FAILED: patch "[PATCH] rxrpc: Also unshare DATA/RESPONSE packets when paged frags" failed to apply to 6.6-stable tree

The patch below does not apply to the 6.6-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 <[email protected]>.

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-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x aa54b1d27fe0c2b78e664a34fd0fdf7cd1960d71
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026051113-sponge-uproar-1d30@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

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

From aa54b1d27fe0c2b78e664a34fd0fdf7cd1960d71 Mon Sep 17 00:00:00 2001
From: Hyunwoo Kim <[email protected]>
Date: Fri, 8 May 2026 17:53:09 +0900
Subject: [PATCH] rxrpc: Also unshare DATA/RESPONSE packets when paged frags
are present

The DATA-packet handler in rxrpc_input_call_event() and the RESPONSE handler in rxrpc_verify_response() copy the skb to a linear one before calling into the security ops only when skb_cloned() is true. An skb that is not cloned but still carries externally-owned paged fragments (e.g. SKBFL_SHARED_FRAG set by splice() into a UDP socket via __ip_append_data, or a chained skb_has_frag_list()) falls through to the in-place decryption path, which binds the frag pages directly into the AEAD/skcipher SGL via skb_to_sgvec().

Extend the gate to also unshare when skb_has_frag_list() or skb_has_shared_frag() is true. This catches the splice-loopback vector and other externally-shared frag sources while preserving the zero-copy fast path for skbs whose frags are kernel-private (e.g. NIC page_pool RX, GRO). The OOM/trace handling already in place is reused.

index fdd683261226..2b19b252225e 100644
@@ -334,7 +334,9 @@ bool rxrpc_input_call_event(struct rxrpc_call *call)
 
 			if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
 			    sp->hdr.securityIndex != 0 &&
-			    skb_cloned(skb)) {
+			    (skb_cloned(skb) ||
+			     skb_has_frag_list(skb) ||
+			     skb_has_shared_frag(skb))) {
 				/* Unshare the packet so that it can be
 				 * modified by in-place decryption.
 				 */

index a2130d25aaa9..442414d90ba1 100644
@@ -245,7 +245,8 @@ static int rxrpc_verify_response(struct rxrpc_connection *conn,
 {
 	int ret;
 
-	if (skb_cloned(skb)) {
+	if (skb_cloned(skb) || skb_has_frag_list(skb) ||
+	    skb_has_shared_frag(skb)) {
 		/* Copy the packet if shared so that we can do in-place
 		 * decryption.
 		 */

From: David Howells <[email protected]>

The security operations that verify the RESPONSE packets decrypt bits of it in place - however, the sk_buff may be shared with a packet sniffer, which would lead to the sniffer seeing an apparently corrupt packet (actually decrypted).

Fix this by handing a copy of the packet off to the specific security handler if the packet was cloned.

---
NOTE:
Pls apply these pathes after commit in stable queue like:
(HEAD -> for-stable-queue) rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present
rxrpc: Fix conn-level packet handling to unshare RESPONSE packets (refs/patches/for-stable-queue/rxrpc-fix-rxrpc_input_call_event-to-only-unshare-dat.patch)
Subject: rxrpc: Fix rxrpc_input_call_event() to only unshare DATA packets
---

---
 net/rxrpc/conn_event.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

index 82cc72123c9c9..6dcfaed1f7485 100644
@@ -226,6 +226,33 @@ static void rxrpc_call_is_secure(struct rxrpc_call *call)
 		rxrpc_notify_socket(call);
 }
 
+static int rxrpc_verify_response(struct rxrpc_connection *conn,
+				 struct sk_buff *skb)
+{
+	int ret;
+
+	if (skb_cloned(skb)) {
+		/* Copy the packet if shared so that we can do in-place
+		 * decryption.
+		 */
+		struct sk_buff *nskb = skb_copy(skb, GFP_NOFS);
+
+		if (nskb) {
+			rxrpc_new_skb(nskb, rxrpc_skb_new_unshared);
+			ret = conn->security->verify_response(conn, nskb);
+			rxrpc_free_skb(nskb, rxrpc_skb_put_response_copy);
+		} else {
+			/* OOM - Drop the packet. */
+			rxrpc_see_skb(skb, rxrpc_skb_see_unshare_nomem);
+			ret = -ENOMEM;
+		}
+	} else {
+		ret = conn->security->verify_response(conn, skb);
+	}
+
+	return ret;
+}
+
 /*
  * connection-level Rx packet processor
  */

@@ -253,7 +280,7 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
 		}
 		spin_unlock(&conn->state_lock);
 
-		ret = conn->security->verify_response(conn, skb);
+		ret = rxrpc_verify_response(conn, skb);
 		if (ret < 0)
 			return ret;
 

2.30.2

From: David Howells <[email protected]>

The security operations that verify the RESPONSE packets decrypt bits of it in place - however, the sk_buff may be shared with a packet sniffer, which would lead to the sniffer seeing an apparently corrupt packet (actually decrypted).

