On Wed, Mar 21, 2018, 5:12 PM Boris Ostrovsky <[email protected]>
wrote:
> On 03/19/2018 12:58 PM, Jason Andryuk wrote:
> > Commit 2cc42bac1c79 ("x86-64/Xen: eliminate W+X mappings") introduced a
> > call to get_cpu_cap, which is fstack-protected. This is works on x86-64
> > as commit 4f277295e54c ("x86/xen: init %gs very early to avoid page
> > faults with stack protector") ensures the stack protector is configured,
> > but it it did not cover x86-32.
> >
> > Delay calling get_cpu_cap until after xen_setup_gdt has initialized the
> > stack canary. Without this, a 32bit PV machine crashes early
> > in boot.
> > (XEN) Domain 0 (vcpu#0) crashed on cpu#0:
> > (XEN) ----[ Xen-4.6.6-xc x86_64 debug=n Tainted: C ]----
> > (XEN) CPU: 0
> > (XEN) RIP: e019:[<00000000c10362f8>]
> >
> > And the PV kernel IP corresponds to init_scattered_cpuid_features
> > 0xc10362f8 <+24>: mov %gs:0x14,%eax
> >
> > Fixes 2cc42bac1c79 ("x86-64/Xen: eliminate W+X mappings")
> >
> > Signed-off-by: Jason Andryuk <[email protected]>
> >
>
>
> Applied to for-linus-4.17
>
Thanks. If it's not too late, can this be cc: stable? If not, I'll submit
the request after it is in Linus's tree.
-Jason
>
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