[Lldb-commits] [PATCH] D83343: [lldb/api] Add checks for StackFrame::GetRegisterContext calls (NFC)

[Med Ismail Bennani via Phabricator via lldb-commits]

mib created this revision.
mib added reviewers: teemperor, JDevlieghere.
mib added a project: LLDB.
Herald added a subscriber: lldb-commits.

This patch fixes a crash that is happening because of a null pointer
dereference in SBFrame.

StackFrame::GetRegisterContext says explicitly that you might not get
a valid RegisterContext back but the pointer wasn't tested before,
resulting in crashes. This should solve the issue.

rdar://54462095

Signed-off-by: Med Ismail Bennani <medismail.bennani at gmail.com>


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D83343

Files:
  lldb/source/API/SBFrame.cpp


Index: lldb/source/API/SBFrame.cpp
===================================================================
--- lldb/source/API/SBFrame.cpp
+++ lldb/source/API/SBFrame.cpp
@@ -361,9 +361,11 @@
     Process::StopLocker stop_locker;
     if (stop_locker.TryLock(&process->GetRunLock())) {
       frame = exe_ctx.GetFramePtr();
-      if (frame) {
-        ret_val = frame->GetRegisterContext()->SetPC(new_pc);
-      }
+      RegisterContextSP reg_ctx_sp = nullptr;
+      if (frame)
+        reg_ctx_sp = frame->GetRegisterContext();
+      if (reg_ctx_sp)
+        ret_val = reg_ctx_sp->SetPC(new_pc);
     }
   }
 
@@ -384,9 +386,11 @@
     Process::StopLocker stop_locker;
     if (stop_locker.TryLock(&process->GetRunLock())) {
       frame = exe_ctx.GetFramePtr();
-      if (frame) {
-        addr = frame->GetRegisterContext()->GetSP();
-      }
+      RegisterContextSP reg_ctx_sp = nullptr;
+      if (frame)
+        reg_ctx_sp = frame->GetRegisterContext();
+      if (reg_ctx_sp)
+        addr = reg_ctx_sp->GetSP();
     }
   }
 
@@ -407,8 +411,11 @@
     Process::StopLocker stop_locker;
     if (stop_locker.TryLock(&process->GetRunLock())) {
       frame = exe_ctx.GetFramePtr();
+      RegisterContextSP reg_ctx_sp = nullptr;
       if (frame)
-        addr = frame->GetRegisterContext()->GetFP();
+        reg_ctx_sp = frame->GetRegisterContext();
+      if (reg_ctx_sp)
+        addr = reg_ctx_sp->GetFP();
     }
   }
 


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