Re: [Xen-devel] [PATCH v4 06/25] libelf-loader: introduce elf_load_image

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 09.01.12 at 18:59, <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> --- a/xen/common/libelf/libelf-loader.c
> +++ b/xen/common/libelf/libelf-loader.c
> @@ -107,11 +107,32 @@ void elf_set_log(struct elf_binary *elf, 
> elf_log_callback *log_callback,
>      elf->log_caller_data = log_caller_data;
>      elf->verbose = verbose;
>  }
> +
> +static int elf_load_image(void *dst, const void *src, uint64_t filesz, 
> uint64_t memsz)
> +{
> +    memcpy(dst, src, filesz);
> +    memset(dst + filesz, 0, memsz - filesz);
> +    return 0;
> +}
>  #else
> +#include <asm/guest_access.h>
> +
>  void elf_set_verbose(struct elf_binary *elf)
>  {
>      elf->verbose = 1;
>  }
> +
> +static int elf_load_image(void *dst, const void *src, uint64_t filesz, 
> uint64_t memsz)
> +{
> +    int rc;
> +    rc = raw_copy_to_guest(dst, src, filesz);
> +    if ( rc != 0 )
> +        return -rc;
> +    rc = raw_clear_guest(dst + filesz, memsz - filesz);
> +    if ( rc != 0 )
> +        return -rc;
> +    return 0;
> +}

I'm afraid a little more care is needed here: filesz and memsz being
64-bit values permits them to overflow the "long" of the functions
called. I think simply checking that both values fit in an unsigned long
will do for now.

Also, if you want to return a meaningful error code here, you also
need to consider that fact as well as the counts being unsigned (or
otherwise you could e.g. just return "bool").

Jan

>  #endif
>  
>  /* Calculate the required additional kernel space for the elf image */



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