On 09/15/2014 04:22 PM, Peter Krempa wrote:
The backing store string location offset 0 determines that the file isn't present. The string size shouldn't be then checked:
from qemu.git/docs/specs/qcow2.txt
== Header ==
The first cluster of a qcow2 image contains the file header:
Byte 0 - 3: magic QCOW magic string ("QFI\xfb")
4 - 7: version Version number (valid values are 2 and 3)
8 - 15: backing_file_offset Offset into the image file at which the backing file name is stored (NB: The string is not null terminated). 0 if the image doesn't have a backing file.
16 - 19: backing_file_size Length of the backing file name in bytes. Must not be longer than 1023 bytes. Undefined if the image doesn't have a backing file. ^^^^^^^^^
This patch intentionally leaves the backing file string size check in place in case a malformatted file would be presented to libvirt. Also according to the docs the string size is maximum 1023 bytes, thus this patch adds a check to verify that.
I was also able to verify that the check was done the same way in the legacy qcow fromat (in qemu's code). --- src/util/virstoragefile.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
ACK Jan