linux-kernel - [PATCH AUTOSEL for 3.18 028/101] caif: Add sockaddr length check before accessing sa

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Message-ID: <20180409003505.164715-28-alexander.levin@microsoft.com>
Date:   Mon, 9 Apr 2018 00:35:37 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Mateusz Jurczyk <mjurczyk@...gle.com>,
        "David S . Miller" <davem@...emloft.net>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL for 3.18 028/101] caif: Add sockaddr length check
 before accessing sa_family in connect handler

From: Mateusz Jurczyk <mjurczyk@...gle.com>

[ Upstream commit 20a3d5bf5e5b13c02450ab6178ec374abd830686 ]

Verify that the caller-provided sockaddr structure is large enough to
contain the sa_family field, before accessing it in the connect()
handler of the AF_CAIF socket. Since the syscall doesn't enforce a minimum
size of the corresponding memory region, very short sockaddrs (zero or one
byte long) result in operating on uninitialized memory while referencing
sa_family.

Signed-off-by: Mateusz Jurczyk <mjurczyk@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 net/caif/caif_socket.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c
index 5e10ee0efffb..40389e5b8b32 100644
--- a/net/caif/caif_socket.c
+++ b/net/caif/caif_socket.c
@@ -758,6 +758,10 @@ static int caif_connect(struct socket *sock, struct sockaddr *uaddr,
 
 	lock_sock(sk);
 
+	err = -EINVAL;
+	if (addr_len < offsetofend(struct sockaddr, sa_family))
+		goto out;
+
 	err = -EAFNOSUPPORT;
 	if (uaddr->sa_family != AF_CAIF)
 		goto out;
-- 
2.15.1