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[78.141.71.213]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4999d078517sm103942915e9.5.2026.08.18.01.47.48 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 18 Aug 2026 01:47:49 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3826.700.81.1.4\)) Subject: [PATCH net v3 3/3] net: skbuff: don't touch shared zerocopy state in skb_tx_error() From: Norbert Szetei In-Reply-To: Date: Tue, 18 Aug 2026 10:47:37 +0200 Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Aaron Conole , Eelco Chaudron , Ilya Maximets , Steffen Klassert , Kuan-Ting Chen , "Michael S. Tsirkin" , linux-kernel@vger.kernel.org, dev@openvswitch.org, Jongmin Jang Content-Transfer-Encoding: 7bit Message-Id: <45B00A1C-A331-4982-8317-592EEA59426A@doyensec.com> References: To: netdev@vger.kernel.org X-Mailer: Apple Mail (2.3826.700.81.1.4) skb_tx_error() completes the zerocopy uarg and clears SKBFL_ALL_ZEROCOPY, and skb_zcopy_downgrade_managed() clears SKBFL_MANAGED_FRAG_REFS. Both live in skb_shinfo(), which every clone shares, while the caller only owns the reference it is about to drop. Through a clone it tells the producer its pages are free and drops SKBFL_SHARED_FRAG for an skb that is still in flight. Open vSwitch reaches this with a non-last OVS_ACTION_ATTR_RECIRC: clone_execute() sends a skb_clone() into ovs_dp_process_packet() while do_execute_actions() keeps forwarding the original, and skb_clone() does not privatise the frags here -- skb_orphan_frags() returns early on SKBFL_DONT_ORPHAN. A flow miss on the clone then strips the marker from the packet still being forwarded, and a later local ESP delivery decrypts in place over frags it does not own privately. Skip it for a cloned skb. Nothing is lost: skb_release_data() clears the zerocopy state once the last reference to the shared data goes. Fixes: 25121173f7b1 ("skb: api to report errors for zero copy skbs") Cc: stable@vger.kernel.org Suggested-by: Ilya Maximets Signed-off-by: Norbert Szetei Tested-by: Jongmin Jang --- net/core/skbuff.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index db62ed6e04b9..04776a112334 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -1417,10 +1417,13 @@ EXPORT_SYMBOL(skb_dump); * * Report xmit error if a device callback is tracking this skb. * skb must be freed afterwards. + * + * Does nothing for a cloned skb: the zerocopy state lives in + * skb_shinfo(), which the clones share. */ void skb_tx_error(struct sk_buff *skb) { - if (skb) { + if (skb && !skb_cloned(skb)) { skb_zcopy_downgrade_managed(skb); skb_zcopy_clear(skb, true); } -- 2.55.0