[PATCH] x86_64: check if ptrace RIP is canonical

This works around an AMD Erratum.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/x86_64/kernel/ptrace.c

@@ -277,6 +277,11 @@ static int putreg(struct task_struct *child,
 				return -EIO;
 			value &= 0xffff;
 			break;
+		case offsetof(struct user_regs_struct, rip):
+			/* Check if the new RIP address is canonical */
+			if (value >= TASK_SIZE)
+				return -EIO;
+			break;
 	}
 	put_stack_long(child, regno - sizeof(struct pt_regs), value);
 	return 0;