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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 In-Reply-To: <20230525211346.718562-1-Kenny.Ho@amd.com> References: <20230525211346.718562-1-Kenny.Ho@amd.com> To: Kenny Ho Cc: dhowells@redhat.com, David Laight , Jakub Kicinski , Andrew Lunn , Marc Dionne , "Kenny Ho" , "David S. Miller" , Eric Dumazet , "Paolo Abeni" , "linux-afs@lists.infradead.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , alexander.deucher@amd.com Subject: Re: [PATCH] Truncate UTS_RELEASE for rxrpc version MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <223249.1685052554.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Thu, 25 May 2023 23:09:14 +0100 Message-ID: <223250.1685052554@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Kenny Ho wrote: > @@ -30,6 +28,7 @@ static void rxrpc_send_version_request(struct rxrpc_lo= cal *local, > struct sockaddr_rxrpc srx; > struct msghdr msg; > struct kvec iov[2]; > + static char rxrpc_version_string[65]; > size_t len; > int ret; > = That's not thread-safe. If you have multiple endpoints each one of them c= ould be overwriting the string at the same time. We can't guarantee that one wouldn't corrupt the other. There's also no need to reprint it every time; just once during module ini= t will do. How about the attached patch instead? David --- rxrpc: Truncate UTS_RELEASE for rxrpc version UTS_RELEASE has a maximum length of 64 which can cause rxrpc_version to exceed the 65 byte message limit. Per the rx spec[1]: "If a server receives a packet with a type value of 13= , and the client-initiated flag set, it should respond with a 65-byte payloa= d containing a string that identifies the version of AFS software it is running." The current implementation causes a compile error when WERROR is turned on and/or UTS_RELEASE exceeds the length of 49 (making the version string mor= e than 64 characters). Fix this by generating the string during module initialisation and limitin= g the UTS_RELEASE segment of the string does not exceed 49 chars. We need t= o make sure that the 64 bytes includes "linux-" at the front and " AF_RXRPC"= at the back as this may be used in pattern matching. Fixes: 44ba06987c0b ("RxRPC: Handle VERSION Rx protocol packets") Reported-by: Kenny Ho Link: https://lore.kernel.org/r/20230523223944.691076-1-Kenny.Ho@amd.com/ Signed-off-by: David Howells Link: https://web.mit.edu/kolya/afs/rx/rx-spec [1] cc: Marc Dionne cc: Andrew Lunn cc: David Laight cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: linux-afs@lists.infradead.org cc: netdev@vger.kernel.org --- net/rxrpc/af_rxrpc.c | 1 + net/rxrpc/ar-internal.h | 1 + net/rxrpc/local_event.c | 11 ++++++++++- 3 files changed, 12 insertions(+), 1 deletion(-) diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c index 31f738d65f1c..da0b3b5157d5 100644 --- a/net/rxrpc/af_rxrpc.c +++ b/net/rxrpc/af_rxrpc.c @@ -980,6 +980,7 @@ static int __init af_rxrpc_init(void) BUILD_BUG_ON(sizeof(struct rxrpc_skb_priv) > sizeof_field(struct sk_buff= , cb)); = ret =3D -ENOMEM; + rxrpc_gen_version_string(); rxrpc_call_jar =3D kmem_cache_create( "rxrpc_call_jar", sizeof(struct rxrpc_call), 0, SLAB_HWCACHE_ALIGN, NULL); diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index 5d44dc08f66d..e8e14c6f904d 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -1068,6 +1068,7 @@ int rxrpc_get_server_data_key(struct rxrpc_connectio= n *, const void *, time64_t, /* * local_event.c */ +void rxrpc_gen_version_string(void); void rxrpc_send_version_request(struct rxrpc_local *local, struct rxrpc_host_header *hdr, struct sk_buff *skb); diff --git a/net/rxrpc/local_event.c b/net/rxrpc/local_event.c index 5e69ea6b233d..993c69f97488 100644 --- a/net/rxrpc/local_event.c +++ b/net/rxrpc/local_event.c @@ -16,7 +16,16 @@ #include #include "ar-internal.h" = -static const char rxrpc_version_string[65] =3D "linux-" UTS_RELEASE " AF_= RXRPC"; +static char rxrpc_version_string[65]; // "linux-" UTS_RELEASE " AF_RXRPC"= ; + +/* + * Generate the VERSION packet string. + */ +void rxrpc_gen_version_string(void) +{ + snprintf(rxrpc_version_string, sizeof(rxrpc_version_string), + "linux-%.49s AF_RXRPC", UTS_RELEASE); +} = /* * Reply to a version request