IB/hfi1: Validate the TID count before using it

Improve the safety of the code by validating the user supplied
tidcnt before use.

Reviewed-by: Mitko Haralanov <mitko.haralanov@intel.com>
Reviewed-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/hfi1/user_exp_rcv.c

@@ -579,6 +579,9 @@ int hfi1_user_exp_rcv_clear(struct file *fp, struct hfi1_tid_info *tinfo)
 	u32 *tidinfo;
 	unsigned tididx;
 
+	if (unlikely(tinfo->tidcnt > fd->tid_used))
+		return -EINVAL;
+
 	tidinfo = memdup_user((void __user *)(unsigned long)tinfo->tidlist,
 			      sizeof(tidinfo[0]) * tinfo->tidcnt);
 	if (IS_ERR(tidinfo))