Re: [Qemu-devel] [PATCH] elf-ops.h: fix int overflow in load_elf()

[Peter Maydell]

On Tue, 10 Sep 2019 at 10:08, Stefano Garzarella <address@hidden> wrote:
>
> This patch fixes a possible integer overflow when we calculate
> the total size of ELF segments loaded.
>
> Reported-by: Coverity (CID 1405299)
> Signed-off-by: Stefano Garzarella <address@hidden>
> ---
> Now we are limited to INT_MAX, should load_elf() returns ssize_t
> to support bigger ELFs?
> ---
>  include/hw/elf_ops.h | 6 ++++++
>  hw/core/loader.c     | 1 +
>  2 files changed, 7 insertions(+)
>
> diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
> index 1496d7e753..46dd3bf413 100644
> --- a/include/hw/elf_ops.h
> +++ b/include/hw/elf_ops.h
> @@ -485,6 +485,12 @@ static int glue(load_elf, SZ)(const char *name, int fd,
>                  }
>              }
>
> +            if (mem_size > INT_MAX - total_size) {
> +                error_report("ELF total segments size is too big to load "
> +                             "max is %d)", INT_MAX);
> +                goto fail;
> +            }

This function doesn't report issues via error_report()
(some callers intentionally have fallback options for
what they try to do with the file), but by returning
a suitable error value in 'ret', so I think we should
continue that approach rather than adding an error_report()
call here.

I agree that accumulating the size in an 'int' is a bit
dubious these days.

thanks
-- PMM