From: Ido Schimmel <idosch@nvidia.com>
To: Eric Dumazet <edumazet@google.com>
Cc: "David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>, David Ahern <dsahern@kernel.org>,
netdev@vger.kernel.org, eric.dumazet@gmail.com
Subject: Re: [PATCH net-next] gre: fix ERSPAN o_flags race/corruption in xmit and fill_info
Date: Wed, 17 Jun 2026 09:34:21 +0300 [thread overview]
Message-ID: <20260617063421.GA948096@shredder> (raw)
In-Reply-To: <20260615140333.3161072-1-edumazet@google.com>
On Mon, Jun 15, 2026 at 02:03:33PM +0000, Eric Dumazet wrote:
> @@ -692,7 +689,7 @@ static netdev_tx_t ipgre_xmit(struct sk_buff *skb,
> tunnel->parms.o_flags)))
> goto free_skb;
>
> - __gre_xmit(skb, dev, tnl_params, skb->protocol);
> + __gre_xmit(skb, dev, tnl_params, skb->protocol, tunnel->parms.o_flags);
> return NETDEV_TX_OK;
>
> free_skb:
> @@ -705,6 +702,7 @@ static netdev_tx_t erspan_xmit(struct sk_buff *skb,
> struct net_device *dev)
> {
> struct ip_tunnel *tunnel = netdev_priv(dev);
> + IP_TUNNEL_DECLARE_FLAGS(flags);
> bool truncate = false;
> __be16 proto;
>
> @@ -728,10 +726,12 @@ static netdev_tx_t erspan_xmit(struct sk_buff *skb,
> truncate = true;
> }
>
> + ip_tunnel_flags_copy(flags, tunnel->parms.o_flags);
> +
> /* Push ERSPAN header */
> if (tunnel->erspan_ver == 0) {
> proto = htons(ETH_P_ERSPAN);
> - __clear_bit(IP_TUNNEL_SEQ_BIT, tunnel->parms.o_flags);
> + __clear_bit(IP_TUNNEL_SEQ_BIT, flags);
> } else if (tunnel->erspan_ver == 1) {
> erspan_build_header(skb, ntohl(tunnel->parms.o_key),
> tunnel->index,
> @@ -746,8 +746,8 @@ static netdev_tx_t erspan_xmit(struct sk_buff *skb,
> goto free_skb;
> }
>
> - __clear_bit(IP_TUNNEL_KEY_BIT, tunnel->parms.o_flags);
> - __gre_xmit(skb, dev, &tunnel->parms.iph, proto);
> + __clear_bit(IP_TUNNEL_KEY_BIT, flags);
> + __gre_xmit(skb, dev, &tunnel->parms.iph, proto, flags);
> return NETDEV_TX_OK;
>
> free_skb:
> @@ -776,7 +776,7 @@ static netdev_tx_t gre_tap_xmit(struct sk_buff *skb,
> if (skb_cow_head(skb, dev->needed_headroom))
> goto free_skb;
>
> - __gre_xmit(skb, dev, &tunnel->parms.iph, htons(ETH_P_TEB));
> + __gre_xmit(skb, dev, &tunnel->parms.iph, htons(ETH_P_TEB), tunnel->parms.o_flags);
Eric, did you see the feedback from Sashiko [1]?
WDYT about aligning ipgre and gretap with erspan and passing a copy of
the output flags to __gre_xmit() instead of passing
'tunnel->parms.o_flags' directly?
The mismatch between the output flags and the tunnel header length is a
different issue (pre-existing).
[1] https://sashiko.dev/#/patchset/20260615140333.3161072-1-edumazet%40google.com
> return NETDEV_TX_OK;
>
> free_skb:
prev parent reply other threads:[~2026-06-17 6:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-15 14:03 [PATCH net-next] gre: fix ERSPAN o_flags race/corruption in xmit and fill_info Eric Dumazet
2026-06-17 6:34 ` Ido Schimmel [this message]
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