[PATCH][V2] net: stmmac: ensure jumbo_frm error return is correctly checked for -ve value

[PATCH][V2] net: stmmac: ensure jumbo_frm error return is correctly checked for -ve value

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The current comparison of entry < 0 will never be true since entry is an
unsigned integer. Make entry an int to ensure -ve error return values
from the call to jumbo_frm are correctly being caught.

Detected by CoverityScan, CID#1238760 ("Macro compares unsigned to 0")

Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 68a188e74c54..3346a99ce4c4 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -2945,7 +2945,8 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
 	int i, csum_insertion = 0, is_jumbo = 0;
 	u32 queue = skb_get_queue_mapping(skb);
 	int nfrags = skb_shinfo(skb)->nr_frags;
-	unsigned int entry, first_entry;
+	int entry;
+	unsigned int first_entry;
 	struct dma_desc *desc, *first;
 	struct stmmac_tx_queue *tx_q;
 	unsigned int enh_desc;
-- 
2.11.0

Re: [PATCH][V2] net: stmmac: ensure jumbo_frm error return is correctly checked for -ve value

[Julia Lawall]

On Mon, 5 Jun 2017, Colin King wrote:

> From: Colin Ian King <colin.king@canonical.com>
>
> The current comparison of entry < 0 will never be true since entry is an
> unsigned integer. Make entry an int to ensure -ve error return values
> from the call to jumbo_frm are correctly being caught.

Perhaps it would be good to mention that the return value of jumbo_frm
is an int and that the subsequent computations on entry are all on small
values so there is no need for unsigned.

julia

>
> Detected by CoverityScan, CID#1238760 ("Macro compares unsigned to 0")
>
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> index 68a188e74c54..3346a99ce4c4 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
> @@ -2945,7 +2945,8 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev)
>  	int i, csum_insertion = 0, is_jumbo = 0;
>  	u32 queue = skb_get_queue_mapping(skb);
>  	int nfrags = skb_shinfo(skb)->nr_frags;
> -	unsigned int entry, first_entry;
> +	int entry;
> +	unsigned int first_entry;
>  	struct dma_desc *desc, *first;
>  	struct stmmac_tx_queue *tx_q;
>  	unsigned int enh_desc;
> --
> 2.11.0
>
> --
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Re: [PATCH][V2] net: stmmac: ensure jumbo_frm error return is correctly checked for -ve value

[David Miller]

From: Colin King <colin.king@canonical.com>
Date: Mon,  5 Jun 2017 10:04:52 +0100

> From: Colin Ian King <colin.king@canonical.com>
> 
> The current comparison of entry < 0 will never be true since entry is an
> unsigned integer. Make entry an int to ensure -ve error return values
> from the call to jumbo_frm are correctly being caught.
> 
> Detected by CoverityScan, CID#1238760 ("Macro compares unsigned to 0")
> 
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

I know Julia asked for more comments, but I'm going to apply this
as-is for now as it is correct.

Thanks Colin.