Messages in this thread | | | Subject | Re: [PATCH] x86/xen: Delay get_cpu_cap until stack canary is established | From | Boris Ostrovsky <> | Date | Sat, 31 Mar 2018 14:10:49 -0400 |
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On 03/31/2018 01:38 PM, Jason Andryuk wrote: > On Wed, Mar 21, 2018, 5:12 PM Boris Ostrovsky > <boris.ostrovsky@oracle.com <mailto:boris.ostrovsky@oracle.com>> 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 <jandryuk@gmail.com > <mailto:jandryuk@gmail.com>> > > > > > Applied to for-linus-4.17 > > > Thanks. If it's not too late, can this be cc: stable?
We can always try ;-)
This is 4.15 and 4.16 only, I believe.
-boris
> If not, I'll > submit the request after it is in Linus's tree. > > -Jason >
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