From 108bb2142e3a12c9ad625ad662973127a113ddc6 Mon Sep 17 00:00:00 2001 From: Jakub Kicinski Date: Wed, 2 Sep 2026 20:26:09 -0700 Subject: [PATCH] eth: nfp: drop the replaced rule from the list when reprogramming fails nfp_net_fs_add() replaces an existing rule by deleting it from the hardware, decrementing nn->fs.count and programming the new one. If nfp_net_fs_add_hw() fails the old entry stays on nn->fs.list - only the success path reaches list_replace() - so the list is one longer than nn->fs.count, and it advertises a rule whose hardware entry has already been torn down. nn->fs.count is what ETHTOOL_GRXCLSRLCNT reports, so userspace then sizes its buffer one entry short of what the GRXCLSRLALL walk wants to write. That used to overwrite one u32 past the allocation; since the walk is bounded it is a permanent -EMSGSIZE instead, as nothing ever resyncs the counter. Fixes: 9eb03bb1c035 ("nfp: add ethtool flow steering callbacks") Reviewed-by: Joe Damato Link: https://patch.msgid.link/20260903032611.3000029-4-kuba@kernel.org Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/netronome/nfp/nfp_net_ethtool.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/netronome/nfp/nfp_net_ethtool.c b/drivers/net/ethernet/netronome/nfp/nfp_net_ethtool.c index 9419e1ed8466..4e83637715e0 100644 --- a/drivers/net/ethernet/netronome/nfp/nfp_net_ethtool.c +++ b/drivers/net/ethernet/netronome/nfp/nfp_net_ethtool.c @@ -1703,8 +1703,14 @@ static int nfp_net_fs_add(struct nfp_net *nn, struct ethtool_rxnfc *cmd) nn->fs.count--; err = nfp_net_fs_add_hw(nn, new); - if (err) + if (err) { + /* mbox broken, adding the old rule back will + * likely also fail. + */ + list_del(&entry->node); + kfree(entry); goto err; + } nn->fs.count++; list_replace(&entry->node, &new->node);