4.14-stable review patch. If anyone has any objections, please let me know.
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From: Boris Ostrovsky boris.ostrovsky@oracle.com
commit 98014068328c5574de9a4a30b604111fd9d8f901 upstream.
We are making calls to C code (e.g. xen_prepare_pvh()) which may use stack canary (stored in GS segment).
Signed-off-by: Boris Ostrovsky boris.ostrovsky@oracle.com Reviewed-by: Juergen Gross jgross@suse.com Signed-off-by: Juergen Gross jgross@suse.com Cc: Jason Andryuk jandryuk@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/x86/xen/xen-pvh.S | 26 +++++++++++++++++++++++++- 1 file changed, 25 insertions(+), 1 deletion(-)
--- a/arch/x86/xen/xen-pvh.S +++ b/arch/x86/xen/xen-pvh.S @@ -54,6 +54,9 @@ * charge of setting up it's own stack, GDT and IDT. */
+#define PVH_GDT_ENTRY_CANARY 4 +#define PVH_CANARY_SEL (PVH_GDT_ENTRY_CANARY * 8) + ENTRY(pvh_start_xen) cld
@@ -98,6 +101,12 @@ ENTRY(pvh_start_xen) /* 64-bit entry point. */ .code64 1: + /* Set base address in stack canary descriptor. */ + mov $MSR_GS_BASE,%ecx + mov $_pa(canary), %eax + xor %edx, %edx + wrmsr + call xen_prepare_pvh
/* startup_64 expects boot_params in %rsi. */ @@ -107,6 +116,17 @@ ENTRY(pvh_start_xen)
#else /* CONFIG_X86_64 */
+ /* Set base address in stack canary descriptor. */ + movl $_pa(gdt_start),%eax + movl $_pa(canary),%ecx + movw %cx, (PVH_GDT_ENTRY_CANARY * 8) + 2(%eax) + shrl $16, %ecx + movb %cl, (PVH_GDT_ENTRY_CANARY * 8) + 4(%eax) + movb %ch, (PVH_GDT_ENTRY_CANARY * 8) + 7(%eax) + + mov $PVH_CANARY_SEL,%eax + mov %eax,%gs + call mk_early_pgtbl_32
mov $_pa(initial_page_table), %eax @@ -150,9 +170,13 @@ gdt_start: .quad GDT_ENTRY(0xc09a, 0, 0xfffff) /* __KERNEL_CS */ #endif .quad GDT_ENTRY(0xc092, 0, 0xfffff) /* __KERNEL_DS */ + .quad GDT_ENTRY(0x4090, 0, 0x18) /* PVH_CANARY_SEL */ gdt_end:
- .balign 4 + .balign 16 +canary: + .fill 48, 1, 0 + early_stack: .fill 256, 1, 0 early_stack_end: