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virtio-balloon: Corrections to address verification 

The virtio-balloon device's verification of the address given to it by the
guest has a number of faults:
    * The addresses here are guest physical addresses, which should be
      'hwaddr' rather than 'ram_addr_t' (the distinction is admittedly
      pretty subtle and confusing)
    * We don't check for section.mr being NULL, which is the main way that
      memory_region_find() reports basic failures.  We really need to check
      that before looking at any other section fields, because
      memory_region_find() doesn't initialize them on the failure path
    * We're passing a length of '1' to memory_region_find(), but really the
      guest is requesting that we put the entire page into the balloon,
      so it makes more sense to call it with BALLOON_PAGE_SIZE

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20190214043916.22128-3-david@gibson.dropbear.id.au>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This commit is contained in:
David Gibson 2019-02-14 15:39:13 +11:00 committed by Michael S. Tsirkin
parent f6deb6d95a
commit b218a70e6a
1 changed files with 10 additions and 7 deletions
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17
hw/virtio/virtio-balloon.c
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@ -221,17 +221,20 @@ static void virtio_balloon_handle_output(VirtIODevice *vdev, VirtQueue *vq)
}
while (iov_to_buf(elem->out_sg, elem->out_num, offset, &pfn, 4) == 4) {
ram_addr_t pa;
ram_addr_t addr;
hwaddr pa;
hwaddr addr;
int p = virtio_ldl_p(vdev, &pfn);
pa = (ram_addr_t) p << VIRTIO_BALLOON_PFN_SHIFT;
pa = (hwaddr) p << VIRTIO_BALLOON_PFN_SHIFT;
offset += 4;
/* FIXME: remove get_system_memory(), but how? */
section = memory_region_find(get_system_memory(), pa, 1);
if (!int128_nz(section.size) ||
!memory_region_is_ram(section.mr) ||
section = memory_region_find(get_system_memory(), pa,
BALLOON_PAGE_SIZE);
if (!section.mr) {
trace_virtio_balloon_bad_addr(pa);
continue;
}
if (!memory_region_is_ram(section.mr) ||
memory_region_is_rom(section.mr) ||
memory_region_is_romd(section.mr)) {
trace_virtio_balloon_bad_addr(pa);