Re: [PATCH v3 1/2] kexec: return -ENOEXEC from image probe functions on mismatch

On Tue, Aug 25, 2026 at 10:43:48AM +0530, Mukesh Pilaniya wrote:
> On 24/08/26 7:37 pm, Will Deacon wrote:
> > On Fri, Aug 21, 2026 at 07:19:57PM +0530, Mukesh Pilaniya 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 <[email protected]>
> >> Reviewed-by: Philipp Rudo <[email protected]>
> >> Reviewed-by: Pratyush Yadav <[email protected]>
> >> Reviewed-by: Bradley Morgan <[email protected]>
> >> ---
> >>  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(-)
> > 
> > Hmm, so after this patch, are there actually any implementations of .probe()
> > that return anything other than 0 or -ENOEXEC? I couldn't spot any after
> > a quick look.
> > 
> > Willkexec_elf_probe() can return -ENOMEM if memory allocation (kzalloc())
> fails inside elf_read_phdrs(). This behavior was previously discussed in
> the first patch of this series [1].

Fair enough, but I'd have thought it would be easier to special-case the
one -ENOMEM path instead of changing all the backends to return
-ENOEXEC all over the place (and hoping people don't start returning
-EINVAL again in future).

Will