[Lldb-commits] [PATCH] D71372: [lldb] Add additional validation on return address in 'thread step-out'

[Jim Ingham via Phabricator via lldb-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rG2a42a5a2f414 (authored by jingham).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D71372/new/

https://reviews.llvm.org/D71372

Files:
  lldb/include/lldb/Target/ThreadPlanStepOut.h
  lldb/source/Target/ThreadPlanStepOut.cpp
  lldb/test/Shell/Unwind/Inputs/thread-step-out-ret-addr-check.s
  lldb/test/Shell/Unwind/thread-step-out-ret-addr-check.test


Index: lldb/test/Shell/Unwind/thread-step-out-ret-addr-check.test
===================================================================
--- /dev/null
+++ lldb/test/Shell/Unwind/thread-step-out-ret-addr-check.test
@@ -0,0 +1,17 @@
+# Test that `thread step-out` fails when the "return address"
+# points to non-executable memory.
+
+# REQUIRES: target-x86_64, native
+
+# RUN: %clang_host %p/Inputs/call-asm.c %p/Inputs/thread-step-out-ret-addr-check.s -o %t
+# RUN: %lldb %t -s %s -b 2>&1 | FileCheck %s
+
+breakpoint set -n nonstandard_stub
+# CHECK: Breakpoint 1: where = {{.*}}`nonstandard_stub
+
+process launch
+# CHECK: stop reason = breakpoint 1.1
+
+thread step-out
+# CHECK: Could not create return address breakpoint.
+# CHECK: Return address (0x{{[a-f0-9]*}}) did not point to executable memory.
Index: lldb/test/Shell/Unwind/Inputs/thread-step-out-ret-addr-check.s
===================================================================
--- /dev/null
+++ lldb/test/Shell/Unwind/Inputs/thread-step-out-ret-addr-check.s
@@ -0,0 +1,20 @@
+        .text
+        .globl  asm_main
+asm_main:
+        sub $0x8, %rsp
+        movq $0, (%rsp)
+        push %rsp
+        jmp _nonstandard_stub
+
+# Takes a single pointer argument via the stack, which is nonstandard for x64.
+# Executing 'thread step-out' here will initially attempt to write a
+# breakpoint to that stack address, but should fail because of the executable
+# memory check.
+_nonstandard_stub:
+        mov (%rsp), %rdi
+        mov (%rdi), %rsi
+        add $1, %rsi
+        mov %rsi, (%rdi)
+
+        add $0x10, %rsp
+        ret
Index: lldb/source/Target/ThreadPlanStepOut.cpp
===================================================================
--- lldb/source/Target/ThreadPlanStepOut.cpp
+++ lldb/source/Target/ThreadPlanStepOut.cpp
@@ -126,6 +126,25 @@
     if (m_return_addr == LLDB_INVALID_ADDRESS)
       return;
 
+    // Perform some additional validation on the return address.
+    uint32_t permissions = 0;
+    if (!m_thread.GetProcess()->GetLoadAddressPermissions(m_return_addr,
+                                                          permissions)) {
+      m_constructor_errors.Printf("Return address (0x%" PRIx64
+                                  ") permissions not found.",
+                                  m_return_addr);
+      LLDB_LOGF(log, "ThreadPlanStepOut(%p): %s", static_cast<void *>(this),
+                m_constructor_errors.GetData());
+      return;
+    } else if (!(permissions & ePermissionsExecutable)) {
+      m_constructor_errors.Printf("Return address (0x%" PRIx64
+                                  ") did not point to executable memory.",
+                                  m_return_addr);
+      LLDB_LOGF(log, "ThreadPlanStepOut(%p): %s", static_cast<void *>(this),
+                m_constructor_errors.GetData());
+      return;
+    }
+
     Breakpoint *return_bp = m_thread.CalculateTarget()
                                 ->CreateBreakpoint(m_return_addr, true, false)
                                 .get();
@@ -238,8 +257,13 @@
   }
 
   if (m_return_bp_id == LLDB_INVALID_BREAK_ID) {
-    if (error)
+    if (error) {
       error->PutCString("Could not create return address breakpoint.");
+      if (m_constructor_errors.GetSize() > 0) {
+        error->PutCString(" ");
+        error->PutCString(m_constructor_errors.GetString());
+      }
+    }
     return false;
   }
 
Index: lldb/include/lldb/Target/ThreadPlanStepOut.h
===================================================================
--- lldb/include/lldb/Target/ThreadPlanStepOut.h
+++ lldb/include/lldb/Target/ThreadPlanStepOut.h
@@ -72,6 +72,7 @@
   std::vector<lldb::StackFrameSP> m_stepped_past_frames;
   lldb::ValueObjectSP m_return_valobj_sp;
   bool m_calculate_return_value;
+  StreamString m_constructor_errors;
 
   friend lldb::ThreadPlanSP Thread::QueueThreadPlanForStepOut(
       bool abort_other_plans, SymbolContext *addr_context, bool first_insn,

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