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net: dsa: mv88e6xxx: avoid unintended sign extension on a 16 bit shift

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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 <colin.king@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Colin Ian King 2018-02-16 16:55:05 +00:00 committed by David S. Miller
parent 75efa06f45
commit b2d12101bf
1 changed files with 3 additions and 2 deletions
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5
drivers/net/dsa/mv88e6xxx/hwtstamp.c
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@ -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);