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From:   Huacai Chen <chenhc@lemote.com>
Date:   Tue, 13 Mar 2018 16:55:53 +0800
Message-ID: <CAAhV-H4zFAMjg9W2f1VfYrgLnDfNDPaUHUechGDT+v3o_8WNTg@mail.gmail.com>
Subject: Re: [PATCH V2] ZBOOT: fix stack protector in compressed boot phase
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
        Ralf Baechle <ralf@linux-mips.org>,
        James Hogan <james.hogan@mips.com>,
        Linux MIPS Mailing List <linux-mips@linux-mips.org>,
        Russell King <linux@arm.linux.org.uk>,
        linux-arm-kernel@lists.infradead.org,
        Yoshinori Sato <ysato@users.sourceforge.jp>,
        Rich Felker <dalias@libc.org>, linux-sh@vger.kernel.org,
        Huacai Chen <chenhc@lemote.com>,
        stable <stable@vger.kernel.org>
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Hi, Yoshinori, Rich and SuperH developers,

I'm not familiar with SuperH assembly, but SuperH has the same bug
obviously. Could you please fix that?

Huacai

On Mon, Mar 12, 2018 at 10:04 AM, Huacai Chen <chenhc@lemote.com> wrote:
> Call __stack_chk_guard_setup() in decompress_kernel() is too late that
> stack checking always fails for decompress_kernel() itself. So remove
> __stack_chk_guard_setup() and initialize __stack_chk_guard before we
> call decompress_kernel().
>
> Original code comes from ARM but also used for MIPS and SH, so fix them
> together. If without this fix, compressed booting of these archs will
> fail because stack checking is enabled by default (>=4.16).
>
> V2: Fix build on ARM.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Huacai Chen <chenhc@lemote.com>
> ---
>  arch/arm/boot/compressed/head.S        | 4 ++++
>  arch/arm/boot/compressed/misc.c        | 7 -------
>  arch/mips/boot/compressed/decompress.c | 7 -------
>  arch/mips/boot/compressed/head.S       | 4 ++++
>  arch/sh/boot/compressed/head_32.S      | 4 ++++
>  arch/sh/boot/compressed/head_64.S      | 4 ++++
>  arch/sh/boot/compressed/misc.c         | 7 -------
>  7 files changed, 16 insertions(+), 21 deletions(-)
>
> diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
> index 45c8823..bae1fc6 100644
> --- a/arch/arm/boot/compressed/head.S
> +++ b/arch/arm/boot/compressed/head.S
> @@ -547,6 +547,10 @@ not_relocated:     mov     r0, #0
>                 bic     r4, r4, #1
>                 blne    cache_on
>
> +               ldr     r0, =__stack_chk_guard
> +               ldr     r1, =0x000a0dff
> +               str     r1, [r0]
> +
>  /*
>   * The C runtime environment should now be setup sufficiently.
>   * Set up some pointers, and start decompressing.
> diff --git a/arch/arm/boot/compressed/misc.c b/arch/arm/boot/compressed/misc.c
> index 16a8a80..e518ef5 100644
> --- a/arch/arm/boot/compressed/misc.c
> +++ b/arch/arm/boot/compressed/misc.c
> @@ -130,11 +130,6 @@ asmlinkage void __div0(void)
>
>  unsigned long __stack_chk_guard;
>
> -void __stack_chk_guard_setup(void)
> -{
> -       __stack_chk_guard = 0x000a0dff;
> -}
> -
>  void __stack_chk_fail(void)
>  {
>         error("stack-protector: Kernel stack is corrupted\n");
> @@ -150,8 +145,6 @@ decompress_kernel(unsigned long output_start, unsigned long free_mem_ptr_p,
>  {
>         int ret;
