[Lldb-commits] [PATCH] D86355: Consume error for valid return from Target::GetEntryPointAddress()

[Dimitry Andric via Phabricator via lldb-commits]

dim created this revision.
dim added reviewers: aprantl, emaste, JDevlieghere, jingham.
Herald added subscribers: krytarowski, arichardson.
Herald added a project: LLDB.
dim requested review of this revision.

When `Target::GetEntryPointAddress()` calls
`exe_module->GetObjectFile()->GetEntryPointAddress()`, and the returned
`entry_addr` is valid, it can immediately be returned.

However, just before that, an `llvm::Error` value has been setup, but in
this case it is not consumed before returning, like is done further
below in the function.

In https://bugs.freebsd.org/248745 we got a bug report for this, where a
very simple test case aborts and dumps core:

  * thread #1, name = 'testcase', stop reason = breakpoint 1.1
      frame #0: 0x00000000002018d4 testcase`main(argc=1, argv=0x00007fffffffea18) at testcase.c:3:5
     1	int main(int argc, char *argv[])
     2	{
  -> 3	    return 0;
     4	}
  (lldb) p argc
  Program aborted due to an unhandled Error:
  Error value was Success. (Note: Success values must still be checked prior to being destroyed).
  
  Thread 1 received signal SIGABRT, Aborted.
  thr_kill () at thr_kill.S:3
  3	thr_kill.S: No such file or directory.
  (gdb) bt
  #0  thr_kill () at thr_kill.S:3
  #1  0x00000008049a0004 in __raise (s=6) at /usr/src/lib/libc/gen/raise.c:52
  #2  0x0000000804916229 in abort () at /usr/src/lib/libc/stdlib/abort.c:67
  #3  0x000000000451b5f5 in fatalUncheckedError () at /usr/src/contrib/llvm-project/llvm/lib/Support/Error.cpp:112
  #4  0x00000000019cf008 in GetEntryPointAddress () at /usr/src/contrib/llvm-project/llvm/include/llvm/Support/Error.h:267
  #5  0x0000000001bccbd8 in ConstructorSetup () at /usr/src/contrib/llvm-project/lldb/source/Target/ThreadPlanCallFunction.cpp:67
  #6  0x0000000001bcd2c0 in ThreadPlanCallFunction () at /usr/src/contrib/llvm-project/lldb/source/Target/ThreadPlanCallFunction.cpp:114
  #7  0x00000000020076d4 in InferiorCallMmap () at /usr/src/contrib/llvm-project/lldb/source/Plugins/Process/Utility/InferiorCallPOSIX.cpp:97
  #8  0x0000000001f4be33 in DoAllocateMemory () at /usr/src/contrib/llvm-project/lldb/source/Plugins/Process/FreeBSD/ProcessFreeBSD.cpp:604
  #9  0x0000000001fe51b9 in AllocatePage () at /usr/src/contrib/llvm-project/lldb/source/Target/Memory.cpp:347
  #10 0x0000000001fe5385 in AllocateMemory () at /usr/src/contrib/llvm-project/lldb/source/Target/Memory.cpp:383
  #11 0x0000000001974da2 in AllocateMemory () at /usr/src/contrib/llvm-project/lldb/source/Target/Process.cpp:2301
  #12 CanJIT () at /usr/src/contrib/llvm-project/lldb/source/Target/Process.cpp:2331
  #13 0x0000000001a1bf3d in Evaluate () at /usr/src/contrib/llvm-project/lldb/source/Expression/UserExpression.cpp:190
  #14 0x00000000019ce7a2 in EvaluateExpression () at /usr/src/contrib/llvm-project/lldb/source/Target/Target.cpp:2372
  #15 0x0000000001ad784c in EvaluateExpression () at /usr/src/contrib/llvm-project/lldb/source/Commands/CommandObjectExpression.cpp:414
  #16 0x0000000001ad86ae in DoExecute () at /usr/src/contrib/llvm-project/lldb/source/Commands/CommandObjectExpression.cpp:646
  #17 0x0000000001a5e3ed in Execute () at /usr/src/contrib/llvm-project/lldb/source/Interpreter/CommandObject.cpp:1003
  #18 0x0000000001a6c4a3 in HandleCommand () at /usr/src/contrib/llvm-project/lldb/source/Interpreter/CommandInterpreter.cpp:1762
  #19 0x0000000001a6f98c in IOHandlerInputComplete () at /usr/src/contrib/llvm-project/lldb/source/Interpreter/CommandInterpreter.cpp:2760
  #20 0x0000000001a90b08 in Run () at /usr/src/contrib/llvm-project/lldb/source/Core/IOHandler.cpp:548
  #21 0x00000000019a6c6a in ExecuteIOHandlers () at /usr/src/contrib/llvm-project/lldb/source/Core/Debugger.cpp:903
  #22 0x0000000001a70337 in RunCommandInterpreter () at /usr/src/contrib/llvm-project/lldb/source/Interpreter/CommandInterpreter.cpp:2946
  #23 0x0000000001d9d812 in RunCommandInterpreter () at /usr/src/contrib/llvm-project/lldb/source/API/SBDebugger.cpp:1169
  #24 0x0000000001918be8 in MainLoop () at /usr/src/contrib/llvm-project/lldb/tools/driver/Driver.cpp:675
  #25 0x000000000191a114 in main () at /usr/src/contrib/llvm-project/lldb/tools/driver/Driver.cpp:890

Fix the incorrect error catch by explicitly consuming the error, similar
to the `module_sp->GetObjectFile()->GetEntryPointAddress()` return path.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D86355

Files:
  lldb/source/Target/Target.cpp


Index: lldb/source/Target/Target.cpp
===================================================================
--- lldb/source/Target/Target.cpp
+++ lldb/source/Target/Target.cpp
@@ -2415,8 +2415,11 @@
                                                 llvm::inconvertibleErrorCode());
   } else {
     Address entry_addr = exe_module->GetObjectFile()->GetEntryPointAddress();
-    if (entry_addr.IsValid())
+    if (entry_addr.IsValid()) {
+      // Discard the error.
+      llvm::consumeError(std::move(error));
       return entry_addr;
+    }
 
     error = llvm::make_error<llvm::StringError>(
         "Could not find entry point address for executable module \"" +


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