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    Subject[055/151] hfs: fix a potential buffer overflow
    2.6.32-stable review patch.  If anyone has any objections, please let us know.

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

    From: Amerigo Wang <amwang@redhat.com>

    commit ec81aecb29668ad71f699f4e7b96ec46691895b6 upstream.

    A specially-crafted Hierarchical File System (HFS) filesystem could cause
    a buffer overflow to occur in a process's kernel stack during a memcpy()
    call within the hfs_bnode_read() function (at fs/hfs/bnode.c:24). The
    attacker can provide the source buffer and length, and the destination
    buffer is a local variable of a fixed length. This local variable (passed
    as "&entry" from fs/hfs/dir.c:112 and allocated on line 60) is stored in
    the stack frame of hfs_bnode_read()'s caller, which is hfs_readdir().
    Because the hfs_readdir() function executes upon any attempt to read a
    directory on the filesystem, it gets called whenever a user attempts to
    inspect any filesystem contents.

    [amwang@redhat.com: modify this patch and fix coding style problems]
    Signed-off-by: WANG Cong <amwang@redhat.com>
    Cc: Eugene Teo <eteo@redhat.com>
    Cc: Roman Zippel <zippel@linux-m68k.org>
    Cc: Al Viro <viro@zeniv.linux.org.uk>
    Cc: Christoph Hellwig <hch@lst.de>
    Cc: Alexey Dobriyan <adobriyan@gmail.com>
    Cc: Dave Anderson <anderson@redhat.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    fs/hfs/catalog.c | 4 ++++
    fs/hfs/dir.c | 11 +++++++++++
    fs/hfs/super.c | 7 ++++++-
    3 files changed, 21 insertions(+), 1 deletion(-)

    --- a/fs/hfs/catalog.c
    +++ b/fs/hfs/catalog.c
    @@ -289,6 +289,10 @@ int hfs_cat_move(u32 cnid, struct inode
    err = hfs_brec_find(&src_fd);
    if (err)
    goto out;
    + if (src_fd.entrylength > sizeof(entry) || src_fd.entrylength < 0) {
    + err = -EIO;
    + goto out;
    + }

    hfs_bnode_read(src_fd.bnode, &entry, src_fd.entryoffset,
    src_fd.entrylength);
    --- a/fs/hfs/dir.c
    +++ b/fs/hfs/dir.c
    @@ -79,6 +79,11 @@ static int hfs_readdir(struct file *filp
    filp->f_pos++;
    /* fall through */
    case 1:
    + if (fd.entrylength > sizeof(entry) || fd.entrylength < 0) {
    + err = -EIO;
    + goto out;
    + }
    +
    hfs_bnode_read(fd.bnode, &entry, fd.entryoffset, fd.entrylength);
    if (entry.type != HFS_CDR_THD) {
    printk(KERN_ERR "hfs: bad catalog folder thread\n");
    @@ -109,6 +114,12 @@ static int hfs_readdir(struct file *filp
    err = -EIO;
    goto out;
    }
    +
    + if (fd.entrylength > sizeof(entry) || fd.entrylength < 0) {
    + err = -EIO;
    + goto out;
    + }
    +
    hfs_bnode_read(fd.bnode, &entry, fd.entryoffset, fd.entrylength);
    type = entry.type;
    len = hfs_mac2asc(sb, strbuf, &fd.key->cat.CName);
    --- a/fs/hfs/super.c
    +++ b/fs/hfs/super.c
    @@ -409,8 +409,13 @@ static int hfs_fill_super(struct super_b
    /* try to get the root inode */
    hfs_find_init(HFS_SB(sb)->cat_tree, &fd);
    res = hfs_cat_find_brec(sb, HFS_ROOT_CNID, &fd);
    - if (!res)
    + if (!res) {
    + if (fd.entrylength > sizeof(rec) || fd.entrylength < 0) {
    + res = -EIO;
    + goto bail;
    + }
    hfs_bnode_read(fd.bnode, &rec, fd.entryoffset, fd.entrylength);
    + }
    if (res) {
    hfs_find_exit(&fd);
    goto bail_no_root;



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