qcow2: Assert that the crypto header does not overlap other metadata

The crypto header is initialized only when QEMU is creating a new
image, so there's no chance of this happening on a corrupted image.

If QEMU is really trying to allocate the header overlapping other
existing metadata sections then this is a serious bug in QEMU itself
so let's add an assertion.

Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-id: ae3d77f312fc0c5e0ac2bbd71676c0112eebe2e5.1509718618.git.berto@igalia.com
Reviewed-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

diff --git a/block/qcow2.c b/block/qcow2.c
index defc1fe49f51f1dad0d821b160ba48f1693331f9..b3d66a0e88c675c0ab971d5c6723a8e3672b3d47 100644 (file)
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -126,6 +126,7 @@ static ssize_t qcow2_crypto_hdr_init_func(QCryptoBlock *block, size_t headerlen,
     /* Zero fill remaining space in cluster so it has predictable
      * content in case of future spec changes */
     clusterlen = size_to_clusters(s, headerlen) * s->cluster_size;
+    assert(qcow2_pre_write_overlap_check(bs, 0, ret, clusterlen) == 0);
     ret = bdrv_pwrite_zeroes(bs->file,
                              ret + headerlen,
                              clusterlen - headerlen, 0);