>
> -       __stack_chk_guard_setup();
> -
>         output_data             = (unsigned char *)output_start;
>         free_mem_ptr            = free_mem_ptr_p;
>         free_mem_end_ptr        = free_mem_ptr_end_p;
> diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c
> index fdf99e9..5ba431c 100644
> --- a/arch/mips/boot/compressed/decompress.c
> +++ b/arch/mips/boot/compressed/decompress.c
> @@ -78,11 +78,6 @@ void error(char *x)
>
>  unsigned long __stack_chk_guard;
>
> -void __stack_chk_guard_setup(void)
> -{
> -       __stack_chk_guard = 0x000a0dff;
> -}
> -
>  void __stack_chk_fail(void)
>  {
>         error("stack-protector: Kernel stack is corrupted\n");
> @@ -92,8 +87,6 @@ void decompress_kernel(unsigned long boot_heap_start)
>  {
>         unsigned long zimage_start, zimage_size;
>
> -       __stack_chk_guard_setup();
> -
>         zimage_start = (unsigned long)(&__image_begin);
>         zimage_size = (unsigned long)(&__image_end) -
>             (unsigned long)(&__image_begin);
> diff --git a/arch/mips/boot/compressed/head.S b/arch/mips/boot/compressed/head.S
> index 409cb48..00d0ee0 100644
> --- a/arch/mips/boot/compressed/head.S
> +++ b/arch/mips/boot/compressed/head.S
> @@ -32,6 +32,10 @@ start:
>         bne     a2, a0, 1b
>          addiu  a0, a0, 4
>
> +       PTR_LA  a0, __stack_chk_guard
> +       PTR_LI  a1, 0x000a0dff
> +       sw      a1, 0(a0)
> +
>         PTR_LA  a0, (.heap)          /* heap address */
>         PTR_LA  sp, (.stack + 8192)  /* stack address */
>
> diff --git a/arch/sh/boot/compressed/head_32.S b/arch/sh/boot/compressed/head_32.S
> index 7bb1681..a3fdb05 100644
> --- a/arch/sh/boot/compressed/head_32.S
> +++ b/arch/sh/boot/compressed/head_32.S
> @@ -76,6 +76,10 @@ l1:
>         mov.l   init_stack_addr, r0
>         mov.l   @r0, r15
>
> +       mov.l   __stack_chk_guard, r0
> +       mov     #0x000a0dff, r1
> +       mov.l   r1, @r0
> +
>         /* Decompress the kernel */
>         mov.l   decompress_kernel_addr, r0
>         jsr     @r0
> diff --git a/arch/sh/boot/compressed/head_64.S b/arch/sh/boot/compressed/head_64.S
> index 9993113..8b4d540 100644
> --- a/arch/sh/boot/compressed/head_64.S
> +++ b/arch/sh/boot/compressed/head_64.S
> @@ -132,6 +132,10 @@ startup:
>         addi    r22, 4, r22
>         bne     r22, r23, tr1
>
> +       movi    datalabel __stack_chk_guard, r0
> +       movi    0x000a0dff, r1
> +       st.l    r0, 0, r1
> +
>         /*
>          * Decompress the kernel.
>          */
> diff --git a/arch/sh/boot/compressed/misc.c b/arch/sh/boot/compressed/misc.c
> index 627ce8e..fe4c079 100644
> --- a/arch/sh/boot/compressed/misc.c
> +++ b/arch/sh/boot/compressed/misc.c
> @@ -106,11 +106,6 @@ static void error(char *x)
>
>  unsigned long __stack_chk_guard;
>
> -void __stack_chk_guard_setup(void)
> -{
> -       __stack_chk_guard = 0x000a0dff;
> -}
> -
>  void __stack_chk_fail(void)
>  {
>         error("stack-protector: Kernel stack is corrupted\n");
> @@ -130,8 +125,6 @@ void decompress_kernel(void)
>  {
>         unsigned long output_addr;
>
> -       __stack_chk_guard_setup();
> -
>  #ifdef CONFIG_SUPERH64
>         output_addr = (CONFIG_MEMORY_START + 0x2000);
>  #else
> --
> 2.7.0
>