From b2d12101bff95c27960c69f3e54a98afdc205bb3 Mon Sep 17 00:00:00 2001 From: Colin Ian King Date: Fri, 16 Feb 2018 16:55:05 +0000 Subject: [PATCH] net: dsa: mv88e6xxx: avoid unintended sign extension on a 16 bit shift The shifting of timehi by 16 bits to the left will be promoted to a 32 bit signed int and then sign-extended to an u64. If the top bit of timehi is set then all then all the upper bits of ns end up as also being set because of the sign-extension. Fix this by making timehi and timelo u64. Also move the declaration of ns. Detected by CoverityScan, CID#1465288 ("Unintended sign extension") Fixes: c6fe0ad2c349 ("net: dsa: mv88e6xxx: add rx/tx timestamping support") Signed-off-by: Colin Ian King Signed-off-by: David S. Miller --- drivers/net/dsa/mv88e6xxx/hwtstamp.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/dsa/mv88e6xxx/hwtstamp.c b/drivers/net/dsa/mv88e6xxx/hwtstamp.c index b251d53..2149d33 100644 --- a/drivers/net/dsa/mv88e6xxx/hwtstamp.c +++ b/drivers/net/dsa/mv88e6xxx/hwtstamp.c @@ -293,7 +293,8 @@ static void mv88e6xxx_get_rxts(struct mv88e6xxx_chip *chip, struct sk_buff *skb, u16 reg, struct sk_buff_head *rxq) { - u16 buf[4] = { 0 }, status, timelo, timehi, seq_id; + u16 buf[4] = { 0 }, status, seq_id; + u64 ns, timelo, timehi; struct skb_shared_hwtstamps *shwt; int err; @@ -321,7 +322,7 @@ static void mv88e6xxx_get_rxts(struct mv88e6xxx_chip *chip, */ for ( ; skb; skb = skb_dequeue(rxq)) { if (mv88e6xxx_ts_valid(status) && seq_match(skb, seq_id)) { - u64 ns = timehi << 16 | timelo; + ns = timehi << 16 | timelo; mutex_lock(&chip->reg_lock); ns = timecounter_cyc2time(&chip->tstamp_tc, ns); -- 2.7.4