rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present

cve CVE-2026-43500
commit-author Hyunwoo Kim <imv4bel@gmail.com>
commit -
commit-source https://lore.kernel.org/all/afKV2zGR6rrelPC7@v4bel
upstream-diff |
	The conn_event.c hunk is dropped entirely. Upstream wraps the
	conn->security->verify_response() call inside a new
	rxrpc_verify_response() function that copies non-linear skbs before
	in-place decryption. This kernel doesn't have that wrapper; the
	security op is called directly from rxrpc_process_event(), so there
	is no call site to patch. The call_event.c hunk applies as-is.

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 paged fragments (skb->data_len != 0)
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 so that any skb with non-linear data is also copied,
ensuring the security handler always operates on a fully linear skb.
The OOM/trace handling already in place is reused.

Fixes: d0d5c0c ("rxrpc: Use skb_unshare() rather than skb_cow_data()")
	Signed-off-by: Hyunwoo Kim <imv4bel@gmail.com>
(cherry picked from commit 544687651fe57721c5e4e76380ed8ef8fdfdc98b)
	Signed-off-by: Sultan Alsawaf <sultan@ciq.com>

Author: kerneltoast

net/rxrpc/call_event.c

@@ -347,7 +347,7 @@ 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->data_len)) {
 			/* Unshare the packet so that it can be
 			 * modified by in-place decryption.
 			 */