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SubjectRe: [PATCH] ELF: implement AT_RANDOM for future glibc use
On Fri, Oct 03, 2008 at 02:43:40AM +0200, Jakub Jelinek wrote:
> On Thu, Oct 02, 2008 at 05:16:16PM -0700, Kees Cook wrote:
> > @@ -196,6 +198,18 @@ create_elf_tables(struct linux_binprm *bprm, struct elfhdr *exec,
> > return -EFAULT;
> > }
> >
> > + rand_size = CONFIG_SECURITY_AUXV_RANDOM_SIZE * sizeof(unsigned long);
>
> I believe you want sizeof (elf_addr_t) here instead.
>
> > + u_rand_bytes = NULL;
> > + if (rand_size) {
> > + unsigned char k_rand_bytes[CONFIG_SECURITY_AUXV_RANDOM_SIZE *
> > + sizeof(unsigned long)];
>
> And here too, because having a 64-bit kernel supply twice as much random
> data to 32-bit programs as a 32-bit kernel would supply would be certainly
> unexpected.

Ah-ha! I see the 32-vs-64 elf_addr_t magic in fs/compat_binfmt_elf.c now.
Excellent, I will send an updated patch.

Thanks!

-Kees

--
Kees Cook
Ubuntu Security Team


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