NAK: [J][PATCH 1/2] s390/kexec_file: move kernel image size check

[Krzysztof Kozlowski]

On 17/02/2022 09:30, frank.heimes at canonical.com wrote:
> From: Sven Schnelle <svens at linux.ibm.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1959984
> 
> In preparation of adding support for command lines with variable
> sizes on s390, the check whether the new kernel image is at least HEAD_END
> bytes long isn't correct. Move the check to kexec_file_add_components()
> so we can get the size of the parm area and check the size there.
> 
> The '.org HEAD_END' directive can now also be removed from head.S. This
> was used in the past to reserve space for the early sccb buffer, but with
> commit 9a5131b87cac1 ("s390/boot: move sclp early buffer from fixed address
> in asm to C") this is no longer required.
> 
> Signed-off-by: Sven Schnelle <svens at linux.ibm.com>
> Reviewed-by: Heiko Carstens <hca at linux.ibm.com>
> Signed-off-by: Vasily Gorbik <gor at linux.ibm.com>
> (cherry picked from commit 277c8389386e2ccb8417afe4e36f67fc5dcd735d)
> Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
> ---
>  arch/s390/boot/head.S                 |  2 --
>  arch/s390/include/asm/setup.h         |  1 -
>  arch/s390/kernel/machine_kexec_file.c | 25 ++-----------------------
>  3 files changed, 2 insertions(+), 26 deletions(-)
> 
> diff --git a/arch/s390/boot/head.S b/arch/s390/boot/head.S
> index 40f4cff538b8..f3a8dba7dd5d 100644
> --- a/arch/s390/boot/head.S
> +++ b/arch/s390/boot/head.S
> @@ -383,5 +383,3 @@ SYM_DATA_START(parmarea)
>  	.byte	0
>  	.org	PARMAREA+__PARMAREA_SIZE
>  SYM_DATA_END(parmarea)
> -
> -	.org	HEAD_END
> diff --git a/arch/s390/include/asm/setup.h b/arch/s390/include/asm/setup.h
> index b6606ffd85d8..121e1a8c41d7 100644
> --- a/arch/s390/include/asm/setup.h
> +++ b/arch/s390/include/asm/setup.h
> @@ -11,7 +11,6 @@
>  #include <linux/build_bug.h>
>  
>  #define PARMAREA		0x10400
> -#define HEAD_END		0x11000
>  
>  /*
>   * Machine features detected in early.c
> diff --git a/arch/s390/kernel/machine_kexec_file.c b/arch/s390/kernel/machine_kexec_file.c
> index a81d6c43b9b6..6944d9abee1e 100644
> --- a/arch/s390/kernel/machine_kexec_file.c
> +++ b/arch/s390/kernel/machine_kexec_file.c
> @@ -235,7 +235,8 @@ void *kexec_file_add_components(struct kimage *image,
>  	if (ret)
>  		goto out;
>  
> -	if (image->cmdline_buf_len >= ARCH_COMMAND_LINE_SIZE) {
> +	if (image->kernel_buf_len < PARMAREA + sizeof(struct parmarea) ||
> +	    image->cmdline_buf_len >= ARCH_COMMAND_LINE_SIZE) {
>  		ret = -EINVAL;
>  		goto out;
>  	}
> @@ -324,25 +325,3 @@ int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
>  	}
>  	return 0;
>  }
> -
> -int arch_kexec_kernel_image_probe(struct kimage *image, void *buf,
> -				  unsigned long buf_len)
> -{
> -	/* A kernel must be at least large enough to contain head.S. During
> -	 * load memory in head.S will be accessed, e.g. to register the next
> -	 * command line. If the next kernel were smaller the current kernel
> -	 * will panic at load.
> -	 */
> -	if (buf_len < HEAD_END)
> -		return -ENOEXEC;
> -
> -	return kexec_image_probe_default(image, buf, buf_len);
> -}
> -
> -int arch_kimage_file_post_load_cleanup(struct kimage *image)
> -{

This should stay. It was not part of original commit.

> -	vfree(image->arch.ipl_buf);
> -	image->arch.ipl_buf = NULL;
> -
> -	return kexec_image_post_load_cleanup_default(image);
> -}


Best regards,
Krzysztof