Re: [PATCH v2 2/2] hw/elf_ops: clear uninitialized segment space

[Stefano Garzarella]

On Thu, Apr 15, 2021 at 12:04:09PM +0200, Philippe Mathieu-Daudé wrote:
> From: Laurent Vivier <laurent@vivier.eu>
>
> When the mem_size of the segment is bigger than the file_size,
> and if this space doesn't overlap another segment, it needs
> to be cleared.
>
> This bug is very similar to the one we had for linux-user,
> 22d113b52f41 ("linux-user: Fix loading of BSS segments"),
> where .bss section is encoded as an extension of the the data
> one by setting the segment p_memsz > p_filesz.
>
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> Message-Id: <20210414105838.205019-1-laurent@vivier.eu>
> [PMD: Use recently added address_space_set()]
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
> include/hw/elf_ops.h | 13 +++++++++++++
> 1 file changed, 13 insertions(+)

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

> diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
> index 6ee458e7bc3..29f4c43e231 100644
> --- a/include/hw/elf_ops.h
> +++ b/include/hw/elf_ops.h
> @@ -562,6 +562,19 @@ static int glue(load_elf, SZ)(const char *name, int fd,
>                     if (res != MEMTX_OK) {
>                         goto fail;
>                     }
> +                    /*
> +                     * We need to zero'ify the space that is not copied
> +                     * from file
> +                     */
> +                    if (file_size < mem_size) {
> +                        res = address_space_set(as ? as : 
> &address_space_memory,
> +                                                addr + file_size, 0,
> +                                                mem_size - file_size,
> +                                                MEMTXATTRS_UNSPECIFIED);
> +                        if (res != MEMTX_OK) {
> +                            goto fail;
> +                        }
> +                    }
>                 }
>             }
>
> --
> 2.26.3