Karmic CVE: bio: take care not overflow page count when mapping/copying user data, CVE-2010-4162

[Tim Gardner]

The following changes since commit 41866a96c222c7d5d3da3abffb166ff3b80e1f3b:
  Steve Conklin (1):
        UBUNTU: Ubuntu-2.6.31-22.73

are available in the git repository at:

  git://kernel.ubuntu.com/rtg/ubuntu-karmic.git CVE-2010-4162

Jens Axboe (1):
      bio: take care not overflow page count when mapping/copying user data, CVE-2010-4162

 fs/bio.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

>From ace13f458e62d5ed3722e61e4fc0c39ca90ddf15 Mon Sep 17 00:00:00 2001
From: Jens Axboe <jaxboe at fusionio.com>
Date: Wed, 10 Nov 2010 14:36:25 +0100
Subject: [PATCH] bio: take care not overflow page count when mapping/copying user data, CVE-2010-4162

BugLink: http://bugs.launchpad.net/bugs/721441

CVE-2010-4162

commit cb4644cac4a2797afc847e6c92736664d4b0ea34 upstream.

If the iovec is being set up in a way that causes uaddr + PAGE_SIZE
to overflow, we could end up attempting to map a huge number of
pages. Check for this invalid input type.

Reported-by: Dan Rosenberg <drosenberg at vsecurity.com>
Signed-off-by: Jens Axboe <jaxboe at fusionio.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at suse.de>
Signed-off-by: Tim Gardner <tim.gardner at canonical.com>
---
 fs/bio.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)

diff --git a/fs/bio.c b/fs/bio.c
index 7673800..8bcc085 100644
--- a/fs/bio.c
+++ b/fs/bio.c
@@ -813,6 +813,12 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
 		end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 		start = uaddr >> PAGE_SHIFT;
 
+		/*
+		 * Overflow, abort
+		 */
+		if (end < start)
+			return ERR_PTR(-EINVAL);
+
 		nr_pages += end - start;
 		len += iov[i].iov_len;
 	}
@@ -939,6 +945,12 @@ static struct bio *__bio_map_user_iov(struct request_queue *q,
 		unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
 		unsigned long start = uaddr >> PAGE_SHIFT;
 
+		/*
+		 * Overflow, abort
+		 */
+		if (end < start)
+			return ERR_PTR(-EINVAL);
+
 		nr_pages += end - start;
 		/*
 		 * buffer must be aligned to at least hardsector size for now
@@ -966,7 +978,7 @@ static struct bio *__bio_map_user_iov(struct request_queue *q,
 		unsigned long start = uaddr >> PAGE_SHIFT;
 		const int local_nr_pages = end - start;
 		const int page_limit = cur_page + local_nr_pages;
-		
+
 		ret = get_user_pages_fast(uaddr, local_nr_pages,
 				write_to_vm, &pages[cur_page]);
 		if (ret < local_nr_pages) {
-- 
1.7.0.4