diff options
| author | yongduan <yongduan@tencent.com> | 2019-09-11 17:44:24 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-09-16 08:13:36 +0200 |
| commit | 35b29a78cc9b2523f6b0c080e6b44d2eeb367023 (patch) | |
| tree | 0885f335b82ee01532bb5c4117f7149fa539bbd2 | |
| parent | 8cc953562e2e293575514c40806eee438a967364 (diff) | |
vhost: make sure log_num < in_num
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>
| -rw-r--r-- | drivers/vhost/vhost.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 0f653f314876..eb7a4df69e2b 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1324,7 +1324,7 @@ static int get_indirect(struct vhost_virtqueue *vq, /* If this is an input descriptor, increment that count. */ if (desc.flags & cpu_to_vhost16(vq, VRING_DESC_F_WRITE)) { *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; @@ -1453,7 +1453,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq, /* 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; |