From b1eef66295a6c4f4f42b235592b339a8fa0d067c Mon Sep 17 00:00:00 2001
From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Date: Mon, 8 Jan 2018 19:02:29 -0200
Subject: [PATCH 5/7] sctp: make use of pre-calculated len
Git-commit: c76f97c99ae6d26d14c7f0e50e074382bfbc9f98
Patch-mainline: 4.15-rc8
References: git-fixes

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: Denis Kirjanov <denis.kirjanov@suse.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 4713dd8f5ecf..7e2914216f0f 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4983,7 +4983,7 @@ static int sctp_getsockopt_autoclose(struct sock *sk, int len, char __user *optv
 	len = 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;
 }
@@ -5560,6 +5560,9 @@ static int sctp_getsockopt_local_addrs(struct sock *sk, int len,
 		err = -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 = -EFAULT;
 out:
@@ -5996,7 +5999,7 @@ static int sctp_getsockopt_maxseg(struct sock *sk, int len,
 		params.assoc_id = 0;
 	} else if (len >= sizeof(struct sctp_assoc_value)) {
 		len = 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;
@@ -6165,7 +6168,9 @@ static int sctp_getsockopt_active_key(struct sock *sk, int len,
 
 	if (len < sizeof(struct sctp_authkeyid))
 		return -EINVAL;
-	if (copy_from_user(&val, optval, sizeof(struct sctp_authkeyid)))
+
+	len = sizeof(struct sctp_authkeyid);
+	if (copy_from_user(&val, optval, len))
 		return -EFAULT;
 
 	asoc = sctp_id2assoc(sk, val.scact_assoc_id);
@@ -6177,7 +6182,6 @@ static int sctp_getsockopt_active_key(struct sock *sk, int len,
 	else
 		val.scact_keynumber = ep->active_key_id;
 
-	len = sizeof(struct sctp_authkeyid);
 	if (put_user(len, optlen))
 		return -EFAULT;
 	if (copy_to_user(optval, &val, len))
@@ -6203,7 +6207,7 @@ static int sctp_getsockopt_peer_auth_chunks(struct sock *sk, int len,
 	if (len < sizeof(struct sctp_authchunks))
 		return -EINVAL;
 
-	if (copy_from_user(&val, optval, sizeof(struct sctp_authchunks)))
+	if (copy_from_user(&val, optval, sizeof(val)))
 		return -EFAULT;
 
 	to = p->gauth_chunks;
@@ -6248,7 +6252,7 @@ static int sctp_getsockopt_local_auth_chunks(struct sock *sk, int len,
 	if (len < sizeof(struct sctp_authchunks))
 		return -EINVAL;
 
-	if (copy_from_user(&val, optval, sizeof(struct sctp_authchunks)))
+	if (copy_from_user(&val, optval, sizeof(val)))
 		return -EFAULT;
 
 	to = p->gauth_chunks;
-- 
2.16.4