Messages in this thread | | | Date | Mon, 11 Mar 2013 14:22:18 -0700 | From | Andrew Morton <> | Subject | Re: + signal-always-clear-sa_restorer-on-execve.patch added to -mm tree |
| |
On Mon, 11 Mar 2013 14:03:20 -0700 Kees Cook <keescook@chromium.org> wrote:
> On Mon, Mar 11, 2013 at 2:01 PM, Andrew Morton > <akpm@linux-foundation.org> wrote: > > On Mon, 11 Mar 2013 13:37:53 -0700 Kees Cook <keescook@chromium.org> wrote: > > > >> ... > >> > > > > (pop toasting undone) > > > >> > Subject: signal: always clear sa_restorer on execve > >> > > >> > When the new signal handlers are set up, the location of sa_restorer is > >> > not cleared, leaking a parent process's address space location to > >> > children. This allows for a potential bypass of the parent's ASLR by > >> > examining the sa_restorer value returned when calling sigaction(). > >> > > >> > Based on what should be considered "secret" about addresses, it only > >> > matters across the exec not the fork (since the VMAs haven't changed until > >> > the exec). But since exec sets SIG_DFL and keeps sa_restorer, this is > >> > where it should be fixed. > >> > >> A note for backporters: you'll likely want to change > >> __ARCH_HAS_SA_RESTORER to SA_RESTORER, since the former was recently > >> introduced. If not, this will apply but not actually do any good. > > > > I added this to the changelog, but I fear people won't read it! Is > > there any clever way in which we can have one patch which will work OK > > in both old and new kernels? I can't think of one... > > Using just SA_RESTORER will work in both cases, but isn't "correct" > going forward. :(
That's easy.
patch #1: use SA_RESTORER, cc stable (please promise me this will work OK) patch #2: switch to __ARCH_HAS_SA_RESTORER, no cc stable
I'm assuming this is all for 3.10, btw. If you think it should be in 3.9 then you need to write scarier changelogs.
| |