On Fri, Jun 14, 2013 at 12:15 AM, Don Slutz <dsl...@verizon.com> wrote:
> On 06/12/13 03:08, Evgeny Budilovsky wrote:
>
>> The hard-coded 2k buffer on the stack won't allow reading big descriptor
>> files which can be generated when storing big images (For example 500G
>> vmdk splitted to 2G chunks).
>>
>> Signed-off-by: Evgeny Budilovsky
>> <evgeny.budilovsky@**ravellosystems.com<evgeny.budilov...@ravellosystems.com>
>> >
>> ---
>> block/vmdk.c | 28 +++++++++++++++++++++-------
>> 1 file changed, 21 insertions(+), 7 deletions(-)
>>
>> diff --git a/block/vmdk.c b/block/vmdk.c
>> index 608daaf..1bc944b 100644
>> --- a/block/vmdk.c
>> +++ b/block/vmdk.c
>> @@ -719,27 +719,41 @@ static int vmdk_open_desc_file(**BlockDriverState
>> *bs, int flags,
>> int64_t desc_offset)
>> {
>> int ret;
>> - char buf[2048];
>> + char *buf = NULL;
>> char ct[128];
>> BDRVVmdkState *s = bs->opaque;
>> + int64_t size;
>>
>> - ret = bdrv_pread(bs->file, desc_offset, buf, sizeof(buf));
>> + size = bdrv_get_allocated_file_size(**bs);
>> + if (size < 0) {
>> + return -EINVAL;
>> + }
>> +
>>
> While this is right for vmdk splitted to 2G chunks, I think this will fail
> for a big enough "monolithicFlat" vmdk where there is only the 1 file
> (g_malloc() will most likely fail for a 500GB file).
>
> With the "monolithicFlat" vmdk the descriptor file is a small textual
file. So this code should work. In the second version of this patch I've
added some constraint to the allocation size just in case the file is
corrupted or we have misinterpreted the format.
size = MIN(size, 1 << 20); /* avoid unbounded allocation */
buf = g_malloc0(size + 1);
+ buf = g_malloc0(size+1);
>> +
>> + ret = bdrv_pread(bs->file, desc_offset, buf, size);
>> if (ret < 0) {
>> - return ret;
>> + goto exit;
>> }
>> - buf[2047] = '\0';
>> if (vmdk_parse_description(buf, "createType", ct, sizeof(ct))) {
>> - return -EMEDIUMTYPE;
>> + ret = -EMEDIUMTYPE;
>> + goto exit;
>> }
>> if (strcmp(ct, "monolithicFlat") &&
>> strcmp(ct, "twoGbMaxExtentSparse") &&
>> strcmp(ct, "twoGbMaxExtentFlat")) {
>> fprintf(stderr,
>> "VMDK: Not supported image type \"%s\""".\n", ct);
>> - return -ENOTSUP;
>> + ret = -ENOTSUP;
>> + goto exit;
>> }
>> s->desc_offset = 0;
>> - return vmdk_parse_extents(buf, bs, bs->file->filename);
>> + ret = vmdk_parse_extents(buf, bs, bs->file->filename);
>> +exit:
>> + if (buf) {
>> + g_free(buf);
>> + }
>> + return ret;
>> }
>>
>> static int vmdk_open(BlockDriverState *bs, QDict *options, int flags)
>> --
>> 1.7.9.5
>>
>> -Don Slutz
>
--
Best Regards,
Evgeny
