AZL-86366

In the Linux kernel, the following vulnerability has been resolved:

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

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

Extend the gate to also unshare when skbhasfraglist() or skbhassharedfrag() 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.