Re: [PATCH] kexec: return -ENOEXEC from image probe functions on mismatch

[Mukesh Pilaniya <mpilaniy@redhat.com>]

Hi Philipp,

On 13/08/26 6:43 pm, Philipp Rudo wrote:
> Hi Mukesh,
> 
> the patch looks good to me.
> 
> There is also a corresponding kexec-tools patch, which was accidentally
> opened as a Github PR (https://github.com/horms/kexec-tools/pull/12).
> It will be sent to kexec@lists.infradead.org shortly.
> 
> Thanks
> 
> Reviewed-by: Philipp Rudo <prudo@redhat.com>
> 
The kexec-tools patch has now been posted to the mailing list.
It can be found here:
https://lore.kernel.org/all/20260814075329.30203-1-mpilaniy@redhat.com/

> On Thu, 13 Aug 2026 12:36:29 +0530
> Mukesh Pilaniya <mpilaniy@redhat.com> wrote:
> 
>> Several kexec_file_load() image probe functions return -EINVAL when
>> they do not recognize the image format.  A probe function that rejects
>> an image should return -ENOEXEC to indicate that the image is not a
>> recognized executable format.  -EINVAL implies a problem with the
>> syscall parameters, not with image recognition.
>>
>> kexec_image_probe_default() iterates through registered loaders and
>> returns the last probe's error code to the caller.  That error
>> propagates as the kexec_file_load() return value to userspace.
>> Returning -EINVAL from a probe when no loader matches is semantically
>> incorrect and misleads userspace about the nature of the failure.
>>
>> Return -ENOEXEC from all probe functions and their helpers when the
>> image format is not recognized.
>>
>> Signed-off-by: Mukesh Pilaniya <mpilaniy@redhat.com>
>> ---
>> branch: next-20260812
>> base commit: 28d012efb4327f9c75d5e042a7c91e9a542efa98
>> ---
>>   arch/arm64/kernel/kexec_image.c   | 4 ++--
>>   arch/loongarch/kernel/kexec_efi.c | 4 ++--
>>   arch/riscv/kernel/kexec_image.c   | 4 ++--
>>   kernel/kexec_elf.c                | 4 ++--
>>   4 files changed, 8 insertions(+), 8 deletions(-)
>>
>> diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
>> index b70f4df15a1a..101259874d44 100644
>> --- a/arch/arm64/kernel/kexec_image.c
>> +++ b/arch/arm64/kernel/kexec_image.c
>> @@ -25,10 +25,10 @@ static int image_probe(const char *kernel_buf, unsigned long kernel_len)
>>   		(const struct arm64_image_header *)(kernel_buf);
>>   
>>   	if (!h || (kernel_len < sizeof(*h)))
>> -		return -EINVAL;
>> +		return -ENOEXEC;
>>   
>>   	if (memcmp(&h->magic, ARM64_IMAGE_MAGIC, sizeof(h->magic)))
>> -		return -EINVAL;
>> +		return -ENOEXEC;
>>   
>>   	return 0;
>>   }
>> diff --git a/arch/loongarch/kernel/kexec_efi.c b/arch/loongarch/kernel/kexec_efi.c
>> index 5ee78ebb1546..28a1d0420ba3 100644
>> --- a/arch/loongarch/kernel/kexec_efi.c
>> +++ b/arch/loongarch/kernel/kexec_efi.c
>> @@ -24,12 +24,12 @@ static int efi_kexec_probe(const char *kernel_buf, unsigned long kernel_len)
>>   
>>   	if (!h || (kernel_len < sizeof(*h))) {
>>   		kexec_dprintk("No LoongArch image header.\n");
>> -		return -EINVAL;
>> +		return -ENOEXEC;
>>   	}
>>   
>>   	if (!loongarch_header_check_dos_sig(h)) {
>>   		kexec_dprintk("No LoongArch PE image header.\n");
>> -		return -EINVAL;
>> +		return -ENOEXEC;
>>   	}
>>   
>>   	return 0;
>> diff --git a/arch/riscv/kernel/kexec_image.c b/arch/riscv/kernel/kexec_image.c
>> index 51dc89259f16..963a25f5b55b 100644
>> --- a/arch/riscv/kernel/kexec_image.c
>> +++ b/arch/riscv/kernel/kexec_image.c
>> @@ -20,7 +20,7 @@ static int image_probe(const char *kernel_buf, unsigned long kernel_len)
>>   	const struct riscv_image_header *h = (const struct riscv_image_header *)kernel_buf;
>>   
>>   	if (!h || kernel_len < sizeof(*h))
>> -		return -EINVAL;
>> +		return -ENOEXEC;
>>   
>>   	/* According to Documentation/arch/riscv/boot-image-header.rst,
>>   	 * use "magic2" field to check when version >= 0.2.
>> @@ -28,7 +28,7 @@ static int image_probe(const char *kernel_buf, unsigned long kernel_len)
>>   
>>   	if (h->version >= RISCV_HEADER_VERSION &&
>>   	    memcmp(&h->magic2, RISCV_IMAGE_MAGIC2, sizeof(h->magic2)))
>> -		return -EINVAL;
>> +		return -ENOEXEC;
>>   
>>   	return 0;
>>   }
>> diff --git a/kernel/kexec_elf.c b/kernel/kexec_elf.c
>> index 3a5c25b2adc9..89a444a00693 100644
>> --- a/kernel/kexec_elf.c
>> +++ b/kernel/kexec_elf.c
>> @@ -172,7 +172,7 @@ static int elf_read_ehdr(const char *buf, size_t len, struct elfhdr *ehdr)
>>   
>>   	default:
>>   		pr_debug("Unknown ELF class.\n");
>> -		return -EINVAL;
>> +		return -ENOEXEC;
>>   	}
>>   
>>   	return elf_is_ehdr_sane(ehdr, len) ? 0 : -ENOEXEC;
>> @@ -236,7 +236,7 @@ static int elf_read_phdr(const char *buf, size_t len,
>>   
>>   	default:
>>   		pr_debug("Unknown ELF class.\n");
>> -		return -EINVAL;
>> +		return -ENOEXEC;
>>   	}
>>   
>>   	return elf_is_phdr_sane(phdr, len) ? 0 : -ENOEXEC;
>>
>> ---
>> base-commit: 28d012efb4327f9c75d5e042a7c91e9a542efa98
>> change-id: 20260813-mpilaniy-ffb0cc92c313
>>
>> Best regards,
>> --
>> Mukesh Pilaniya <mpilaniy@redhat.com>
>>
>