x86/ldt: Make modify_ldt synchronous

[linux.git] / arch / x86 / kernel / step.c

diff --git a/arch/x86/kernel/step.c b/arch/x86/kernel/step.c
index 9b4d51d0c0d013274f7ba46c2e58319f0d1d9145..6273324186ac5ca7adba69be5ded69f23d8882f7 100644 (file)
--- a/arch/x86/kernel/step.c
+++ b/arch/x86/kernel/step.c
@@ -5,6 +5,7 @@
 #include <linux/mm.h>
 #include <linux/ptrace.h>
 #include <asm/desc.h>
+#include <asm/mmu_context.h>
 
 unsigned long convert_ip_to_linear(struct task_struct *child, struct pt_regs *regs)
 {
@@ -30,10 +31,11 @@ unsigned long convert_ip_to_linear(struct task_struct *child, struct pt_regs *re
                seg &= ~7UL;
 
                mutex_lock(&child->mm->context.lock);
-               if (unlikely((seg >> 3) >= child->mm->context.size))
+               if (unlikely(!child->mm->context.ldt ||
+                            (seg >> 3) >= child->mm->context.ldt->size))
                        addr = -1L; /* bogus selector, access would fault */
                else {
-                       desc = child->mm->context.ldt + seg;
+                       desc = &child->mm->context.ldt->entries[seg];
                        base = get_desc_base(desc);
 
                        /* 16-bit code segment? */