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author | Wentao Liang <Wentao_Liang_g@163.com> | 2022-04-07 05:51:59 -0400 |
---|---|---|
committer | Peter Maydell <peter.maydell@linaro.org> | 2022-04-08 15:02:09 +0100 |
commit | 4bf58c7213b0ab03209a53731c71f0861c35ef91 (patch) | |
tree | 4515001b9de1cf892fbf6155f9925103a0ffdc9f /hw/virtio | |
parent | dde8689d1fe82e295a278ba4bf1abd9be5c7bcab (diff) | |
download | qemu-4bf58c7213b0ab03209a53731c71f0861c35ef91.zip qemu-4bf58c7213b0ab03209a53731c71f0861c35ef91.tar.gz qemu-4bf58c7213b0ab03209a53731c71f0861c35ef91.tar.bz2 |
virtio-iommu: use-after-free fix
A potential Use-after-free was reported in virtio_iommu_handle_command
when using virtio-iommu:
> I find a potential Use-after-free in QEMU 6.2.0, which is in
> virtio_iommu_handle_command() (./hw/virtio/virtio-iommu.c).
>
>
> Specifically, in the loop body, the variable 'buf' allocated at line 639 can be
> freed by g_free() at line 659. However, if the execution path enters the loop
> body again and the if branch takes true at line 616, the control will directly
> jump to 'out' at line 651. At this time, 'buf' is a freed pointer, which is not
> assigned with an allocated memory but used at line 653. As a result, a UAF bug
> is triggered.
>
>
>
> 599 for (;;) {
> ...
> 615 sz = iov_to_buf(iov, iov_cnt, 0, &head, sizeof(head));
> 616 if (unlikely(sz != sizeof(head))) {
> 617 tail.status = VIRTIO_IOMMU_S_DEVERR;
> 618 goto out;
> 619 }
> ...
> 639 buf = g_malloc0(output_size);
> ...
> 651 out:
> 652 sz = iov_from_buf(elem->in_sg, elem->in_num, 0,
> 653 buf ? buf : &tail, output_size);
> ...
> 659 g_free(buf);
>
> We can fix it by set ‘buf‘ to NULL after freeing it:
>
>
> 651 out:
> 652 sz = iov_from_buf(elem->in_sg, elem->in_num, 0,
> 653 buf ? buf : &tail, output_size);
> ...
> 659 g_free(buf);
> +++ buf = NULL;
> 660 }
Fix as suggested by the reporter.
Signed-off-by: Wentao Liang <Wentao_Liang_g@163.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-id: 20220407095047.50371-1-mst@redhat.com
Message-ID: <20220406040445-mutt-send-email-mst@kernel.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'hw/virtio')
-rw-r--r-- | hw/virtio/virtio-iommu.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/hw/virtio/virtio-iommu.c b/hw/virtio/virtio-iommu.c index 664cbd9..6d5ea0b 100644 --- a/hw/virtio/virtio-iommu.c +++ b/hw/virtio/virtio-iommu.c @@ -683,6 +683,7 @@ out: virtio_notify(vdev, vq); g_free(elem); g_free(buf); + buf = NULL; } } |