net: check dev->gso_max_size in gso_features_check()

[ Upstream commit 24ab059d2ebd62fdccc43794796f6ffbabe49ebc ]

Some drivers might misbehave if TSO packets get too big.

GVE for instance uses a 16bit field in its TX descriptor,
and will do bad things if a packet is bigger than 2^16 bytes.

Linux TCP stack honors dev->gso_max_size, but there are
other ways for too big packets to reach an ndo_start_xmit()
handler : virtio_net, af_packet, GRO...

Add a generic check in gso_features_check() and fallback
to GSO when needed.

gso_max_size was added in the blamed commit.

Fixes: 82cc1a7a5687 ("[NET]: Add per-connection option to set max TSO frame size")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231219125331.4127498-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/core/dev.c b/net/core/dev.c
index 9bf90b2..e480afb 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3500,6 +3500,9 @@ static netdev_features_t gso_features_check(const struct sk_buff *skb,
        if (gso_segs > READ_ONCE(dev->gso_max_segs))
                return features & ~NETIF_F_GSO_MASK;
 
        if (gso_segs > READ_ONCE(dev->gso_max_segs))
                return features & ~NETIF_F_GSO_MASK;
 

+       if (unlikely(skb->len >= READ_ONCE(dev->gso_max_size)))
+               return features & ~NETIF_F_GSO_MASK;
+

        if (!skb_shinfo(skb)->gso_type) {
                skb_warn_bad_offload(skb);
                return features & ~NETIF_F_GSO_MASK;
        if (!skb_shinfo(skb)->gso_type) {
                skb_warn_bad_offload(skb);
                return features & ~NETIF_F_GSO_MASK;