Karmic, Lucid, Maverick: SRU: CVE-2010-3865

Stefan Bader stefan.bader at canonical.com
Fri Jan 28 14:36:49 UTC 2011

Code has changed reasonable since Maverick but same patch applies to
all older affected releases.

>From 2a8309b4f615072025743fae22147be5aa8e86cd Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds at linux-foundation.org>
Date: Thu, 28 Oct 2010 15:40:55 +0000
Subject: [PATCH] net: fix rds_iovec page count overflow

BugLink: http://bugs.launchpad.net/bugs/709153

As reported by Thomas Pollet, the rdma page counting can overflow.  We
get the rdma sizes in 64-bit unsigned entities, but then limit it to
UINT_MAX bytes and shift them down to pages (so with a possible "+1" for
an unaligned address).

So each individual page count fits comfortably in an 'unsigned int' (not
even close to overflowing into signed), but as they are added up, they
might end up resulting in a signed return value. Which would be wrong.

Catch the case of tot_pages turning negative, and return the appropriate
error code.

Reported-by: Thomas Pollet <thomas.pollet at gmail.com>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
Signed-off-by: Andy Grover <andy.grover at oracle.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
(backported from commit 1b1f693d7ad6d193862dcb1118540a030c5e761f upstream)
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
 net/rds/rdma.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)

diff --git a/net/rds/rdma.c b/net/rds/rdma.c
index 3998967..0a403a7 100644
--- a/net/rds/rdma.c
+++ b/net/rds/rdma.c
@@ -500,6 +500,16 @@ static struct rds_rdma_op *rds_rdma_prepare(struct rds_sock *rs,
 		max_pages = max(nr, max_pages);
 		nr_pages += nr;
+		/*
+		 * nr for one entry in limited to (UINT_MAX>>PAGE_SHIFT)+1
+		 * so nr_pages cannot overflow without first going negative.
+		 * If nr cannot overflow then max_pages should be ok.
+		 */
+		if (nr_pages < 0) {
+			ret = -EINVAL;
+			goto out;
+		}
 	pages = kcalloc(max_pages, sizeof(struct page *), GFP_KERNEL);

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