From b97c0b521ae05d40e6541858600088a30f6dbe3a Mon Sep 17 00:00:00 2001 From: Colin Ian King Date: Fri, 7 Jun 2019 19:19:20 +0100 Subject: ixgbe: fix potential u32 overflow on shift 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 Acked-by: Jacob Keller Tested-by: Andrew Bowers Signed-off-by: Jeff Kirsher --- drivers/net/ethernet/intel/ixgbe/ixgbe_ptp.c | 14 ++++---------- 1 file changed, 4 insertions(+), 10 deletions(-) (limited to 'drivers') 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 -- cgit v1.2.3