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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , linux-afs@lists.infradead.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, imv4bel@gmail.com Subject: Re: [PATCH] rxrpc: always copy skb on in-place decrypt to avoid pagecache aliasing Message-ID: References: <20260502211340.446927-1-n7l8m4@u.northwestern.edu> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260502211340.446927-1-n7l8m4@u.northwestern.edu> On Sat, May 02, 2026 at 09:13:40PM +0000, Ziyi Guo wrote: > skb_cloned() does not detect frag-level page sharing introduced by splice() > with MSG_SPLICE_PAGES. When such an skb reaches the rxrpc DATA path, > in-place decryption (rxkad/rxgk) writes plaintext into file > pagecache pages still aliased to the source file, leading to > corrupt the page cache of any readable file. > > Drop the skb_cloned() gate so skb_copy() is performed unconditionally > for DATA packets, severing the alias before decrypt. > > Fixes: d0d5c0cd1e71 ("rxrpc: Use skb_unshare() rather than skb_cow_data()") > Signed-off-by: Ziyi Guo > --- > net/rxrpc/call_event.c | 10 ++++++---- > 1 file changed, 6 insertions(+), 4 deletions(-) > > diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c > index fdd683261226..39d19a354172 100644 > --- a/net/rxrpc/call_event.c > +++ b/net/rxrpc/call_event.c > @@ -333,10 +333,12 @@ bool rxrpc_input_call_event(struct rxrpc_call *call) > saw_ack |= sp->hdr.type == RXRPC_PACKET_TYPE_ACK; > > if (sp->hdr.type == RXRPC_PACKET_TYPE_DATA && > - sp->hdr.securityIndex != 0 && > - skb_cloned(skb)) { > - /* Unshare the packet so that it can be > - * modified by in-place decryption. > + sp->hdr.securityIndex != 0) { > + /* Always unshare: skb_cloned() does not > + * detect frag-level page sharing introduced > + * by splice() with MSG_SPLICE_PAGES, so > + * in-place decryption could otherwise corrupt > + * the source file's page cache. > */ > struct sk_buff *nskb = skb_copy(skb, GFP_ATOMIC); > > -- > 2.34.1 > Hi, A patch for this issue has already been posted earlier: https://lore.kernel.org/all/afKV2zGR6rrelPC7@v4bel/ Best regards, Hyunwoo Kim