FAILED: patch "[PATCH] net: skbuff: don't skb_tx_error() the source skb in" failed to apply to 6.1-stable tree

FAILED: patch "[PATCH] net: skbuff: don't skb_tx_error() the source skb in" failed to apply to 6.1-stable tree

[gregkh]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 8ece906150128d5ec2462aabcc978c568433eca4
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026090320-disfigure-stony-5e76@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 8ece906150128d5ec2462aabcc978c568433eca4 Mon Sep 17 00:00:00 2001
From: Norbert Szetei <norbert@doyensec.com>
Date: Sat, 22 Aug 2026 11:13:47 +0200
Subject: [PATCH] net: skbuff: don't skb_tx_error() the source skb in
 skb_zerocopy()

skb_zerocopy() copies frags from @from into @to. On an
skb_orphan_frags() failure it calls skb_tx_error(@from), a destructive
operation on the source skb the copy helper does not own. That completes
@from's zerocopy uarg and clears SKBFL_ALL_ZEROCOPY, including the
SKBFL_SHARED_FRAG page-ownership marker.

Both callers already report the failure on their own drop path.
nfnetlink_queue does it at nla_put_failure, and Open vSwitch does it in
the flow-miss drop arm of ovs_dp_process_packet(), so nothing is lost by
dropping it here.

On Open vSwitch's OVS_ACTION_ATTR_USERSPACE path the skb is not freed on
this error: do_execute_actions() ignores output_userspace()'s return
value and, unless the upcall was the last action, keeps forwarding the
same skb through the flow's remaining actions. The uarg is completed
while that skb is still in flight, telling the producer its buffers are
free, and SKBFL_SHARED_FRAG is cleared on an skb the rest of the stack
still handles. That flag is what makes esp_input() call skb_cow_data()
instead of decrypting in place, so a later local ESP delivery can
decrypt over frags the skb does not own privately.

Leave error reporting to the callers.

Fixes: 36d5fe6a0007 ("core, nfqueue, openvswitch: Orphan frags in skb_zerocopy and handle errors")
Cc: stable@vger.kernel.org
Suggested-by: Ilya Maximets <i.maximets@ovn.org>
Signed-off-by: Norbert Szetei <norbert@doyensec.com>
Reviewed-by: Ilya Maximets <i.maximets@ovn.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/6E3A780D-FB87-421F-9964-B1D457D7D106@doyensec.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index d4382b68d56e..ab3d161247b9 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3914,7 +3914,6 @@ skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
 	skb_len_add(to, len + plen);
 
 	if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
-		skb_tx_error(from);
 		if (j > 0)
 			put_page(virt_to_head_page(from->head));
 		return -ENOMEM;

[PATCH 6.1.y] net: skbuff: don't skb_tx_error() the source skb in skb_zerocopy()

[Ilya Maximets]

From: Norbert Szetei <norbert@doyensec.com>

[ Upstream commit 8ece906150128d5ec2462aabcc978c568433eca4 ]

skb_zerocopy() copies frags from @from into @to. On an
skb_orphan_frags() failure it calls skb_tx_error(@from), a destructive
operation on the source skb the copy helper does not own. That completes
@from's zerocopy uarg and clears SKBFL_ALL_ZEROCOPY, including the
SKBFL_SHARED_FRAG page-ownership marker.

Both callers already report the failure on their own drop path.
nfnetlink_queue does it at nla_put_failure, and Open vSwitch does it in
the flow-miss drop arm of ovs_dp_process_packet(), so nothing is lost by
dropping it here.

On Open vSwitch's OVS_ACTION_ATTR_USERSPACE path the skb is not freed on
this error: do_execute_actions() ignores output_userspace()'s return
value and, unless the upcall was the last action, keeps forwarding the
same skb through the flow's remaining actions. The uarg is completed
while that skb is still in flight, telling the producer its buffers are
free, and SKBFL_SHARED_FRAG is cleared on an skb the rest of the stack
still handles. That flag is what makes esp_input() call skb_cow_data()
instead of decrypting in place, so a later local ESP delivery can
decrypt over frags the skb does not own privately.

Leave error reporting to the callers.

Fixes: 36d5fe6a0007 ("core, nfqueue, openvswitch: Orphan frags in skb_zerocopy and handle errors")
Cc: stable@vger.kernel.org
Suggested-by: Ilya Maximets <i.maximets@ovn.org>
Signed-off-by: Norbert Szetei <norbert@doyensec.com>
Reviewed-by: Ilya Maximets <i.maximets@ovn.org>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/6E3A780D-FB87-421F-9964-B1D457D7D106@doyensec.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
[ 7.2 and earlier do not have the put_page() call on the error path ]
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
---
 net/core/skbuff.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 6575a76a312e1..455fa9f83ec00 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3353,10 +3353,9 @@ skb_zerocopy(struct sk_buff *to, struct sk_buff *from, int len, int hlen)
 
 	skb_len_add(to, len + plen);
 
-	if (unlikely(skb_orphan_frags(from, GFP_ATOMIC))) {
-		skb_tx_error(from);
+	if (unlikely(skb_orphan_frags(from, GFP_ATOMIC)))
 		return -ENOMEM;
-	}
+
 	skb_zerocopy_clone(to, from, GFP_ATOMIC);
 
 	for (i = 0; i < skb_shinfo(from)->nr_frags; i++) {
-- 
2.55.0

Re: [PATCH 6.1.y] net: skbuff: don't skb_tx_error() the source skb in skb_zerocopy()

[Sasha Levin]

> skb_zerocopy() copies frags from @from into @to. On an
> skb_orphan_frags() failure it calls skb_tx_error(@from), a destructive
> operation on the source skb the copy helper does not own. That completes
> @from's zerocopy uarg and clears SKBFL_ALL_ZEROCOPY, including the
> SKBFL_SHARED_FRAG page-ownership marker.

Queued for 6.1, thanks.

-- 
Thanks,
Sasha