Ticket #9247: debugger_nullptr_crash.patch

src/apps/debugger/arch/x86/ArchitectureX86.cpp

@@ -309 +309 @@
         // If the function is not frameless and we're at the top frame we need
         // to check whether the prologue has not been executed (completely) or
         // we're already after the epilogue.
-        if (hasPrologue && isTopFrame) {
+        if (isTopFrame) {
             uint32 stack = 0;
-            if (eip < function->Address() + 3) {
-                // The prologue has not been executed yet, i.e. there's no
-                // stack frame yet. Get the return address from the stack.
-                stack = cpuState->IntRegisterValue(X86_REGISTER_ESP);
-                if (eip > function->Address()) {
-                    // The "push %ebp" has already been executed.
-                    stack += 4;
+            if (hasPrologue) {
+                if (eip < function->Address() + 3) {
+                    // The prologue has not been executed yet, i.e. there's no
+                    // stack frame yet. Get the return address from the stack.
+                    stack = cpuState->IntRegisterValue(X86_REGISTER_ESP);
+                    if (eip > function->Address()) {
+                        // The "push %ebp" has already been executed.
+                        stack += 4;
+                    }
+                } else {
+                    // Not in the function prologue, but maybe after the
+                    // epilogue. The epilogue is a single "pop %ebp", so we
+                    // check whether the current instruction is already a
+                    // "ret".
+                    uint8 code[1];
+                    if (fTeamMemory->ReadMemory(eip, &code, 1) == 1
+                        && code[0] == 0xc3) {
+                        stack = cpuState->IntRegisterValue(X86_REGISTER_ESP);
+                    }
                 }
             } else {
-                // Not in the function prologue, but maybe after the epilogue.
-                // The epilogue is a single "pop %ebp", so we check whether the
-                // current instruction is already a "ret".
-                uint8 code[1];
-                if (fTeamMemory->ReadMemory(eip, &code, 1) == 1
-                    && code[0] == 0xc3) {
+                // in the case of a NULL function pointer, the prologue
+                // has, by definition not been executed. In such a case,
+                // everything we need is right at the top of the stack.
+                if (eip == 0)
                     stack = cpuState->IntRegisterValue(X86_REGISTER_ESP);
-                }
             }
 
             if (stack != 0) {