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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Lidong Chen <lidongchen@tencent.com>,
	ruippan <ruippan@tencent.com>, yongduan <yongduan@tencent.com>,
	"Michael S. Tsirkin" <mst@redhat.com>,
	Tyler Hicks <tyhicks@canonical.com>
Subject: [PATCH 4.9 14/14] vhost: make sure log_num < in_num
Date: Fri, 13 Sep 2019 14:07:07 +0100	[thread overview]
Message-ID: <20190913130446.949716002@linuxfoundation.org> (raw)
In-Reply-To: <20190913130440.264749443@linuxfoundation.org>

From: yongduan <yongduan@tencent.com>

commit 060423bfdee3f8bc6e2c1bac97de24d5415e2bc4 upstream.

The code assumes log_num < in_num everywhere, and that is true as long as
in_num is incremented by descriptor iov count, and log_num by 1. However
this breaks if there's a zero sized descriptor.

As a result, if a malicious guest creates a vring desc with desc.len = 0,
it may cause the host kernel to crash by overflowing the log array. This
bug can be triggered during the VM migration.

There's no need to log when desc.len = 0, so just don't increment log_num
in this case.

Fixes: 3a4d5c94e959 ("vhost_net: a kernel-level virtio server")
Cc: stable@vger.kernel.org
Reviewed-by: Lidong Chen <lidongchen@tencent.com>
Signed-off-by: ruippan <ruippan@tencent.com>
Signed-off-by: yongduan <yongduan@tencent.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/vhost/vhost.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1989,7 +1989,7 @@ static int get_indirect(struct vhost_vir
 		/* If this is an input descriptor, increment that count. */
 		if (access == VHOST_ACCESS_WO) {
 			*in_num += ret;
-			if (unlikely(log)) {
+			if (unlikely(log && ret)) {
 				log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
 				log[*log_num].len = vhost32_to_cpu(vq, desc.len);
 				++*log_num;
@@ -2125,7 +2125,7 @@ int vhost_get_vq_desc(struct vhost_virtq
 			/* If this is an input descriptor,
 			 * increment that count. */
 			*in_num += ret;
-			if (unlikely(log)) {
+			if (unlikely(log && ret)) {
 				log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
 				log[*log_num].len = vhost32_to_cpu(vq, desc.len);
 				++*log_num;



  parent reply	other threads:[~2019-09-13 13:09 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-13 13:06 [PATCH 4.9 00/14] 4.9.193-stable review Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.9 01/14] ALSA: hda - Fix potential endless loop at applying quirks Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.9 02/14] ALSA: hda/realtek - Fix overridden device-specific initialization Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.9 03/14] sched/fair: Dont assign runtime for throttled cfs_rq Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.9 04/14] drm/vmwgfx: Fix double free in vmw_recv_msg() Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.9 05/14] powerpc/tm: Fix FP/VMX unavailable exceptions inside a transaction Greg Kroah-Hartman
2019-09-13 13:06 ` [PATCH 4.9 06/14] xfrm: clean up xfrm protocol checks Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.9 07/14] ip6: fix skb leak in ip6frag_expire_frag_queue() Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.9 08/14] vhost/test: fix build for vhost test Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.9 09/14] batman-adv: fix uninit-value in batadv_netlink_get_ifindex() Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.9 10/14] batman-adv: Only read OGM tvlv_len after buffer len check Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.9 11/14] scripts/decode_stacktrace: match basepath using shell prefix operator, not regex Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.9 12/14] clk: s2mps11: Add used attribute to s2mps11_dt_match Greg Kroah-Hartman
2019-09-13 13:07 ` [PATCH 4.9 13/14] vhost: block speculation of translated descriptors Greg Kroah-Hartman
2019-09-13 13:07 ` Greg Kroah-Hartman [this message]
2019-09-13 20:19 ` [PATCH 4.9 00/14] 4.9.193-stable review kernelci.org bot
2019-09-14  3:58 ` Naresh Kamboju
2019-09-14  8:28 ` Guenter Roeck
2019-09-14  8:31   ` Greg Kroah-Hartman
2019-09-14  8:39     ` Guenter Roeck
2019-09-15  0:49     ` Guenter Roeck
2019-09-15 12:58       ` Greg Kroah-Hartman
2019-09-15 16:09         ` Guenter Roeck
2019-09-16  6:07           ` Greg Kroah-Hartman
2019-09-14  9:37   ` Christoph Biedl
2019-09-14 14:16 ` Guenter Roeck
2019-09-15 13:35 ` Greg Kroah-Hartman
2019-09-16 10:44   ` Naresh Kamboju
2019-09-16 10:45     ` Greg Kroah-Hartman
2019-09-16  9:17 ` Jon Hunter

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