Am 14.11.2012 09:32, schrieb Stefan Hajnoczi:
> On Tue, Nov 13, 2012 at 03:14:55PM +0100, Kevin Wolf wrote:
>> @@ -691,12 +685,15 @@ static int bdrv_open_common(BlockDriverState *bs,
>> const char *filename,
>>
>> /* Open the image, either directly or using a protocol */
>> if (drv->bdrv_file_open) {
>> + if (file != NULL) {
>> + bdrv_swap(file, bs);
>> + bdrv_delete(file);
>> + }
>> ret = drv->bdrv_file_open(bs, filename, open_flags);
>> } else {
> [...]
>> /* Open the image */
>> - ret = bdrv_open_common(bs, filename, flags, drv);
>> + ret = bdrv_open_common(bs, file, filename, flags, drv);
>> if (ret < 0) {
>> goto unlink_and_fail;
>> }
>> @@ -894,6 +895,9 @@ int bdrv_open(BlockDriverState *bs, const char
>> *filename, int flags,
>> return 0;
>>
>> unlink_and_fail:
>> + if (file != NULL) {
>> + bdrv_delete(file);
>> + }
>
> Not sure I understand this code path.
>
> We have a protocol (the driver implements .bdrv_file_open()) so we swap
> file and bs, then delete old bs. Then we call .bdrv_file_open() on the
> already open file BDS.
>
> Is it okay to call .bdrv_file_open() on an already open BDS?
No, that looks buggy, even though in practice it doesn't explode at
least with raw-posix. It probably did leak a file descriptor.
> Now if .bdrv_file_open() fails we will bdrv_delete() the already deleted
> file BDS. This is a double-free.
I'll move the bdrv_delete up into bdrv_open (conditional on bs->file !=
file) and add a file = NULL after it, that should fix it.
Kevin
