DivestOS/Patches/Linux_CVEs/CVE-2016-3775/3.10/0003.patch

From 8096090858689395a75bbf696ff8276c3c236b98 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@google.com>
Date: Thu, 25 Feb 2016 12:15:48 -0800
Subject: [PATCH] AIO: properly check iovec sizes

commit ff19ac8fb71e8a2bf07d61b959062998139c1104 upstream

In Linus's tree, the iovec code has been reworked massively, but in
older kernels the AIO layer should be checking this before passing the
request on to other layers.

Many thanks to Ben Hawkes of Google Project Zero for pointing out the
issue.

Bug: 28588279

Reported-by: Ben Hawkes <hawkes@google.com>
Acked-by: Benjamin LaHaise <bcrl@kvack.org>
Tested-by: Willy Tarreau <w@1wt.eu>
[backported to 3.10 - willy]
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

Change-Id: If539a08b42dd51a473b3f3743f9497e637266a05
---
 fs/aio.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index ded94c4fa30d3..9798d4edfd8f2 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -977,12 +977,17 @@ static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat)
 
 static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb)
 {
-	if (unlikely(!access_ok(!rw, kiocb->ki_buf, kiocb->ki_nbytes)))
-		return -EFAULT;
+	size_t len = kiocb->ki_nbytes;
+
+	if (len > MAX_RW_COUNT)
+		len = MAX_RW_COUNT;
+
+	if (unlikely(!access_ok(!rw, kiocb->ki_buf, len)))
+                return -EFAULT;
 
 	kiocb->ki_iovec = &kiocb->ki_inline_vec;
 	kiocb->ki_iovec->iov_base = kiocb->ki_buf;
-	kiocb->ki_iovec->iov_len = kiocb->ki_nbytes;
+	kiocb->ki_iovec->iov_len = len;
 	kiocb->ki_nr_segs = 1;
 	return 0;
 }