linux-kernel - [PATCH AUTOSEL 4.19 11/18] xen/xenbus: ensure xenbus_map_ring

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200424122355.10453-11-sashal@kernel.org>
Date:   Fri, 24 Apr 2020 08:23:48 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Juergen Gross <jgross@...e.com>, Wei Liu <wl@....org>,
        Sasha Levin <sashal@...nel.org>, xen-devel@...ts.xenproject.org
Subject: [PATCH AUTOSEL 4.19 11/18] xen/xenbus: ensure xenbus_map_ring_valloc() returns proper grant status

From: Juergen Gross <jgross@...e.com>

[ Upstream commit 6b51fd3f65a22e3d1471b18a1d56247e246edd46 ]

xenbus_map_ring_valloc() maps a ring page and returns the status of the
used grant (0 meaning success).

There are Xen hypervisors which might return the value 1 for the status
of a failed grant mapping due to a bug. Some callers of
xenbus_map_ring_valloc() test for errors by testing the returned status
to be less than zero, resulting in no error detected and crashing later
due to a not available ring page.

Set the return value of xenbus_map_ring_valloc() to GNTST_general_error
in case the grant status reported by Xen is greater than zero.

This is part of XSA-316.

Signed-off-by: Juergen Gross <jgross@...e.com>
Reviewed-by: Wei Liu <wl@....org>
Link: https://lore.kernel.org/r/20200326080358.1018-1-jgross@suse.com
Signed-off-by: Juergen Gross <jgross@...e.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/xen/xenbus/xenbus_client.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/xen/xenbus/xenbus_client.c b/drivers/xen/xenbus/xenbus_client.c
index a1c17000129ba..e94a61eaeceb0 100644
--- a/drivers/xen/xenbus/xenbus_client.c
+++ b/drivers/xen/xenbus/xenbus_client.c
@@ -450,7 +450,14 @@ EXPORT_SYMBOL_GPL(xenbus_free_evtchn);
 int xenbus_map_ring_valloc(struct xenbus_device *dev, grant_ref_t *gnt_refs,
 			   unsigned int nr_grefs, void **vaddr)
 {
-	return ring_ops->map(dev, gnt_refs, nr_grefs, vaddr);
+	int err;
+
+	err = ring_ops->map(dev, gnt_refs, nr_grefs, vaddr);
+	/* Some hypervisors are buggy and can return 1. */
+	if (err > 0)
+		err = GNTST_general_error;
+
+	return err;
 }
 EXPORT_SYMBOL_GPL(xenbus_map_ring_valloc);
 
-- 
2.20.1