Merge with /pub/scm/linux/kernel/git/torvalds/linux-2.6.git

Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 11 insertions, 3 deletions

diff --git a/arch/s390/kernel/process.c b/arch/s390/kernel/process.c
index 2ff90a1a1056..008c74526fd3 100644
--- a/arch/s390/kernel/process.c
+++ b/arch/s390/kernel/process.c
@@ -58,10 +58,18 @@ asmlinkage void ret_from_fork(void) __asm__("ret_from_fork");
  */
 unsigned long thread_saved_pc(struct task_struct *tsk)
 {
-        struct stack_frame *sf;
+        struct stack_frame *sf, *low, *high;
 
-        sf = (struct stack_frame *) tsk->thread.ksp;
-        sf = (struct stack_frame *) sf->back_chain;
+        if (!tsk || !task_stack_page(tsk))
+                return 0;
+        low = task_stack_page(tsk);
+        high = (struct stack_frame *) task_pt_regs(tsk);
+        sf = (struct stack_frame *) (tsk->thread.ksp & PSW_ADDR_INSN);
+        if (sf <= low || sf > high)
+                return 0;
+        sf = (struct stack_frame *) (sf->back_chain & PSW_ADDR_INSN);
+        if (sf <= low || sf > high)
+                return 0;
         return sf->gprs[8];
 }