2020-05-01 14:14:21

by Colin King

Subject: [PATCH] net: stmmac: gmac5+: fix potential integer overflow on 32 bit multiply

From: Colin Ian King <[email protected]>

The multiplication of cfg->ctr[1] by 1000000000 is performed using a
32 bit multiplication (since cfg->ctr[1] is a u32) and this can lead
to a potential overflow. Fix this by making the constant a ULL to
ensure a 64 bit multiply occurs.

Fixes: 504723af0d85 ("net: stmmac: Add basic EST support for GMAC5+")
Addresses-Coverity: ("Unintentional integer overflow")
Signed-off-by: Colin Ian King <[email protected]>
---
drivers/net/ethernet/stmicro/stmmac/dwmac5.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac5.c b/drivers/net/ethernet/stmicro/stmmac/dwmac5.c
index 494c859b4ade..67ba67ed0cb9 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac5.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac5.c
@@ -624,7 +624,7 @@ int dwmac5_est_configure(void __iomem *ioaddr, struct stmmac_est *cfg,
total_offset += offset;
}

- total_ctr = cfg->ctr[0] + cfg->ctr[1] * 1000000000;
+ total_ctr = cfg->ctr[0] + cfg->ctr[1] * 1000000000ULL;
total_ctr += total_offset;

ctr_low = do_div(total_ctr, 1000000000);
--
2.25.1

2020-05-04 18:59:32

by David Miller

Subject: Re: [PATCH] net: stmmac: gmac5+: fix potential integer overflow on 32 bit multiply

From: Colin King <[email protected]>
Date: Fri, 1 May 2020 15:10:16 +0100

> From: Colin Ian King <[email protected]>
>
> The multiplication of cfg->ctr[1] by 1000000000 is performed using a
> 32 bit multiplication (since cfg->ctr[1] is a u32) and this can lead
> to a potential overflow. Fix this by making the constant a ULL to
> ensure a 64 bit multiply occurs.
>
> Fixes: 504723af0d85 ("net: stmmac: Add basic EST support for GMAC5+")
> Addresses-Coverity: ("Unintentional integer overflow")
> Signed-off-by: Colin Ian King <[email protected]>

Applied.