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From:   Stephen Kitt <steve@sk2.org>
To:     "David S . Miller" <davem@davemloft.net>,
        Joe Perches <joe@perches.com>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, Stephen Kitt <steve@sk2.org>
Subject: [PATCH v2] net: Protect INET_ADDR_COOKIE on 32-bit architectures
Date:   Fri,  8 May 2020 14:04:57 +0200
Message-Id: <20200508120457.29422-1-steve@sk2.org>
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Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Commit c7228317441f ("net: Use a more standard macro for
INET_ADDR_COOKIE") added a __deprecated marker to the cookie name on
32-bit architectures, with the intent that the compiler would flag
uses of the name. However since commit 771c035372a0 ("deprecate the
'__deprecated' attribute warnings entirely and for good"),
__deprecated doesn't do anything and should be avoided.

This patch changes INET_ADDR_COOKIE to declare a dummy struct so that
any subsequent use of the cookie's name will in all likelihood break
the build. It also removes the __deprecated marker.

Signed-off-by: Stephen Kitt <steve@sk2.org>
---
Changes since v1:
  - use a dummy struct rather than a typedef

 include/net/inet_hashtables.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index ad64ba6a057f..889d9b00c905 100644
--- a/include/net/inet_hashtables.h
+++ b/include/net/inet_hashtables.h
@@ -301,8 +301,9 @@ static inline struct sock *inet_lookup_listener(struct net *net,
 	  ((__sk)->sk_bound_dev_if == (__sdif)))		&&	\
 	 net_eq(sock_net(__sk), (__net)))
 #else /* 32-bit arch */
+/* Break the build if anything tries to use the cookie's name. */
 #define INET_ADDR_COOKIE(__name, __saddr, __daddr) \
-	const int __name __deprecated __attribute__((unused))
+	struct {} __name __attribute__((unused))
 
 #define INET_MATCH(__sk, __net, __cookie, __saddr, __daddr, __ports, __dif, __sdif) \
 	(((__sk)->sk_portpair == (__ports))		&&		\
-- 
2.20.1