Subject: Re: [PATCH net] rxrpc: Also unshare DATA/RESPONSE packets when paged frags are present

From: Qingfang Deng <[email-masked]>
Date: Fri, 8 May 2026 13:57:15 +0800

On Thu, 30 Apr 2026 08:35:55 +0900, Hyunwoo Kim wrote:
> 
> 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: d0d5c0cd1e71 ("rxrpc: Use skb_unshare() rather than skb_cow_data()")
> Signed-off-by: Hyunwoo Kim <[email-masked]>
> ---
>  net/rxrpc/call_event.c | 2 +-
>  net/rxrpc/conn_event.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c
> index fdd683261226..6c924ef55208 100644
> --- a/net/rxrpc/call_event.c
> +++ b/net/rxrpc/call_event.c
> @@ -334,7 +334,7 @@ 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->data_len)) {

It's recommended to use skb_is_nonlinear() instead of open-coding
skb->data_len.

>  				/* Unshare the packet so that it can be
>  				 * modified by in-place decryption.
>  				 */
> diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c
> index a2130d25aaa9..eab7c5f2517a 100644
> --- a/net/rxrpc/conn_event.c
> +++ b/net/rxrpc/conn_event.c
> @@ -245,7 +245,7 @@ static int rxrpc_verify_response(struct rxrpc_connection *conn,
>  {
>  	int ret;
>  
> -	if (skb_cloned(skb)) {
> +	if (skb_cloned(skb) || skb->data_len) {

Ditto.

>  		/* Copy the packet if shared so that we can do in-place
>  		 * decryption.
>  		 */

Regards,
Qingfang