Subject: [PATCH 6.3 049/286] rxrpc: Truncate UTS_RELEASE for rxrpc version

From: Greg Kroah-Hartman <[email-masked]>
Date: Wed, 7 Jun 2023 22:12:28 +0200

From: David Howells <[email-masked]>

[ Upstream commit 020c69c1a793ed29d28793808eddd75210c858dd ]

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 payload
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 more
than 64 characters).

Fix this by generating the string during module initialisation and limiting
the UTS_RELEASE segment of the string does not exceed 49 chars.  We need to
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 <[email-masked]>
Link: https://lore.kernel.org/r/[email-masked]/
Signed-off-by: David Howells <[email-masked]>
Acked-by: Kenny Ho <[email-masked]>
cc: Marc Dionne <[email-masked]>
cc: Andrew Lunn <[email-masked]>
cc: David Laight <[email-masked]>
cc: "David S. Miller" <[email-masked]>
cc: Eric Dumazet <[email-masked]>
cc: Jakub Kicinski <[email-masked]>
cc: Paolo Abeni <[email-masked]>
cc: [email-masked]
cc: [email-masked]
Link: https://web.mit.edu/kolya/afs/rx/rx-spec [1]
Reviewed-by: Simon Horman <[email-masked]>
Reviewed-by: Jeffrey Altman <[email-masked]>
Link: https://lore.kernel.org/r/[email-masked]
Signed-off-by: Paolo Abeni <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 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 a6f0d29f35ef9..f5d1fc1266a5a 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -967,6 +967,7 @@ static int __init af_rxrpc_init(void)
 	BUILD_BUG_ON(sizeof(struct rxrpc_skb_priv) > sizeof_field(struct sk_buff, cb));
 
 	ret = -ENOMEM;
+	rxrpc_gen_version_string();
 	rxrpc_call_jar = 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 5d44dc08f66d0..e8e14c6f904d9 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_connection *, 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 5e69ea6b233da..993c69f97488c 100644
--- a/net/rxrpc/local_event.c
+++ b/net/rxrpc/local_event.c
@@ -16,7 +16,16 @@
 #include <generated/utsrelease.h>
 #include "ar-internal.h"
 
-static const char rxrpc_version_string[65] = "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
-- 
2.39.2