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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>
CC:     Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
        "David S . Miller" <davem@davemloft.net>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.14 106/110] sctp: make use of pre-calculated len
Thread-Topic: [PATCH AUTOSEL for 4.14 106/110] sctp: make use of
 pre-calculated len
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Date:   Sat, 3 Feb 2018 18:01:34 +0000
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From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

[ Upstream commit c76f97c99ae6d26d14c7f0e50e074382bfbc9f98 ]

Some sockopt handling functions were calculating the length of the
buffer to be written to userspace and then calculating it again when
actually writing the buffer, which could lead to some write not using
an up-to-date length.

This patch updates such places to just make use of the len variable.

Also, replace some sizeof(type) to sizeof(var).

Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 net/sctp/socket.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 978fc7d1cf53..53e3634afea0 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4948,7 +4948,7 @@ static int sctp_getsockopt_autoclose(struct sock *sk,=
 int len, char __user *optv
 	len =3D sizeof(int);
 	if (put_user(len, optlen))
 		return -EFAULT;
-	if (copy_to_user(optval, &sctp_sk(sk)->autoclose, sizeof(int)))
+	if (copy_to_user(optval, &sctp_sk(sk)->autoclose, len))
 		return -EFAULT;
 	return 0;
 }
@@ -5579,6 +5579,9 @@ copy_getaddrs:
 		err =3D -EFAULT;
 		goto out;
 	}
+	/* XXX: We should have accounted for sizeof(struct sctp_getaddrs) too,
+	 * but we can't change it anymore.
+	 */
 	if (put_user(bytes_copied, optlen))
 		err =3D -EFAULT;
 out:
@@ -6015,7 +6018,7 @@ static int sctp_getsockopt_maxseg(struct sock *sk, in=
t len,
 		params.assoc_id =3D 0;
 	} else if (len >=3D sizeof(struct sctp_assoc_value)) {
 		len =3D sizeof(struct sctp_assoc_value);
-		if (copy_from_user(&params, optval, sizeof(params)))
+		if (copy_from_user(&params, optval, len))
 			return -EFAULT;
 	} else
 		return -EINVAL;
@@ -6185,7 +6188,9 @@ static int sctp_getsockopt_active_key(struct sock *sk=
, int len,
=20
 	if (len < sizeof(struct sctp_authkeyid))
 		return -EINVAL;
-	if (copy_from_user(&val, optval, sizeof(struct sctp_authkeyid)))
+
+	len =3D sizeof(struct sctp_authkeyid);
+	if (copy_from_user(&val, optval, len))
 		return -EFAULT;
=20
 	asoc =3D sctp_id2assoc(sk, val.scact_assoc_id);
@@ -6197,7 +6202,6 @@ static int sctp_getsockopt_active_key(struct sock *sk=
, int len,
 	else
 		val.scact_keynumber =3D ep->active_key_id;
=20
-	len =3D sizeof(struct sctp_authkeyid);
 	if (put_user(len, optlen))
 		return -EFAULT;
 	if (copy_to_user(optval, &val, len))
@@ -6223,7 +6227,7 @@ static int sctp_getsockopt_peer_auth_chunks(struct so=
ck *sk, int len,
 	if (len < sizeof(struct sctp_authchunks))
 		return -EINVAL;
=20
-	if (copy_from_user(&val, optval, sizeof(struct sctp_authchunks)))
+	if (copy_from_user(&val, optval, sizeof(val)))
 		return -EFAULT;
=20
 	to =3D p->gauth_chunks;
@@ -6268,7 +6272,7 @@ static int sctp_getsockopt_local_auth_chunks(struct s=
ock *sk, int len,
 	if (len < sizeof(struct sctp_authchunks))
 		return -EINVAL;
=20
-	if (copy_from_user(&val, optval, sizeof(struct sctp_authchunks)))
+	if (copy_from_user(&val, optval, sizeof(val)))
 		return -EFAULT;
=20
 	to =3D p->gauth_chunks;
--=20
2.11.0