netdev - [PATCH AUTOSEL 6.5 15/45] net: Use sockaddr_storage for getsockopt(SO

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Date: Fri,  8 Sep 2023 14:12:56 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Kuniyuki Iwashima <kuniyu@...zon.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Willem de Bruijn <willemb@...gle.com>,
	"David S . Miller" <davem@...emloft.net>,
	Sasha Levin <sashal@...nel.org>,
	kuba@...nel.org,
	pabeni@...hat.com,
	alexander@...alicyn.com,
	leitao@...ian.org,
	lucien.xin@...il.com,
	dhowells@...hat.com,
	kernelxing@...cent.com,
	andriy.shevchenko@...ux.intel.com,
	netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 6.5 15/45] net: Use sockaddr_storage for getsockopt(SO_PEERNAME).

From: Kuniyuki Iwashima <kuniyu@...zon.com>

[ Upstream commit 8936bf53a091ad6a34b480c22002f1cb2422ab38 ]

Commit df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") started
applying strict rules to standard string functions.

It does not work well with conventional socket code around each protocol-
specific sockaddr_XXX struct, which is cast from sockaddr_storage and has
a bigger size than fortified functions expect.  See these commits:

 commit 06d4c8a80836 ("af_unix: Fix fortify_panic() in unix_bind_bsd().")
 commit ecb4534b6a1c ("af_unix: Terminate sun_path when bind()ing pathname socket.")
 commit a0ade8404c3b ("af_packet: Fix warning of fortified memcpy() in packet_getname().")

We must cast the protocol-specific address back to sockaddr_storage
to call such functions.

However, in the case of getsockaddr(SO_PEERNAME), the rationale is a bit
unclear as the buffer is defined by char[128] which is the same size as
sockaddr_storage.

Let's use sockaddr_storage explicitly.

Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
Reviewed-by: Willem de Bruijn <willemb@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/core/sock.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index c9cffb7acbeae..a80b6b8633edc 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1823,14 +1823,14 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
 
 	case SO_PEERNAME:
 	{
-		char address[128];
+		struct sockaddr_storage address;
 
-		lv = sock->ops->getname(sock, (struct sockaddr *)address, 2);
+		lv = sock->ops->getname(sock, (struct sockaddr *)&address, 2);
 		if (lv < 0)
 			return -ENOTCONN;
 		if (lv < len)
 			return -EINVAL;
-		if (copy_to_sockptr(optval, address, len))
+		if (copy_to_sockptr(optval, &address, len))
 			return -EFAULT;
 		goto lenout;
 	}
-- 
2.40.1