aboutsummaryrefslogtreecommitdiff
path: root/hw/virtio/virtio-iommu.c
diff options
context:
space:
mode:
authorWentao Liang <Wentao_Liang_g@163.com>2022-04-07 05:51:59 -0400
committerPeter Maydell <peter.maydell@linaro.org>2022-04-08 15:02:09 +0100
commit4bf58c7213b0ab03209a53731c71f0861c35ef91 (patch)
tree4515001b9de1cf892fbf6155f9925103a0ffdc9f /hw/virtio/virtio-iommu.c
parentdde8689d1fe82e295a278ba4bf1abd9be5c7bcab (diff)
downloadqemu-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/virtio-iommu.c')
-rw-r--r--hw/virtio/virtio-iommu.c1
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;
}
}