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| author | Jason Andryuk <jandryuk@gmail.com> | 2018-03-19 12:58:04 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-24 09:36:25 +0200 |
| commit | e7b00dc28275a1883749d319081484e3306dc265 (patch) | |
| tree | 7be102c960f9f974be8a6d1e544793c3bc79f5fc | |
| parent | fcd054c733cf702f192e01fa7e78596cc07df771 (diff) | |
| download | linux-stable-e7b00dc28275a1883749d319081484e3306dc265.tar.gz linux-stable-e7b00dc28275a1883749d319081484e3306dc265.tar.bz2 linux-stable-e7b00dc28275a1883749d319081484e3306dc265.zip | |
x86/xen: Delay get_cpu_cap until stack canary is established
commit 36104cb9012a82e73c32a3b709257766b16bcd1d upstream.
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>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/xen/enlighten_pv.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index f896c2975545..fcd8789470d1 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -1258,10 +1258,6 @@ asmlinkage __visible void __init xen_start_kernel(void) */ __userpte_alloc_gfp &= ~__GFP_HIGHMEM; - /* Work out if we support NX */ - get_cpu_cap(&boot_cpu_data); - x86_configure_nx(); - /* Get mfn list */ xen_build_dynamic_phys_to_machine(); @@ -1271,6 +1267,10 @@ asmlinkage __visible void __init xen_start_kernel(void) */ xen_setup_gdt(0); + /* Work out if we support NX */ + get_cpu_cap(&boot_cpu_data); + x86_configure_nx(); + xen_init_irq_ops(); /* Let's presume PV guests always boot on vCPU with id 0. */ |