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

From: Hyunwoo Kim <[email-masked]>
Date: Fri, 8 May 2026 15:07:49 +0900

On Fri, May 08, 2026 at 01:57:15PM +0800, Qingfang Deng wrote:
> 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.

Thank you for the review.

I will submit a v2 patch.

Best regards,
Hyunwoo Kim

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