[PATCH 6.1 54/69] net: dont touch dev->stats in BPF redirect paths

Greg Kroah-Hartman
2026-02-09T14:44:19Z

From: Jakub Kicinski <kuba@kernel.org>

[ Upstream commit fdf3f6800be36377e045e2448087f12132b88d2f ]

Gal reports that BPF redirect increments dev->stats.tx_errors
on failure. This is not correct, most modern drivers completely
ignore dev->stats so these drops will be invisible to the user.
Core code should use the dedicated core stats which are folded
into device stats in dev_get_stats().

Note that we're switching from tx_errors to tx_dropped.
Core only has tx_dropped, hence presumably users already expect
that counter to increment for "stack" Tx issues.

Reported-by: Gal Pressman <gal@nvidia.com>
Link: https://lore.kernel.org/c5df3b60-246a-4030-9c9a-0a35cd1ca924@nvidia.com
Fixes: b4ab31414970 ("bpf: Add redirect_neigh helper as redirect drop-in")
Acked-by: Martin KaFai Lau <martin.lau@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20260130033827.698841-1-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/core/filter.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/core/filter.c b/net/core/filter.c
index 305c38636b32b..e19bf63ad9a44 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2274,12 +2274,12 @@ static int __bpf_redirect_neigh_v6(struct sk_buff *skb, struct net_device *dev,

err = bpf_out_neigh_v6(net, skb, dev, nh);
if (unlikely(net_xmit_eval(err)))
- DEV_STATS_INC(dev, tx_errors);
+ dev_core_stats_tx_dropped_inc(dev);
else
ret = NET_XMIT_SUCCESS;
goto out_xmit;
out_drop:
- DEV_STATS_INC(dev, tx_errors);
+ dev_core_stats_tx_dropped_inc(dev);
kfree_skb(skb);
out_xmit:
return ret;
@@ -2382,12 +2382,12 @@ static int __bpf_redirect_neigh_v4(struct sk_buff *skb, struct net_device *dev,

err = bpf_out_neigh_v4(net, skb, dev, nh);
if (unlikely(net_xmit_eval(err)))
- DEV_STATS_INC(dev, tx_errors);
+ dev_core_stats_tx_dropped_inc(dev);
else
ret = NET_XMIT_SUCCESS;
goto out_xmit;
out_drop:
- DEV_STATS_INC(dev, tx_errors);
+ dev_core_stats_tx_dropped_inc(dev);
kfree_skb(skb);
out_xmit:
return ret;
--
2.51.0