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Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells To: netdev@vger.kernel.org cc: dhowells@redhat.com, Jeffrey Altman , kafs-testing+fedora36_64checkkafs-build-306@auristor.com, Marc Dionne , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH net] rxrpc: Fix potential race in error handling in afs_make_call() MIME-Version: 1.0 Content-ID: <228969.1682114626.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Fri, 21 Apr 2023 23:03:46 +0100 Message-ID: <228970.1682114626@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" =20 If the rxrpc call set up by afs_make_call() receives an error whilst it is transmitting the request, there's the possibility that it may get to the point the rxrpc call is ended (after the error_kill_call label) just as the call is queued for async processing. This could manifest itself as call->rxcall being seen as NULL in afs_deliver_to_call() when it tries to lock the call. Fix this by splitting rxrpc_kernel_end_call() into a function to shut down an rxrpc call and a function to release the caller's reference and calling the latter only when we get to afs_put_call(). Reported-by: Jeffrey Altman Signed-off-by: David Howells Tested-by: kafs-testing+fedora36_64checkkafs-build-306@auristor.com cc: Marc Dionne cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: linux-afs@lists.infradead.org cc: netdev@vger.kernel.org --- Documentation/networking/rxrpc.rst | 17 ++++++++++++----- fs/afs/rxrpc.c | 9 ++++----- include/net/af_rxrpc.h | 3 ++- net/rxrpc/af_rxrpc.c | 37 +++++++++++++++++++++++++-------= ----- net/rxrpc/rxperf.c | 3 ++- 5 files changed, 45 insertions(+), 24 deletions(-) diff --git a/Documentation/networking/rxrpc.rst b/Documentation/networking/= rxrpc.rst index ec1323d92c96..c318ac5eb66f 100644 --- a/Documentation/networking/rxrpc.rst +++ b/Documentation/networking/rxrpc.rst @@ -848,14 +848,21 @@ The kernel interface functions are as follows: returned. The caller now holds a reference on this and it must be properly ended. =20 - (#) End a client call:: + (#) Shut down a client call:: =20 - void rxrpc_kernel_end_call(struct socket *sock, + void rxrpc_kernel_shutdown_call(struct socket *sock, + struct rxrpc_call *call); + + This is used to shut down a previously begun call. The user_call_ID = is + expunged from AF_RXRPC's knowledge and will not be seen again in + association with the specified call. + + (#) Release the ref on a client call:: + + void rxrpc_kernel_put_call(struct socket *sock, struct rxrpc_call *call); =20 - This is used to end a previously begun call. The user_call_ID is exp= unged - from AF_RXRPC's knowledge and will not be seen again in association w= ith - the specified call. + This is used to release the caller's ref on an rxrpc call. =20 (#) Send data through a call:: =20 diff --git a/fs/afs/rxrpc.c b/fs/afs/rxrpc.c index 7817e2b860e5..e08b850c3e6d 100644 --- a/fs/afs/rxrpc.c +++ b/fs/afs/rxrpc.c @@ -179,7 +179,8 @@ void afs_put_call(struct afs_call *call) ASSERT(call->type->name !=3D NULL); =20 if (call->rxcall) { - rxrpc_kernel_end_call(net->socket, call->rxcall); + rxrpc_kernel_shutdown_call(net->socket, call->rxcall); + rxrpc_kernel_put_call(net->socket, call->rxcall); call->rxcall =3D NULL; } if (call->type->destructor) @@ -420,10 +421,8 @@ void afs_make_call(struct afs_addr_cursor *ac, struct = afs_call *call, gfp_t gfp) * The call, however, might be queued on afs_async_calls and we need to * make sure we don't get any more notifications that might requeue it. */ - if (call->rxcall) { - rxrpc_kernel_end_call(call->net->socket, call->rxcall); - call->rxcall =3D NULL; - } + if (call->rxcall) + rxrpc_kernel_shutdown_call(call->net->socket, call->rxcall); if (call->async) { if (cancel_work_sync(&call->async_work)) afs_put_call(call); diff --git a/include/net/af_rxrpc.h b/include/net/af_rxrpc.h index ba717eac0229..01a35e113ab9 100644 --- a/include/net/af_rxrpc.h +++ b/include/net/af_rxrpc.h @@ -57,7 +57,8 @@ int rxrpc_kernel_recv_data(struct socket *, struct rxrpc_= call *, struct iov_iter *, size_t *, bool, u32 *, u16 *); bool rxrpc_kernel_abort_call(struct socket *, struct rxrpc_call *, u32, int, enum rxrpc_abort_reason); -void rxrpc_kernel_end_call(struct socket *, struct rxrpc_call *); +void rxrpc_kernel_shutdown_call(struct socket *sock, struct rxrpc_call *ca= ll); +void rxrpc_kernel_put_call(struct socket *sock, struct rxrpc_call *call); void rxrpc_kernel_get_peer(struct socket *, struct rxrpc_call *, struct sockaddr_rxrpc *); bool rxrpc_kernel_get_srtt(struct socket *, struct rxrpc_call *, u32 *); diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c index 9022071c55e3..ebe5b2906a59 100644 --- a/net/rxrpc/af_rxrpc.c +++ b/net/rxrpc/af_rxrpc.c @@ -341,31 +341,44 @@ static void rxrpc_dummy_notify_rx(struct sock *sk, st= ruct rxrpc_call *rxcall, } =20 /** - * rxrpc_kernel_end_call - Allow a kernel service to end a call it was usi= ng + * rxrpc_kernel_shutdown_call - Allow a kernel service to shut down a call= it was using * @sock: The socket the call is on * @call: The call to end * - * Allow a kernel service to end a call it was using. The call must be + * Allow a kernel service to shut down a call it was using. The call must= be * complete before this is called (the call should be aborted if necessary= ). */ -void rxrpc_kernel_end_call(struct socket *sock, struct rxrpc_call *call) +void rxrpc_kernel_shutdown_call(struct socket *sock, struct rxrpc_call *ca= ll) { _enter("%d{%d}", call->debug_id, refcount_read(&call->ref)); =20 mutex_lock(&call->user_mutex); - rxrpc_release_call(rxrpc_sk(sock->sk), call); - - /* Make sure we're not going to call back into a kernel service */ - if (call->notify_rx) { - spin_lock(&call->notify_lock); - call->notify_rx =3D rxrpc_dummy_notify_rx; - spin_unlock(&call->notify_lock); + if (!test_bit(RXRPC_CALL_RELEASED, &call->flags)) { + rxrpc_release_call(rxrpc_sk(sock->sk), call); + + /* Make sure we're not going to call back into a kernel service */ + if (call->notify_rx) { + spin_lock(&call->notify_lock); + call->notify_rx =3D rxrpc_dummy_notify_rx; + spin_unlock(&call->notify_lock); + } } - mutex_unlock(&call->user_mutex); +} +EXPORT_SYMBOL(rxrpc_kernel_shutdown_call); + +/** + * rxrpc_kernel_put_call - Release a reference to a call + * @sock: The socket the call is on + * @call: The call to put + * + * Drop the application's ref on an rxrpc call. + */ +void rxrpc_kernel_put_call(struct socket *sock, struct rxrpc_call *call) +{ rxrpc_put_call(call, rxrpc_call_put_kernel); } -EXPORT_SYMBOL(rxrpc_kernel_end_call); +EXPORT_SYMBOL(rxrpc_kernel_put_call); =20 /** * rxrpc_kernel_check_life - Check to see whether a call is still alive diff --git a/net/rxrpc/rxperf.c b/net/rxrpc/rxperf.c index 4a2e90015ca7..085e7892d310 100644 --- a/net/rxrpc/rxperf.c +++ b/net/rxrpc/rxperf.c @@ -342,7 +342,8 @@ static void rxperf_deliver_to_call(struct work_struct *= work) call_complete: rxperf_set_call_complete(call, ret, remote_abort); /* The call may have been requeued */ - rxrpc_kernel_end_call(rxperf_socket, call->rxcall); + rxrpc_kernel_shutdown_call(rxperf_socket, call->rxcall); + rxrpc_kernel_put_call(rxperf_socket, call->rxcall); cancel_work(&call->work); kfree(call); }