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: 36d5fe6a0007 ("core, nfqueue, openvswitch: Orphan frags in skb_zerocopy
and handle errors")
Fixes: f4c50a4034e6 ("xfrm: esp: avoid in-place decrypt on shared skb frags")
Cc: [email protected]
Suggested-by: Ilya Maximets <[email protected]>
Signed-off-by: Norbert Szetei <[email protected]>
---
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
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