x86_64: Zero extend all registers after ptrace in 32bit entry path.

[sfrench/cifs-2.6.git] / arch / x86_64 / kernel / ptrace.c

diff --git a/arch/x86_64/kernel/ptrace.c b/arch/x86_64/kernel/ptrace.c
index fa6775ef729f4a076f7a19341d48f50dd2248fe7..eea3702427b409d28c83c7e02a88c093a5c26232 100644 (file)
--- a/arch/x86_64/kernel/ptrace.c
+++ b/arch/x86_64/kernel/ptrace.c
@@ -102,16 +102,25 @@ unsigned long convert_rip_to_linear(struct task_struct *child, struct pt_regs *r
                u32 *desc;
                unsigned long base;
 
-               down(&child->mm->context.sem);
-               desc = child->mm->context.ldt + (seg & ~7);
-               base = (desc[0] >> 16) | ((desc[1] & 0xff) << 16) | (desc[1] & 0xff000000);
+               seg &= ~7UL;
 
-               /* 16-bit code segment? */
-               if (!((desc[1] >> 22) & 1))
-                       addr &= 0xffff;
-               addr += base;
+               down(&child->mm->context.sem);
+               if (unlikely((seg >> 3) >= child->mm->context.size))
+                       addr = -1L; /* bogus selector, access would fault */
+               else {
+                       desc = child->mm->context.ldt + seg;
+                       base = ((desc[0] >> 16) |
+                               ((desc[1] & 0xff) << 16) |
+                               (desc[1] & 0xff000000));
+
+                       /* 16-bit code segment? */
+                       if (!((desc[1] >> 22) & 1))
+                               addr &= 0xffff;
+                       addr += base;
+               }
                up(&child->mm->context.sem);
        }
+
        return addr;
 }
 
@@ -223,10 +232,6 @@ static int putreg(struct task_struct *child,
 {
        unsigned long tmp; 
        
-       /* Some code in the 64bit emulation may not be 64bit clean.
-          Don't take any chances. */
-       if (test_tsk_thread_flag(child, TIF_IA32))
-               value &= 0xffffffff;
        switch (regno) {
                case offsetof(struct user_regs_struct,fs):
                        if (value && (value & 3) != 3)