreau --- diff --git a/fs/hfs/btree.c b/fs/hfs/btree.c index 9b9d6395bad36..0609e710e4f50 100644 --- a/fs/hfs/btree.c +++ b/fs/hfs/btree.c @@ -45,11 +45,26 @@ struct hfs_btree *hfs_btree_open(struct super_block *sb, u32 id, btree_keycmp ke 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: