lkml.org 
[lkml]   [2011]   [Oct]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRE: [PATCH v2] binfmt_elf: Fix PIE execution with randomization disabled (was Re: [RFC PATCH] binfmt_elf: Fix PIE execution with randomization disabled)
Why not

#if defined(CONFIG_X86) || defined(CONFIG_ARM)
#define CHECK_PF_RANDOMIZE 1
#else
#define CHECK_PF_RANDOMIZE 0
#endif
if (CHECK_PF_RANDOMIZE && (current->flags & PF_RANDOMIZE))
load_bias = 0;
else
load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
H.J.

> -----Original Message-----
> From: Nicolas Pitre [mailto:nicolas.pitre@linaro.org]
> Sent: Monday, October 03, 2011 8:56 AM
> To: Jiri Kosina
> Cc: Josh Boyer; Andrew Morton; Ingo Molnar; Lu, Hongjiu; linux-
> kernel@vger.kernel.org; Andrew Morton; Russell King
> Subject: Re: [PATCH v2] binfmt_elf: Fix PIE execution with randomization
> disabled (was Re: [RFC PATCH] binfmt_elf: Fix PIE execution with randomization
> disabled)
>
> On Mon, 3 Oct 2011, Jiri Kosina wrote:
>
> > How about the patch below instead? It survives my testing, and I believe
> > it handles both cases properly.
> >
> > Confirmation from the original bug reporter would obviously be a nice
> > bonus too :)
> >
> >
> >
> >
> > From: Jiri Kosina <jkosina@suse.cz>
> > Subject: [PATCH] binfmt_elf: fix PIE execution with randomization disabled
> >
> > The case of address space randomization being disabled in runtime through
> > randomize_va_space sysctl is not treated properly in load_elf_binary(),
> > resulting in SIGKILL coming at exec() time for certain PIE-linked binaries
> > in case the randomization has been disabled at runtime prior to calling
> > exec().
> >
> > Handle the randomize_va_space == 0 case the same way as if we were not
> > supporting .text randomization at all.
> >
> > Based on original patch by H.J. Lu <hongjiu.lu@intel.com> and
> > Josh Boyer <jwboyer@redhat.com>
> >
> > Cc: Ingo Molnar <mingo@elte.hu>
> > Cc: Jiri Kosina <jkosina@suse.cz>
> > Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
> > Cc: Russell King <rmk@arm.linux.org.uk>
> > Signed-off-by: Jiri Kosina <jkosina@suse.cz>
>
> Acked-by: Nicolas Pitre <nicolas.pitre@linaro.org>
>
> However I'd suggest a change to deal with style issues:
>
> > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c
> > index dd0fdfc..bb11fe4 100644
> > --- a/fs/binfmt_elf.c
> > +++ b/fs/binfmt_elf.c
> > @@ -795,7 +795,10 @@ static int load_elf_binary(struct linux_binprm *bprm,
> struct pt_regs *regs)
> > * might try to exec. This is because the brk will
> > * follow the loader, and is not movable. */
> > #if defined(CONFIG_X86) || defined(CONFIG_ARM)
> > - load_bias = 0;
> > + if (current->flags & PF_RANDOMIZE)
> > + load_bias = 0;
> > + else
> > + load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
> > #else
> > load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
> > #endif
>
> What about this instead, saving 3 lines out of 8:
>
> load_bias = ELF_PAGESTART(ELF_ET_DYN_BASE - vaddr);
> #if defined(CONFIG_X86) || defined(CONFIG_ARM)
> if (current->flags & PF_RANDOMIZE)
> load_bias = 0;
> #endif
>
>
> ?
>
>
> Nicolas


\
 
 \ /
  Last update: 2011-10-03 18:05    [from the cache]
©2003-2011 Jasper Spaans