sh: Fixup __strnlen_user() behaviour.

Drop TIF_USERSPACE and add addr_limit to the thread_info struct.
Subsequently, use that for address checking in strnlen_user() to
ward off bogus -EFAULTs.

Make __strnlen_user() return 0 on exception, rather than -EFAULT.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/arch/sh/kernel/process.c b/arch/sh/kernel/process.c
index f2031314cb2b..4a32550fd7c6 100644
--- a/arch/sh/kernel/process.c
+++ b/arch/sh/kernel/process.c
@@ -263,6 +263,7 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
                 unsigned long unused,
                 struct task_struct *p, struct pt_regs *regs)
 {
+        struct thread_info *ti = task_thread_info(p);
         struct pt_regs *childregs;
 #if defined(CONFIG_SH_FPU)
         struct task_struct *tsk = current;
@@ -277,8 +278,10 @@ int copy_thread(int nr, unsigned long clone_flags, unsigned long usp,
 
         if (user_mode(regs)) {
                 childregs->regs[15] = usp;
+                ti->addr_limit = USER_DS;
         } else {
                 childregs->regs[15] = (unsigned long)task_stack_page(p) + THREAD_SIZE;
+                ti->addr_limit = KERNEL_DS;
         }
         if (clone_flags & CLONE_SETTLS) {
                 childregs->gbr = childregs->regs[0];