Re: [Xen-devel] [PATCH v3 06/25] libelf-loader: introduce elf_load_image

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Thu, 15 Dec 2011, Jan Beulich wrote:
> >>> On 15.12.11 at 17:30, <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> > From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > 
> > Implement a new function, called elf_load_image, to perform the actually
> > copy of the elf image and clearing the padding.
> > The function is implemented as memcpy and memset when the library is
> > built as part of the tools, but it is implemented as raw_copy_to_guest and
> > raw_clear_guest when built as part of Xen, so that it can be safely called
> > with an HVM style dom0.
> > 
> > 
> > Changes in v3:
> > 
> > - switch to raw_copy_to_guest and raw_clear_guest.
> > 
> > 
> > Changes in v2:
> > 
> > - remove CONFIG_KERNEL_NO_RELOC.
> > 
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> > Signed-off-by: Tim Deegan <Tim.Deegan@xxxxxxxxxx>
> > ---
> >  xen/common/libelf/libelf-loader.c |   17 +++++++++++++++--
> >  1 files changed, 15 insertions(+), 2 deletions(-)
> > 
> > diff --git a/xen/common/libelf/libelf-loader.c 
> > b/xen/common/libelf/libelf-loader.c
> > index 1ccf7d3..d2cb5b3 100644
> > --- a/xen/common/libelf/libelf-loader.c
> > +++ b/xen/common/libelf/libelf-loader.c
> > @@ -107,11 +107,25 @@ void elf_set_log(struct elf_binary *elf, 
> > elf_log_callback *log_callback,
> >      elf->log_caller_data = log_caller_data;
> >      elf->verbose = verbose;
> >  }
> > +
> > +static void elf_load_image(void *dst, const void *src, uint64_t filesz, 
> > uint64_t memsz)
> > +{
> > +    memcpy(dst, src, filesz);
> > +    memset(dst + filesz, 0, memsz - filesz);
> > +}
> >  #else
> > +#include <asm/guest_access.h>
> > +
> >  void elf_set_verbose(struct elf_binary *elf)
> >  {
> >      elf->verbose = 1;
> >  }
> > +
> > +static void elf_load_image(void *dst, const void *src, uint64_t filesz, 
> > uint64_t memsz)
> > +{
> > +    raw_copy_to_guest(dst, src, filesz);
> > +    raw_clear_guest(dst + filesz, memsz - filesz);
> 
> I thought I had mentioned this already - calling user/guest access
> functions without checking their return value is bogus.

I am going to add two checks here and print a message in case of errors,
however I am not going to propagate the error up, considering that there
is no error checking in elf_load_binary and it doesn't return an error.
Would that be OK for you?

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