4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> 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@xxxxxxxxxx> Reviewed-by: Juergen Gross <jgross@xxxxxxxx> Signed-off-by: Juergen Gross <jgross@xxxxxxxx> Cc: Jason Andryuk <jandryuk@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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:
