linux-kernel - [PATCH] Truncate UTS_RELEASE for rxrpc version

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Message-ID: <20230525211346.718562-1-Kenny.Ho@amd.com>
Date:   Thu, 25 May 2023 17:13:46 -0400
From:   Kenny Ho <Kenny.Ho@....com>
To:     David Laight <David.Laight@...lab.com>,
        Jakub Kicinski <kuba@...nel.org>, Andrew Lunn <andrew@...n.ch>,
        Marc Dionne <marc.dionne@...istor.com>,
        "Kenny Ho" <y2kenny@...il.com>,
        David Howells <dhowells@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        "Paolo Abeni" <pabeni@...hat.com>,
        "linux-afs@...ts.infradead.org" <linux-afs@...ts.infradead.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        <alexander.deucher@....com>
CC:     Kenny Ho <Kenny.Ho@....com>
Subject: [PATCH] Truncate UTS_RELEASE for rxrpc version

UTS_RELEASE has maximum length of 64 which can cause rxrpc_version to
exceed the 65 byte message limit.

Per https://web.mit.edu/kolya/afs/rx/rx-spec
"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 payload
containing a string that identifies the version of AFS software it is
running."

Current implementation causes compile error when WERROR is turned on and
when UTS_RELEASE exceed the length of 49 (making the version string more
than 64 characters.)

Signed-off-by: Kenny Ho <Kenny.Ho@....com>
---
 net/rxrpc/local_event.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/rxrpc/local_event.c b/net/rxrpc/local_event.c
index 19e929c7c38b..90af6fbb9266 100644
--- a/net/rxrpc/local_event.c
+++ b/net/rxrpc/local_event.c
@@ -16,8 +16,6 @@
 #include <generated/utsrelease.h>
 #include "ar-internal.h"
 
-static const char rxrpc_version_string[65] = "linux-" UTS_RELEASE " AF_RXRPC";
-
 /*
  * Reply to a version request
  */
@@ -30,6 +28,7 @@ static void rxrpc_send_version_request(struct rxrpc_local *local,
 	struct sockaddr_rxrpc srx;
 	struct msghdr msg;
 	struct kvec iov[2];
+	static char rxrpc_version_string[65];
 	size_t len;
 	int ret;
 
@@ -38,6 +37,12 @@ static void rxrpc_send_version_request(struct rxrpc_local *local,
 	if (rxrpc_extract_addr_from_skb(&srx, skb) < 0)
 		return;
 
+	if (!rxrpc_version_string[0])
+		snprintf(rxrpc_version_string,
+				sizeof(rxrpc_version_string),
+				"linux-%.49s AF_RXRPC",
+				UTS_RELEASE);
+
 	msg.msg_name	= &srx.transport;
 	msg.msg_namelen	= srx.transport_len;
 	msg.msg_control	= NULL;
-- 
2.25.1