2 files changed, 11 insertions, 1 deletions

diff --git a/arch/x86/kernel/ldt.c b/arch/x86/kernel/ldt.c
index af1d14a9ebda..dcbbaa165bde 100644
--- a/arch/x86/kernel/ldt.c
+++ b/arch/x86/kernel/ldt.c
@@ -20,6 +20,8 @@
 #include <asm/mmu_context.h>
 #include <asm/syscalls.h>
 
+int sysctl_ldt16 = 0;
+
 #ifdef CONFIG_SMP
 static void flush_ldt(void *current_mm)
 {
@@ -234,7 +236,7 @@ static int write_ldt(void __user *ptr, unsigned long bytecount, int oldmode)
          * IRET leaking the high bits of the kernel stack address.
          */
 #ifdef CONFIG_X86_64
-        if (!ldt_info.seg_32bit) {
+        if (!ldt_info.seg_32bit && !sysctl_ldt16) {
                 error = -EINVAL;
                 goto out_unlock;
         }
diff --git a/arch/x86/vdso/vdso32-setup.c b/arch/x86/vdso/vdso32-setup.c
index 00348980a3a6..e1f220e3ca68 100644
--- a/arch/x86/vdso/vdso32-setup.c
+++ b/arch/x86/vdso/vdso32-setup.c
@@ -39,6 +39,7 @@
 #ifdef CONFIG_X86_64
 #define vdso_enabled                    sysctl_vsyscall32
 #define arch_setup_additional_pages     syscall32_setup_pages
+extern int sysctl_ldt16;
 #endif
 
 /*
@@ -249,6 +250,13 @@ static struct ctl_table abi_table2[] = {
                 .mode           = 0644,
                 .proc_handler   = proc_dointvec
         },
+        {
+                .procname       = "ldt16",
+                .data           = &sysctl_ldt16,
+                .maxlen         = sizeof(int),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec
+        },
         {}
 };