[PATCH] net: stmmac_tc: use 64-bit arithmetic instead of 32-bit

[PATCH] net: stmmac_tc: use 64-bit arithmetic instead of 32-bit

[Gustavo A. R. Silva]

Add suffix UL to constant 1024 in order to give the compiler complete
information about the proper arithmetic to use. Notice that this
constant is used in a context that expects an expression of type
u64 (64 bits, unsigned) and  following expressions are currently
being evaluated using 32-bit arithmetic:

qopt->idleslope * 1024 * ptr
qopt->hicredit * 1024 * 8
qopt->locredit * 1024 * 8

Addresses-Coverity-ID: 1470246 ("Unintentional integer overflow")
Addresses-Coverity-ID: 1470248 ("Unintentional integer overflow")
Addresses-Coverity-ID: 1470249 ("Unintentional integer overflow")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
index 0b0fca0..8fedc28 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c
@@ -321,7 +321,7 @@ static int tc_setup_cbs(struct stmmac_priv *priv,
 	speed_div = (priv->speed == SPEED_100) ? 100000 : 1000000;
 
 	/* Final adjustments for HW */
-	value = qopt->idleslope * 1024 * ptr;
+	value = qopt->idleslope * 1024UL * ptr;
 	do_div(value, speed_div);
 	priv->plat->tx_queues_cfg[queue].idle_slope = value & GENMASK(31, 0);
 
@@ -329,10 +329,10 @@ static int tc_setup_cbs(struct stmmac_priv *priv,
 	do_div(value, speed_div);
 	priv->plat->tx_queues_cfg[queue].send_slope = value & GENMASK(31, 0);
 
-	value = qopt->hicredit * 1024 * 8;
+	value = qopt->hicredit * 1024UL * 8;
 	priv->plat->tx_queues_cfg[queue].high_credit = value & GENMASK(31, 0);
 
-	value = qopt->locredit * 1024 * 8;
+	value = qopt->locredit * 1024UL * 8;
 	priv->plat->tx_queues_cfg[queue].low_credit = value & GENMASK(31, 0);
 
 	ret = stmmac_config_cbs(priv, priv->hw,
-- 
2.7.4

Re: [PATCH] net: stmmac_tc: use 64-bit arithmetic instead of 32-bit

[Jose Abreu]

On 02-07-2018 13:09, Gustavo A. R. Silva wrote:
> Add suffix UL to constant 1024 in order to give the compiler complete
> information about the proper arithmetic to use. Notice that this
> constant is used in a context that expects an expression of type
> u64 (64 bits, unsigned) and  following expressions are currently
> being evaluated using 32-bit arithmetic:
>
> qopt->idleslope * 1024 * ptr
> qopt->hicredit * 1024 * 8
> qopt->locredit * 1024 * 8
>
> Addresses-Coverity-ID: 1470246 ("Unintentional integer overflow")
> Addresses-Coverity-ID: 1470248 ("Unintentional integer overflow")
> Addresses-Coverity-ID: 1470249 ("Unintentional integer overflow")
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
>

Acked-by: Jose Abreu <joabreu@synopsys.com>

Thanks!

Best Regards,
Jose Miguel Abreu

Re: [PATCH] net: stmmac_tc: use 64-bit arithmetic instead of 32-bit

[David Miller]

From: "Gustavo A. R. Silva" <gustavo@embeddedor.com>
Date: Mon, 2 Jul 2018 07:09:32 -0500

> Add suffix UL to constant 1024 in order to give the compiler complete
> information about the proper arithmetic to use. Notice that this
> constant is used in a context that expects an expression of type
> u64 (64 bits, unsigned) and  following expressions are currently
> being evaluated using 32-bit arithmetic:
> 
> qopt->idleslope * 1024 * ptr
> qopt->hicredit * 1024 * 8
> qopt->locredit * 1024 * 8
> 
> Addresses-Coverity-ID: 1470246 ("Unintentional integer overflow")
> Addresses-Coverity-ID: 1470248 ("Unintentional integer overflow")
> Addresses-Coverity-ID: 1470249 ("Unintentional integer overflow")
> Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

Applied.