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References: <20240411032155.208042-1-ytcoode@gmail.com>
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From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Thu, 11 Apr 2024 09:23:47 +0200
Message-ID: <CAMuHMdULF9KemeFkv09s3b9T8Ka-AkC8A8-pc_FpdXnjrOjwgQ@mail.gmail.com>
Subject: Re: [PATCH] init/main.c: Fix potential static_command_line memory overflow
To: Yuntao Wang <ytcoode@gmail.com>
Cc: linux-kernel@vger.kernel.org, Thomas Gleixner <tglx@linutronix.de>, 
	Andrew Morton <akpm@linux-foundation.org>, 
	"ndesaulniers@google.com" <ndesaulniers@google.com>, Josh Poimboeuf <jpoimboe@kernel.org>, 
	"Peter Zijlstra (Intel)" <peterz@infradead.org>, Tejun Heo <tj@kernel.org>, 
	Christophe Leroy <christophe.leroy@csgroup.eu>, Krister Johansen <kjlx@templeofstupid.com>, 
	Arnd Bergmann <arnd@arndb.de>, Mike Rapoport <rppt@kernel.org>, Masami Hiramatsu <mhiramat@kernel.org>
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CC Hiramatsu-san

On Thu, Apr 11, 2024 at 5:25=E2=80=AFAM Yuntao Wang <ytcoode@gmail.com> wro=
te:
> 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_lin=
e
> will overflow.
>
> Fixes: f5c7310ac73e ("init/main: add checks for the return value of membl=
ock_alloc*()")
> Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> ---
>  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 =3D strlen(extra_init_args) + 4; /* for " -- " */
>
> -       len =3D xlen + strlen(boot_command_line) + 1;
> +       len =3D xlen + strlen(boot_command_line) + ilen + 1;
>
> -       saved_command_line =3D memblock_alloc(len + ilen, SMP_CACHE_BYTES=
);
> +       saved_command_line =3D 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 =3D xlen + strlen(command_line) + 1;
>
>         static_command_line =3D memblock_alloc(len, SMP_CACHE_BYTES);
>         if (!static_command_line)

Gr{oetje,eeting}s,

                        Geert

--=20
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k=
org

In personal conversations with technical people, I call myself a hacker. Bu=
t
when I'm talking to journalists I just say "programmer" or something like t=
hat.
                                -- Linus Torvalds