lkml.org 
[lkml]   [2011]   [Dec]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[36/53] hfs: fix hfs_find_init() sb->ext_tree NULL ptr oops
    3.1-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Phillip Lougher <plougher@redhat.com>

    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 <clement.lecigne@netasq.com>
    Signed-off-by: Phillip Lougher <plougher@redhat.com>
    Cc: Jeff Mahoney <jeffm@suse.com>
    Cc: Christoph Hellwig <hch@lst.de>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Moritz Mühlenhoff <jmm@inutil.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    fs/hfs/btree.c | 20 +++++++++++++++-----
    1 file changed, 15 insertions(+), 5 deletions(-)

    --- a/fs/hfs/btree.c
    +++ b/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))

    --
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2011-12-16 21:07    [W:0.036 / U:2.260 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site