[PATCH] smbfs chroot issue (CVE-2006-1864)

Mark Moseley reported that a chroot environment on a SMB share can be
left via "cd ..\\".  Similar to CVE-2006-1863 issue with cifs, this fix
is for smbfs.

Steven French <sfrench@us.ibm.com> wrote:

Looks fine to me.  This should catch the slash on lookup or equivalent,
which will be all obvious paths of interest.

Signed-off-by: Chris Wright <chrisw@sous-sol.org>

fs/smbfs/dir.c

@@ -434,6 +434,11 @@ smb_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
 	if (dentry->d_name.len > SMB_MAXNAMELEN)
 		goto out;
 
+	/* Do not allow lookup of names with backslashes in */
+	error = -EINVAL;
+	if (memchr(dentry->d_name.name, '\\', dentry->d_name.len))
+		goto out;
+
 	lock_kernel();
 	error = smb_proc_getattr(dentry, &finfo);
 #ifdef SMBFS_PARANOIA