Re: [Qemu-devel] [PATCH 1/4] load_image_targphys() should enforce the max size

[Stefan Weil <sw@weilnetz.de>]

Am 11.01.2012 06:44, schrieb David Gibson:
> From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>
> load_image_targphys() gets passed a max size for the file, but
> doesn't enforce it at all. Add a check and return -1 (error) if
> the file is too big, without loading it.
>
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
> ---
> hw/loader.c | 2 ++
> 1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/hw/loader.c b/hw/loader.c
> index 446b628..7ad9e22 100644
> --- a/hw/loader.c
> +++ b/hw/loader.c
> @@ -108,6 +108,8 @@ int load_image_targphys(const char *filename,
> int size;
>
> size = get_image_size(filename);
> + if (size > max_sz)
> + return -1;
> if (size > 0)
> rom_add_file_fixed(filename, addr, -1);
> return size;

Even if this file is full of block statements without braces,
we should not add more of them. See CODING_STYLE and
scripts/checkpatch.pl.

There remains an additional problem:
Using 'int' for the size of files was sufficient 10 years ago,
but it is that no longer. get_image_size() silently reduced the
return value from lseek() to an 'int' value. So even with your
patch, very large files will be loaded (partially)!

Regards,
Stefan Weil