Messages in this thread | | | Date | Mon, 11 Mar 2013 14:20:34 -0700 | From | Greg KH <> | Subject | Re: + signal-always-clear-sa_restorer-on-execve.patch added to -mm tree |
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On Mon, Mar 11, 2013 at 02:01:30PM -0700, Andrew Morton 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...
I'll store it in my stable inbox and will hope to remember it when it hits Linus's tree...
thanks,
greg k-h
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