From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
The u32 variable rem is being shifted using u32 arithmetic however
it is being passed to div_u64 that expects the expression to be a u64.
The 32 bit shift may potentially overflow, so cast rem to a u64 before
shifting to avoid this. Also remove comment about overflow.
Addresses-Coverity: ("Unintentional integer overflow")
Fixes: cd4583206990 ("ixgbe: implement support for SDP/PPS output on X550 hardware")
Fixes: 68d9676fc04e ("ixgbe: fix PTP SDP pin setup on X540 hardware")
Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
---
V2: update comment
---
drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c
index 2c4d327fcc2e..0be13a90ff79 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c
@@ -205,11 +205,8 @@ static void ixgbe_ptp_setup_sdp_X540(struct ixgbe_adapter *adapter)
*/
rem = (NS_PER_SEC - rem);
- /* Adjust the clock edge to align with the next full second. This
- * assumes that the cycle counter shift is small enough to avoid
- * overflowing when shifting the remainder.
- */
- clock_edge += div_u64((rem << cc->shift), cc->mult);
+ /* Adjust the clock edge to align with the next full second. */
+ clock_edge += div_u64(((u64)rem << cc->shift), cc->mult);
trgttiml = (u32)clock_edge;
trgttimh = (u32)(clock_edge >> 32);
@@ -291,11 +288,8 @@ static void ixgbe_ptp_setup_sdp_X550(struct ixgbe_adapter *adapter)
*/
rem = (NS_PER_SEC - rem);
- /* Adjust the clock edge to align with the next full second. This
- * assumes that the cycle counter shift is small enough to avoid
- * overflowing when shifting the remainder.
- */
- clock_edge += div_u64((rem << cc->shift), cc->mult);
+ /* Adjust the clock edge to align with the next full second. */
+ clock_edge += div_u64(((u64)rem << cc->shift), cc->mult);
/* X550 hardware stores the time in 32bits of 'billions of cycles' and
* 32bits of 'cycles'. There's no guarantee that cycles represents
--
2.20.1
