1 files changed, 9 insertions, 10 deletions

diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c
index 1dedc2c7ff49..dd56e11f339a 100644
--- a/arch/arm/kernel/unwind.c
+++ b/arch/arm/kernel/unwind.c
@@ -212,7 +212,8 @@ static int unwind_exec_insn(struct unwind_ctrl_block *ctrl)
                         ctrl->vrs[14] = *vsp++;
                 ctrl->vrs[SP] = (unsigned long)vsp;
         } else if (insn == 0xb0) {
-                ctrl->vrs[PC] = ctrl->vrs[LR];
+                if (ctrl->vrs[PC] == 0)
+                        ctrl->vrs[PC] = ctrl->vrs[LR];
                 /* no further processing */
                 ctrl->entries = 0;
         } else if (insn == 0xb1) {
@@ -309,18 +310,20 @@ int unwind_frame(struct stackframe *frame)
         }
 
         while (ctrl.entries > 0) {
-                int urc;
-
-                if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= high)
-                        return -URC_FAILURE;
-                urc = unwind_exec_insn(&ctrl);
+                int urc = unwind_exec_insn(&ctrl);
                 if (urc < 0)
                         return urc;
+                if (ctrl.vrs[SP] < low || ctrl.vrs[SP] >= high)
+                        return -URC_FAILURE;
         }
 
         if (ctrl.vrs[PC] == 0)
                 ctrl.vrs[PC] = ctrl.vrs[LR];
 
+        /* check for infinite loop */
+        if (frame->pc == ctrl.vrs[PC])
+                return -URC_FAILURE;
+
         frame->fp = ctrl.vrs[FP];
         frame->sp = ctrl.vrs[SP];
         frame->lr = ctrl.vrs[LR];
@@ -332,7 +335,6 @@ int unwind_frame(struct stackframe *frame)
 void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk)
 {
         struct stackframe frame;
-        unsigned long high, low;
         register unsigned long current_sp asm ("sp");
 
         pr_debug("%s(regs = %p tsk = %p)\n", __func__, regs, tsk);
@@ -362,9 +364,6 @@ void unwind_backtrace(struct pt_regs *regs, struct task_struct *tsk)
                 frame.pc = thread_saved_pc(tsk);
         }
 
-        low = frame.sp & ~(THREAD_SIZE - 1);
-        high = low + THREAD_SIZE;
-
         while (1) {
                 int urc;
                 unsigned long where = frame.pc;