On Sat, Mar 31, 2018 at 2:10 PM, Boris Ostrovsky <boris.ostrov...@oracle.com> wrote: > On 03/31/2018 01:38 PM, Jason Andryuk wrote: >> On Wed, Mar 21, 2018, 5:12 PM Boris Ostrovsky <boris.ostrov...@oracle.com >> <mailto:boris.ostrov...@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 <jandr...@gmail.com >> <mailto:jandr...@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.
I'm using this patch on 4.14, so there as well. -Jason
