[PATCH net] net: fix harmonize_features() vs NETIF_F_HIGHDMA

[Eric Dumazet]

From: Eric Dumazet <eduma...@google.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 <eduma...@google.com>
Cc: Pravin Shelar <pshe...@ovn.org>
Reported-by: "Ashizuka, Yuusuke" <ashid...@jp.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;
 }