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

[Tim Gardner]

On 2/17/22 1:47 AM, Krzysztof Kozlowski wrote:
> 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)

This is a backport.

>> 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
> 

-- 
-----------
Tim Gardner
Canonical, Inc