IB/hfi1: Ensure dd->gi_mask can not be overflowed

As the code stands today the array access in remap_intr() is OK. To
future proof the code though we should explicitly check to ensure the
index value is not outside of the valid range. This is not a straight
forward calculation so err on the side of caution.

Reviewed-by: Michael J. Ruhl <[email protected]>
Signed-off-by: Dennis Dalessandro <[email protected]>
Signed-off-by: Doug Ledford <[email protected]>

Author: Dennis Dalessandro

drivers/infiniband/hw/hfi1/chip.c

@@ -12847,7 +12847,12 @@ static void remap_intr(struct hfi1_devdata *dd, int isrc, int msix_intr)
 	/* clear from the handled mask of the general interrupt */
 	m = isrc / 64;
 	n = isrc % 64;
-	dd->gi_mask[m] &= ~((u64)1 << n);
+	if (likely(m < CCE_NUM_INT_CSRS)) {
+		dd->gi_mask[m] &= ~((u64)1 << n);
+	} else {
+		dd_dev_err(dd, "remap interrupt err\n");
+		return;
+	}
 
 	/* direct the chip source to the given MSI-X interrupt */
 	m = isrc / 8;