netdev - [PATCH net] net: fix harmonize_features() vs NETIF_F

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Message-ID: <1484770337.13165.120.camel@edumazet-glaptop3.roam.corp.google.com>
Date:   Wed, 18 Jan 2017 12:12:17 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Pravin Shelar <pshelar@....org>, David Miller <davem@...emloft.net>
Cc:     "Ashizuka, Yuusuke" <ashiduka@...fujitsu.com>,
        Andy Duan <fugang.duan@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Pravin B Shelar <pshelar@...ira.com>
Subject: [PATCH net] net: fix harmonize_features() vs NETIF_F_HIGHDMA

From: Eric Dumazet <edumazet@...gle.com>

Ashizuka reported a highmem oddity and sent a patch for freescale
fec driver.

But the problem root cause is that core networking stack
must ensure no skb with highmem fragment is ever sent through
a device that does not assert NETIF_F_HIGHDMA in its features.

We need to call illegal_highdma() from harmonize_features()
regardless of CSUM checks.

Fixes: ec5f06156423 ("net: Kill link between CSUM and SG features.")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: Pravin Shelar <pshelar@....org>
Reported-by: "Ashizuka, Yuusuke" <ashiduka@...fujitsu.com>
---
 net/core/dev.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 07b307b0b414730688b64fdb2295b0fa1b721e51..7f218e095361520d11c243d650e053321ea7274f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2795,9 +2795,9 @@ static netdev_features_t harmonize_features(struct sk_buff *skb,
 	if (skb->ip_summed != CHECKSUM_NONE &&
 	    !can_checksum_protocol(features, type)) {
 		features &= ~(NETIF_F_CSUM_MASK | NETIF_F_GSO_MASK);
-	} else if (illegal_highdma(skb->dev, skb)) {
-		features &= ~NETIF_F_SG;
 	}
+	if (illegal_highdma(skb->dev, skb))
+		features &= ~NETIF_F_SG;
 
 	return features;
 }