Fix this by handing a copy of the packet off to the specific security handler if the packet was cloned.

---
NOTE:
Pls apply these pathes after commit in stable queue like:
(HEAD -> for-stable-queue) rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present
rxrpc: Fix conn-level packet handling to unshare RESPONSE packets (refs/patches/for-stable-queue/rxrpc-fix-rxrpc_input_call_event-to-only-unshare-dat.patch)
Subject: rxrpc: Fix rxrpc_input_call_event() to only unshare DATA packets
---

---
 net/rxrpc/conn_event.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

index 82cc72123c9c9..6dcfaed1f7485 100644
@@ -226,6 +226,33 @@ static void rxrpc_call_is_secure(struct rxrpc_call *call)
 		rxrpc_notify_socket(call);
 }
 
+static int rxrpc_verify_response(struct rxrpc_connection *conn,
+				 struct sk_buff *skb)
+{
+	int ret;
+
+	if (skb_cloned(skb)) {
+		/* Copy the packet if shared so that we can do in-place
+		 * decryption.
+		 */
+		struct sk_buff *nskb = skb_copy(skb, GFP_NOFS);
+
+		if (nskb) {
+			rxrpc_new_skb(nskb, rxrpc_skb_new_unshared);
+			ret = conn->security->verify_response(conn, nskb);
+			rxrpc_free_skb(nskb, rxrpc_skb_put_response_copy);
+		} else {
+			/* OOM - Drop the packet. */
+			rxrpc_see_skb(skb, rxrpc_skb_see_unshare_nomem);
+			ret = -ENOMEM;
+		}
+	} else {
+		ret = conn->security->verify_response(conn, skb);
+	}
+
+	return ret;
+}
+
 /*
  * connection-level Rx packet processor
  */

@@ -253,7 +280,7 @@ static int rxrpc_process_event(struct rxrpc_connection *conn,
 		}
 		spin_unlock(&conn->state_lock);
 
-		ret = conn->security->verify_response(conn, skb);
+		ret = rxrpc_verify_response(conn, skb);
 		if (ret < 0)
 			return ret;
 

2.30.2

From: Hyunwoo Kim <[email protected]>

The DATA-packet handler in rxrpc_input_call_event() and the RESPONSE handler in rxrpc_verify_response() copy the skb to a linear one before calling into the security ops only when skb_cloned() is true. An skb that is not cloned but still carries externally-owned paged fragments (e.g. SKBFL_SHARED_FRAG set by splice() into a UDP socket via __ip_append_data, or a chained skb_has_frag_list()) falls through to the in-place decryption path, which binds the frag pages directly into the AEAD/skcipher SGL via skb_to_sgvec().

Extend the gate to also unshare when skb_has_frag_list() or skb_has_shared_frag() is true. This catches the splice-loopback vector and other externally-shared frag sources while preserving the zero-copy fast path for skbs whose frags are kernel-private (e.g. NIC page_pool RX, GRO). The OOM/trace handling already in place is reused.

---
 net/rxrpc/call_event.c | 4 +++-
 net/rxrpc/conn_event.c | 3 ++-
 2 files changed, 5 insertions(+), 2 deletions(-)

index d6dfc7c08cf04..07b2d81145d62 100644
@@ -461,7 +461,9 @@ bool rxrpc_input_call_event(struct rxrpc_call *call, struct sk_buff *skb)
 
 		if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA &&
 		    sp->hdr.securityIndex != 0 &&
-		    skb_cloned(skb)) {
+		    (skb_cloned(skb) ||
+		     skb_has_frag_list(skb) ||
+		     skb_has_shared_frag(skb))) {
 			/* Unshare the packet so that it can be modified by
 			 * in-place decryption.
 			 */

index 6dcfaed1f7485..3a58fb9210383 100644
@@ -231,7 +231,8 @@ static int rxrpc_verify_response(struct rxrpc_connection *conn,
 {
 	int ret;
 
-	if (skb_cloned(skb)) {
+	if (skb_cloned(skb) || skb_has_frag_list(skb) ||
+	    skb_has_shared_frag(skb)) {
 		/* Copy the packet if shared so that we can do in-place
 		 * decryption.
 		 */

2.30.2