[v2] virtio, pc: fixes, features

[PULL v2 30/30] Fixed assert in vhost_user_set_mem_table_postcopy

Michael S. Tsirkin posted 30 patches 5 years, 8 months ago

Diff against v1 v1 v1 v2 v3
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Maintainers: Max Reitz <mreitz@redhat.com>, Igor Mammedov <imammedo@redhat.com>, Eduardo Habkost <ehabkost@redhat.com>, "Gonglei (Arei)" <arei.gonglei@huawei.com>, Gerd Hoffmann <kraxel@redhat.com>, Stefan Hajnoczi <stefanha@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Kevin Wolf <kwolf@redhat.com>, Paolo Bonzini <pbonzini@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, "Daniel P. Berrangé" <berrange@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, Thomas Huth <thuth@redhat.com>, "Dr. David Alan Gilbert" <dgilbert@redhat.com>, Laurent Vivier <lvivier@redhat.com>

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[PULL v2 30/30] Fixed assert in vhost_user_set_mem_table_postcopy

Posted by Michael S. Tsirkin 5 years, 8 months ago

From: Raphael Norwitz <raphael.norwitz@nutanix.com>

The current vhost_user_set_mem_table_postcopy() implementation
populates each region of the VHOST_USER_SET_MEM_TABLE message without
first checking if there are more than VHOST_MEMORY_MAX_NREGIONS already
populated. This can cause memory corruption if too many regions are
added to the message during the postcopy step.

This change moves an existing assert up such that attempting to
construct a VHOST_USER_SET_MEM_TABLE message with too many memory
regions will gracefully bring down qemu instead of corrupting memory.

Signed-off-by: Raphael Norwitz <raphael.norwitz@nutanix.com>
Signed-off-by: Peter Turschmid <peter.turschm@nutanix.com>
Message-Id: <1579143426-18305-2-git-send-email-raphael.norwitz@nutanix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 hw/virtio/vhost-user.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 35baf4f347..08e7e63790 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -443,6 +443,7 @@ static int vhost_user_set_mem_table_postcopy(struct vhost_dev *dev,
                                      &offset);
         fd = memory_region_get_fd(mr);
         if (fd > 0) {
+            assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
             trace_vhost_user_set_mem_table_withfd(fd_num, mr->name,
                                                   reg->memory_size,
                                                   reg->guest_phys_addr,
@@ -455,7 +456,6 @@ static int vhost_user_set_mem_table_postcopy(struct vhost_dev *dev,
             msg.payload.memory.regions[fd_num].guest_phys_addr =
                 reg->guest_phys_addr;
             msg.payload.memory.regions[fd_num].mmap_offset = offset;
-            assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
             fds[fd_num++] = fd;
         } else {
             u->region_rb_offset[i] = 0;
-- 
MST