3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marcelo Ricardo Leitner <marcelo.leit...@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.leit...@gmail.com>
Signed-off-by: David S. Miller <da...@davemloft.net>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 net/sctp/socket.c |   16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4458,7 +4458,7 @@ static int sctp_getsockopt_autoclose(str
        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;
 }
@@ -5035,6 +5035,9 @@ copy_getaddrs:
                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:
@@ -5471,7 +5474,7 @@ static int sctp_getsockopt_maxseg(struct
                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;
@@ -5635,7 +5638,9 @@ static int sctp_getsockopt_active_key(st
 
        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);
@@ -5647,7 +5652,6 @@ static int sctp_getsockopt_active_key(st
        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))
@@ -5673,7 +5677,7 @@ static int sctp_getsockopt_peer_auth_chu
        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;
@@ -5718,7 +5722,7 @@ static int sctp_getsockopt_local_auth_ch
        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;


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