Re: [PATCH] block/backup: fix memory leak in bdrv_backup_top_append()

[Eiichi Tsukata]

ping

On 2019/12/23 18:06, Eiichi Tsukata wrote:
> bdrv_open_driver() allocates bs->opaque according to drv->instance_size.
> There is no need to allocate it and overwrite opaque in
> bdrv_backup_top_append().
> 
> Reproducer:
> 
>   $ QTEST_QEMU_BINARY=./x86_64-softmmu/qemu-system-x86_64 valgrind -q 
> --leak-check=full tests/test-replication -p /replication/secondary/start
>   ==29792== 24 bytes in 1 blocks are definitely lost in loss record 52 of 226
>   ==29792==    at 0x483AB1A: calloc (vg_replace_malloc.c:762)
>   ==29792==    by 0x4B07CE0: g_malloc0 (in /usr/lib64/libglib-2.0.so.0.6000.7)
>   ==29792==    by 0x12BAB9: bdrv_open_driver (block.c:1289)
>   ==29792==    by 0x12BEA9: bdrv_new_open_driver (block.c:1359)
>   ==29792==    by 0x1D15CB: bdrv_backup_top_append (backup-top.c:190)
>   ==29792==    by 0x1CC11A: backup_job_create (backup.c:439)
>   ==29792==    by 0x1CD542: replication_start (replication.c:544)
>   ==29792==    by 0x1401B9: replication_start_all (replication.c:52)
>   ==29792==    by 0x128B50: test_secondary_start (test-replication.c:427)
>   ...
> 
> Fixes: 7df7868b9640 ("block: introduce backup-top filter driver")
> Signed-off-by: Eiichi Tsukata <address@hidden>
> ---
>  block/backup-top.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/block/backup-top.c b/block/backup-top.c
> index 7cdb1f8eba..617217374d 100644
> --- a/block/backup-top.c
> +++ b/block/backup-top.c
> @@ -196,7 +196,7 @@ BlockDriverState *bdrv_backup_top_append(BlockDriverState 
> *source,
>      }
>  
>      top->total_sectors = source->total_sectors;
> -    top->opaque = state = g_new0(BDRVBackupTopState, 1);
> +    state = top->opaque;
>  
>      bdrv_ref(target);
>      state->target = bdrv_attach_child(top, target, "target", &child_file, 
> errp);
>