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[165.124.184.136]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-8b538b1d833sm78281496d6.10.2026.05.02.14.13.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 May 2026 14:13:50 -0700 (PDT) From: Ziyi Guo To: David Howells , Marc Dionne , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman Cc: linux-afs@lists.infradead.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Ziyi Guo Subject: [PATCH] rxrpc: always copy skb on in-place decrypt to avoid pagecache aliasing Date: Sat, 2 May 2026 21:13:40 +0000 Message-Id: <20260502211340.446927-1-n7l8m4@u.northwestern.edu> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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 |=3D sp->hdr.type =3D=3D RXRPC_PACKET_TYPE_ACK; =20 if (sp->hdr.type =3D=3D RXRPC_PACKET_TYPE_DATA && - sp->hdr.securityIndex !=3D 0 && - skb_cloned(skb)) { - /* Unshare the packet so that it can be - * modified by in-place decryption. + sp->hdr.securityIndex !=3D 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 =3D skb_copy(skb, GFP_ATOMIC); =20 --=20 2.34.1