55 lines
2.1 KiB
Diff
55 lines
2.1 KiB
Diff
From: yongduan <yongduan@tencent.com>
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Date: Wed, 11 Sep 2019 17:44:24 +0800
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Subject: vhost: make sure log_num < in_num
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Origin: https://git.kernel.org/linus/060423bfdee3f8bc6e2c1bac97de24d5415e2bc4
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Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-14835
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The code assumes log_num < in_num everywhere, and that is true as long as
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in_num is incremented by descriptor iov count, and log_num by 1. However
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this breaks if there's a zero sized descriptor.
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As a result, if a malicious guest creates a vring desc with desc.len = 0,
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it may cause the host kernel to crash by overflowing the log array. This
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bug can be triggered during the VM migration.
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There's no need to log when desc.len = 0, so just don't increment log_num
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in this case.
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Fixes: 3a4d5c94e959 ("vhost_net: a kernel-level virtio server")
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Cc: stable@vger.kernel.org
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Reviewed-by: Lidong Chen <lidongchen@tencent.com>
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Signed-off-by: ruippan <ruippan@tencent.com>
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Signed-off-by: yongduan <yongduan@tencent.com>
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Acked-by: Michael S. Tsirkin <mst@redhat.com>
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Reviewed-by: Tyler Hicks <tyhicks@canonical.com>
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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---
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drivers/vhost/vhost.c | 4 ++--
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1 file changed, 2 insertions(+), 2 deletions(-)
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diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
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index 34ea219936e3..acabf20b069e 100644
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--- a/drivers/vhost/vhost.c
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+++ b/drivers/vhost/vhost.c
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@@ -2180,7 +2180,7 @@ static int get_indirect(struct vhost_virtqueue *vq,
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/* If this is an input descriptor, increment that count. */
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if (access == VHOST_ACCESS_WO) {
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*in_num += ret;
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- if (unlikely(log)) {
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+ if (unlikely(log && ret)) {
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log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
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log[*log_num].len = vhost32_to_cpu(vq, desc.len);
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++*log_num;
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@@ -2321,7 +2321,7 @@ int vhost_get_vq_desc(struct vhost_virtqueue *vq,
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/* If this is an input descriptor,
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* increment that count. */
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*in_num += ret;
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- if (unlikely(log)) {
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+ if (unlikely(log && ret)) {
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log[*log_num].addr = vhost64_to_cpu(vq, desc.addr);
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log[*log_num].len = vhost32_to_cpu(vq, desc.len);
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++*log_num;
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--
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2.23.0
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