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    Subject[patch 07/37] Have ext2 reject file handles with bad inode numbers early.
    -stable review patch.  If anyone has any objections, please let us know.

    ------------------
    From: Neil Brown <neilb@suse.de>

    This prevents bad inode numbers from triggering errors in
    ext2_get_inode.


    Signed-off-by: Neil Brown <neilb@suse.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

    ---
    fs/ext2/super.c | 41 +++++++++++++++++++++++++++++++++++++++++
    1 file changed, 41 insertions(+)

    --- linux-2.6.17.11.orig/fs/ext2/super.c
    +++ linux-2.6.17.11/fs/ext2/super.c
    @@ -252,6 +252,46 @@ static struct super_operations ext2_sops
    #endif
    };

    +static struct dentry *ext2_get_dentry(struct super_block *sb, void *vobjp)
    +{
    + __u32 *objp = vobjp;
    + unsigned long ino = objp[0];
    + __u32 generation = objp[1];
    + struct inode *inode;
    + struct dentry *result;
    +
    + if (ino != EXT2_ROOT_INO && ino < EXT2_FIRST_INO(sb))
    + return ERR_PTR(-ESTALE);
    + if (ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
    + return ERR_PTR(-ESTALE);
    +
    + /* iget isn't really right if the inode is currently unallocated!!
    + * ext2_read_inode currently does appropriate checks, but
    + * it might be "neater" to call ext2_get_inode first and check
    + * if the inode is valid.....
    + */
    + inode = iget(sb, ino);
    + if (inode == NULL)
    + return ERR_PTR(-ENOMEM);
    + if (is_bad_inode(inode)
    + || (generation && inode->i_generation != generation)
    + ) {
    + /* we didn't find the right inode.. */
    + iput(inode);
    + return ERR_PTR(-ESTALE);
    + }
    + /* now to find a dentry.
    + * If possible, get a well-connected one
    + */
    + result = d_alloc_anon(inode);
    + if (!result) {
    + iput(inode);
    + return ERR_PTR(-ENOMEM);
    + }
    + return result;
    +}
    +
    +
    /* Yes, most of these are left as NULL!!
    * A NULL value implies the default, which works with ext2-like file
    * systems, but can be improved upon.
    @@ -259,6 +299,7 @@ static struct super_operations ext2_sops
    */
    static struct export_operations ext2_export_ops = {
    .get_parent = ext2_get_parent,
    + .get_dentry = ext2_get_dentry,
    };

    static unsigned long get_sb_block(void **data)
    --
    -
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