Fix build with gcc-4.8 and array boundaries issue

Remove unused parameters of static functions to avoid warning with 4.8.
Fix array index out of bounds issue when register number exceeds limit.
It shouldn't occur in real world, but static verifiers can detect it.

Change-Id: Id237df905b40bad02fc8cbbeac31084040f58076
Signed-off-by: Pavel Chupin <pavel.v.chupin@intel.com>

1 files changed, 14 insertions, 15 deletions

diff --git a/libcorkscrew/arch-x86/backtrace-x86.c b/libcorkscrew/arch-x86/backtrace-x86.c
index e133ab6..ef22821 100755
--- a/libcorkscrew/arch-x86/backtrace-x86.c
+++ b/libcorkscrew/arch-x86/backtrace-x86.c
@@ -380,7 +380,7 @@ static bool execute_dwarf(const memory_t* memory, uintptr_t ptr, cie_info_t* cie
         case DW_CFA_offset_extended: // probably we don't have it on x86.
             if (!try_get_uleb128(memory, ptr, &reg, cursor)) return false;
             if (!try_get_uleb128(memory, ptr, &offset, cursor)) return false;
-            if (reg > DWARF_REGISTERS) {
+            if (reg >= DWARF_REGISTERS) {
                 ALOGE("DW_CFA_offset_extended: r%d exceeds supported number of registers (%d)", reg, DWARF_REGISTERS);
                 return false;
             }
@@ -390,39 +390,39 @@ static bool execute_dwarf(const memory_t* memory, uintptr_t ptr, cie_info_t* cie
             break;
         case DW_CFA_restore_extended: // probably we don't have it on x86.
             if (!try_get_uleb128(memory, ptr, &reg, cursor)) return false;
-            dstate->regs[reg].rule = stack->regs[reg].rule;
-            dstate->regs[reg].value = stack->regs[reg].value;
-            if (reg > DWARF_REGISTERS) {
+            if (reg >= DWARF_REGISTERS) {
                 ALOGE("DW_CFA_restore_extended: r%d exceeds supported number of registers (%d)", reg, DWARF_REGISTERS);
                 return false;
             }
+            dstate->regs[reg].rule = stack->regs[reg].rule;
+            dstate->regs[reg].value = stack->regs[reg].value;
             ALOGV("DW_CFA_restore: r%d = %c(%d)", reg, dstate->regs[reg].rule, dstate->regs[reg].value);
             break;
         case DW_CFA_undefined: // probably we don't have it on x86.
             if (!try_get_uleb128(memory, ptr, &reg, cursor)) return false;
-            dstate->regs[reg].rule = 'u';
-            dstate->regs[reg].value = 0;
-            if (reg > DWARF_REGISTERS) {
+            if (reg >= DWARF_REGISTERS) {
                 ALOGE("DW_CFA_undefined: r%d exceeds supported number of registers (%d)", reg, DWARF_REGISTERS);
                 return false;
             }
+            dstate->regs[reg].rule = 'u';
+            dstate->regs[reg].value = 0;
             ALOGV("DW_CFA_undefined: r%d", reg);
             break;
         case DW_CFA_same_value: // probably we don't have it on x86.
             if (!try_get_uleb128(memory, ptr, &reg, cursor)) return false;
-            dstate->regs[reg].rule = 's';
-            dstate->regs[reg].value = 0;
-            if (reg > DWARF_REGISTERS) {
+            if (reg >= DWARF_REGISTERS) {
                 ALOGE("DW_CFA_undefined: r%d exceeds supported number of registers (%d)", reg, DWARF_REGISTERS);
                 return false;
             }
+            dstate->regs[reg].rule = 's';
+            dstate->regs[reg].value = 0;
             ALOGV("DW_CFA_same_value: r%d", reg);
             break;
         case DW_CFA_register: // probably we don't have it on x86.
             if (!try_get_uleb128(memory, ptr, &reg, cursor)) return false;
             /* that's new register actually, not offset */
             if (!try_get_uleb128(memory, ptr, &offset, cursor)) return false;
-            if (reg > DWARF_REGISTERS || offset > DWARF_REGISTERS) {
+            if (reg >= DWARF_REGISTERS || offset >= DWARF_REGISTERS) {
                 ALOGE("DW_CFA_register: r%d or r%d exceeds supported number of registers (%d)", reg, offset, DWARF_REGISTERS);
                 return false;
             }
@@ -520,7 +520,7 @@ static bool get_old_register_value(const memory_t* memory, uint32_t cfa,
 
 /* Updaing state based on dwarf state. */
 static bool update_state(const memory_t* memory, unwind_state_t* state,
-                         dwarf_state_t* dstate, cie_info_t* cie_info) {
+                         dwarf_state_t* dstate) {
     unwind_state_t newstate;
     /* We can restore more registers here if we need them. Meanwile doing minimal work here. */
     /* Getting CFA. */
@@ -550,7 +550,6 @@ static bool update_state(const memory_t* memory, unwind_state_t* state,
 
 /* Execute CIE and FDE instructions for FDE found with find_fde. */
 static bool execute_fde(const memory_t* memory,
-                        const map_info_t* map_info_list,
                         uintptr_t fde,
                         unwind_state_t* state) {
     uint32_t fde_length = 0;
@@ -753,7 +752,7 @@ static bool execute_fde(const memory_t* memory,
         ALOGV("IP: %x, LOC: %x", state->reg[DWARF_EIP], dstate->loc);
     }
 
-    return update_state(memory, state, dstate, cie_info);
+    return update_state(memory, state, dstate);
 }
 
 static ssize_t unwind_backtrace_common(const memory_t* memory,
@@ -805,7 +804,7 @@ static ssize_t unwind_backtrace_common(const memory_t* memory,
 
         uint32_t stack_top = state->reg[DWARF_ESP];
 
-        if (!execute_fde(memory, map_info_list, fde, state)) break;
+        if (!execute_fde(memory, fde, state)) break;
 
         if (frame) {
             frame->stack_top = stack_top;