Re: [PATCH] init/main.c: Fix potential static_command_line memory overflow

[Geert Uytterhoeven]

CC Hiramatsu-san

On Thu, Apr 11, 2024 at 5:25 AM Yuntao Wang <ytcoode@xxxxxxxxx> wrote:
> We allocate memory of size 'xlen + strlen(boot_command_line) + 1' for
> static_command_line, but the strings copied into static_command_line are
> extra_command_line and command_line, rather than extra_command_line and
> boot_command_line.
>
> When strlen(command_line) > strlen(boot_command_line), static_command_line
> will overflow.
>
> Fixes: f5c7310ac73e ("init/main: add checks for the return value of memblock_alloc*()")
> Signed-off-by: Yuntao Wang <ytcoode@xxxxxxxxx>
> ---
>  init/main.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/init/main.c b/init/main.c
> index 2ca52474d0c3..a7b1f5f3e3b6 100644
> --- a/init/main.c
> +++ b/init/main.c
> @@ -625,11 +625,13 @@ static void __init setup_command_line(char *command_line)
>         if (extra_init_args)
>                 ilen = strlen(extra_init_args) + 4; /* for " -- " */
>
> -       len = xlen + strlen(boot_command_line) + 1;
> +       len = xlen + strlen(boot_command_line) + ilen + 1;
>
> -       saved_command_line = memblock_alloc(len + ilen, SMP_CACHE_BYTES);
> +       saved_command_line = memblock_alloc(len, SMP_CACHE_BYTES);
>         if (!saved_command_line)
> -               panic("%s: Failed to allocate %zu bytes\n", __func__, len + ilen);
> +               panic("%s: Failed to allocate %zu bytes\n", __func__, len);
> +
> +       len = xlen + strlen(command_line) + 1;
>
>         static_command_line = memblock_alloc(len, SMP_CACHE_BYTES);
>         if (!static_command_line)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68korg

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds