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| author |   yongduan <yongduan@tencent.com> | 2019-09-11 17:44:24 +0800 |
|---|---|---|
| committer |   Michael S. Tsirkin <mst@redhat.com> | 2019-09-11 15:15:26 -0400 |
| commit | 060423bfdee3f8bc6e2c1bac97de24d5415e2bc4 (patch) | |
| tree | 1d29fdf287bcd13ee916712b2d31ac2cd6ad449d /drivers/vhost/vhost.c | |
| parent | vhost: block speculation of translated descriptors (diff) | |
| download | linux-dev-060423bfdee3f8bc6e2c1bac97de24d5415e2bc4.tar.xz linux-dev-060423bfdee3f8bc6e2c1bac97de24d5415e2bc4.zip | |
vhost: make sure log_num < in_num
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>
Diffstat (limited to 'drivers/vhost/vhost.c')
| -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 34ea219936e3..acabf20b069e 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -2180,7 +2180,7 @@ static int get_indirect(struct vhost_virtqueue *vq, /* 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; @@ -2321,7 +2321,7 @@ 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; |