[PATCH] net: stmmac: fix maxmtu assignment to be within valid range

From: "Kweh, Hock Leong" <redacted>

There is no checking valid value of maxmtu when getting it from devicetree.
This resolution added the checking condition to ensure the assignment is
made within a valid range.

Signed-off-by: Kweh, Hock Leong <redacted>
---
 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 39eb7a6..683d59f 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -3319,7 +3319,8 @@ int stmmac_dvr_probe(struct device *device,
 		ndev->max_mtu = JUMBO_LEN;
 	else
 		ndev->max_mtu = SKB_MAX_HEAD(NET_SKB_PAD + NET_IP_ALIGN);
-	if (priv->plat->maxmtu < ndev->max_mtu)
+	if ((priv->plat->maxmtu < ndev->max_mtu) &&
+	    (priv->plat->maxmtu >= ndev->min_mtu))
 		ndev->max_mtu = priv->plat->maxmtu;
 
 	if (flow_ctrl)

-- 
1.7.9.5

On Thu, Jan 5, 2017 at 12:47 PM, Kweh, Hock Leong
[off-list ref] wrote:

From: "Kweh, Hock Leong" <redacted>

There is no checking valid value of maxmtu when getting it from devicetree.

'Device Tree' or 'device tree' ?

This resolution added the checking condition to ensure the assignment is
made within a valid range.

Perhaps add a warning message on else branch?

-- 
With Best Regards,
Andy Shevchenko

-----Original Message-----
From: Andy Shevchenko [mailto:andy.shevchenko@gmail.com]
Sent: Friday, January 06, 2017 5:07 AM
To: Kweh, Hock Leong <redacted>
Cc: David S. Miller <davem@davemloft.net>; Joao Pinto
[off-list ref]; Giuseppe CAVALLARO [off-list ref];
seraphin.bonnaffe@st.com; Jarod Wilson [off-list ref]; Alexandre
TORGUE [off-list ref]; Joachim Eastwood
[off-list ref]; Niklas Cassel [off-list ref]; Johan Hovold
[off-list ref]; Pavel Machek [off-list ref]; lars.persson@axis.com;
netdev [off-list ref]; LKML [off-list ref]
Subject: Re: [PATCH] net: stmmac: fix maxmtu assignment to be within valid
range

On Thu, Jan 5, 2017 at 12:47 PM, Kweh, Hock Leong
[off-list ref] wrote:

quoted

From: "Kweh, Hock Leong" <redacted>

There is no checking valid value of maxmtu when getting it from devicetree.

'Device Tree' or 'device tree' ?

Noted & Thanks. Submitting V2.

quoted

This resolution added the checking condition to ensure the assignment
is made within a valid range.

quoted

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 39eb7a6..683d59f 100644

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -3319,7 +3319,8 @@ int stmmac_dvr_probe(struct device *device,
                ndev->max_mtu = JUMBO_LEN;
        else
                ndev->max_mtu = SKB_MAX_HEAD(NET_SKB_PAD + NET_IP_ALIGN);
-       if (priv->plat->maxmtu < ndev->max_mtu)
+       if ((priv->plat->maxmtu < ndev->max_mtu) &&
+           (priv->plat->maxmtu >= ndev->min_mtu))
                ndev->max_mtu = priv->plat->maxmtu;

Perhaps add a warning message on else branch?

Noted & Thanks. Submitting V2.

--
With Best Regards,
Andy Shevchenko