Commit b97c0b52 authored by Colin Ian King's avatar Colin Ian King Committed by Jeff Kirsher

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: cd458320 ("ixgbe: implement support for SDP/PPS output on X550 hardware")
Fixes: 68d9676f ("ixgbe: fix PTP SDP pin setup on X540 hardware")
Signed-off-by: default avatarColin Ian King <colin.king@canonical.com>
Acked-by: default avatarJacob Keller <jacob.e.keller@intel.com>
Tested-by: default avatarAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: default avatarJeff Kirsher <jeffrey.t.kirsher@intel.com>
parent 92924064
...@@ -205,11 +205,8 @@ static void ixgbe_ptp_setup_sdp_X540(struct ixgbe_adapter *adapter) ...@@ -205,11 +205,8 @@ static void ixgbe_ptp_setup_sdp_X540(struct ixgbe_adapter *adapter)
*/ */
rem = (NS_PER_SEC - rem); rem = (NS_PER_SEC - rem);
/* Adjust the clock edge to align with the next full second. This /* Adjust the clock edge to align with the next full second. */
* assumes that the cycle counter shift is small enough to avoid clock_edge += div_u64(((u64)rem << cc->shift), cc->mult);
* overflowing when shifting the remainder.
*/
clock_edge += div_u64((rem << cc->shift), cc->mult);
trgttiml = (u32)clock_edge; trgttiml = (u32)clock_edge;
trgttimh = (u32)(clock_edge >> 32); trgttimh = (u32)(clock_edge >> 32);
...@@ -291,11 +288,8 @@ static void ixgbe_ptp_setup_sdp_X550(struct ixgbe_adapter *adapter) ...@@ -291,11 +288,8 @@ static void ixgbe_ptp_setup_sdp_X550(struct ixgbe_adapter *adapter)
*/ */
rem = (NS_PER_SEC - rem); rem = (NS_PER_SEC - rem);
/* Adjust the clock edge to align with the next full second. This /* Adjust the clock edge to align with the next full second. */
* assumes that the cycle counter shift is small enough to avoid clock_edge += div_u64(((u64)rem << cc->shift), cc->mult);
* overflowing when shifting the remainder.
*/
clock_edge += div_u64((rem << cc->shift), cc->mult);
/* X550 hardware stores the time in 32bits of 'billions of cycles' and /* X550 hardware stores the time in 32bits of 'billions of cycles' and
* 32bits of 'cycles'. There's no guarantee that cycles represents * 32bits of 'cycles'. There's no guarantee that cycles represents
......
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