[PATCH for-next 2/9] IB/hfi1: Ensure dd->gi_mask can not be overflowed

[Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>]

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 <michael.j.ruhl-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
---
 drivers/infiniband/hw/hfi1/chip.c |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/drivers/infiniband/hw/hfi1/chip.c b/drivers/infiniband/hw/hfi1/chip.c
index aab107f..33fd7fe 100644
--- a/drivers/infiniband/hw/hfi1/chip.c
+++ b/drivers/infiniband/hw/hfi1/chip.c
@@ -12832,7 +12832,12 @@ 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;

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