Re: [Qemu-devel] [PATCH v2 06/20] dmg: Handle failure for potentially large allocations

[Benoît Canet]

The Wednesday 28 May 2014 à 16:37:39 (+0200), Kevin Wolf wrote :
> Some code in the block layer makes potentially huge allocations. Failure
> is not completely unexpected there, so avoid aborting qemu and handle
> out-of-memory situations gracefully.
> 
> This patch addresses the allocations in the dmg block driver.
> 
> Signed-off-by: Kevin Wolf <address@hidden>
> Reviewed-by: Stefan Hajnoczi <address@hidden>
> ---
>  block/dmg.c | 19 +++++++++++++------
>  1 file changed, 13 insertions(+), 6 deletions(-)
> 
> diff --git a/block/dmg.c b/block/dmg.c
> index 1e153cd..e455886 100644
> --- a/block/dmg.c
> +++ b/block/dmg.c
> @@ -284,8 +284,15 @@ static int dmg_open(BlockDriverState *bs, QDict 
> *options, int flags,
>      }
>  
>      /* initialize zlib engine */
> -    s->compressed_chunk = g_malloc(max_compressed_size + 1);
> -    s->uncompressed_chunk = g_malloc(512 * max_sectors_per_chunk);
> +    s->compressed_chunk = qemu_try_blockalign(bs->file,
> +                                              max_compressed_size + 1);
> +    s->uncompressed_chunk = qemu_try_blockalign(bs->file,
> +                                                512 * max_sectors_per_chunk);
> +    if (s->compressed_chunk == NULL || s->uncompressed_chunk == NULL) {
> +        ret = -ENOMEM;
> +        goto fail;
> +    }
> +
>      if (inflateInit(&s->zstream) != Z_OK) {
>          ret = -EINVAL;
>          goto fail;
> @@ -302,8 +309,8 @@ fail:
>      g_free(s->lengths);
>      g_free(s->sectors);
>      g_free(s->sectorcounts);
> -    g_free(s->compressed_chunk);
> -    g_free(s->uncompressed_chunk);
> +    qemu_vfree(s->compressed_chunk);
> +    qemu_vfree(s->uncompressed_chunk);
>      return ret;
>  }
>  
> @@ -426,8 +433,8 @@ static void dmg_close(BlockDriverState *bs)
>      g_free(s->lengths);
>      g_free(s->sectors);
>      g_free(s->sectorcounts);
> -    g_free(s->compressed_chunk);
> -    g_free(s->uncompressed_chunk);
> +    qemu_vfree(s->compressed_chunk);
> +    qemu_vfree(s->uncompressed_chunk);
>  
>      inflateEnd(&s->zstream);
>  }
> -- 
> 1.8.3.1
> 
> 
    Reviewed-by: Benoit Canet <address@hidden>