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Date: Wed, 10 Jan 2018 18:02:59 -0800
From: Kees Cook <>
Cc: Kees Cook <>,
	David Windsor <>,
	Vlad Yasevich <>,
	Neil Horman <>,
	"David S. Miller" <>,,,
	Linus Torvalds <>,
	Alexander Viro <>,
	Andrew Morton <>,
	Andy Lutomirski <>,
	Christoph Hellwig <>,
	Christoph Lameter <>,
	Laura Abbott <>,
	Mark Rutland <>,
	"Martin K. Petersen" <>,
	Paolo Bonzini <>,
	Christian Borntraeger <>,
	Christoffer Dall <>,
	Dave Kleikamp <>,
	Jan Kara <>,
	Luis de Bethencourt <>,
	Marc Zyngier <>,
	Rik van Riel <>,
	Matthew Garrett <>,,,,
Subject: [PATCH 27/38] sctp: Copy struct sctp_sock.autoclose to userspace using put_user()

From: David Windsor <>

The autoclose field can be copied with put_user(), so there is no need to
use copy_to_user(). In both cases, hardened usercopy is being bypassed
since the size is constant, and not open to runtime manipulation.

This patch is verbatim from Brad Spengler/PaX Team's PAX_USERCOPY
whitelisting code in the last public patch of grsecurity/PaX based on my
understanding of the code. Changes or omissions from the original code are
mine and don't reflect the original grsecurity/PaX code.

Signed-off-by: David Windsor <>
[kees: adjust commit log]
Cc: Vlad Yasevich <>
Cc: Neil Horman <>
Cc: "David S. Miller" <>
Signed-off-by: Kees Cook <>
 net/sctp/socket.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index efbc8f52c531..15491491ec88 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -5011,7 +5011,7 @@ 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 (put_user(sctp_sk(sk)->autoclose, (int __user *)optval))
 		return -EFAULT;
 	return 0;

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