[PATCH] D85523: [clang-tidy] Fix a crash in bugprone-not-null-terminated-result check when `__STDC_WANT_LIB_EXT1__` was undefined after definition.

[Aleksandr Platonov via Phabricator via cfe-commits]

ArcsinX created this revision.
Herald added subscribers: cfe-commits, xazax.hun.
Herald added a project: clang.
ArcsinX requested review of this revision.

PP->getMacroInfo() returns nullptr for undefined macro, so we need to check 
this return value before dereference.
Stack dump:

  #0 0x0000000002185e6a llvm::sys::PrintStackTrace(llvm::raw_ostream&) 
(/llvm-project/build/bin/clang-tidy+0x2185e6a)
  #1 0x0000000002183e8c llvm::sys::RunSignalHandlers() 
(/llvm-project/build/bin/clang-tidy+0x2183e8c)
  #2 0x0000000002183ff3 SignalHandler(int) 
(/llvm-project/build/bin/clang-tidy+0x2183ff3)
  #3 0x00007f37df9b1390 __restore_rt 
(/lib/x86_64-linux-gnu/libpthread.so.0+0x11390)
  #4 0x000000000052054e 
clang::tidy::bugprone::NotNullTerminatedResultCheck::check(clang::ast_matchers::MatchFinder::MatchResult
 const&) (/llvm-project/build/bin/clang-tidy+0x52054e)


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D85523

Files:
  clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
  
clang-tools-extra/test/clang-tidy/checkers/bugprone-not-null-terminated-result-undef-stdc-want-lib-ext1.c


Index: 
clang-tools-extra/test/clang-tidy/checkers/bugprone-not-null-terminated-result-undef-stdc-want-lib-ext1.c
===================================================================
--- /dev/null
+++ 
clang-tools-extra/test/clang-tidy/checkers/bugprone-not-null-terminated-result-undef-stdc-want-lib-ext1.c
@@ -0,0 +1,16 @@
+// RUN: %check_clang_tidy %s bugprone-not-null-terminated-result %t -- \
+// RUN: -- -std=c11 -I %S/Inputs/bugprone-not-null-terminated-result
+
+#include "not-null-terminated-result-c.h"
+
+#define __STDC_LIB_EXT1__ 1
+#define __STDC_WANT_LIB_EXT1__ 1
+#undef __STDC_WANT_LIB_EXT1__
+
+void f(const char *src) {
+  char dest[13];
+  memcpy_s(dest, 13, src, strlen(src) - 1);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: the result from calling 
'memcpy_s' is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: char dest[14];
+  // CHECK-FIXES-NEXT: strncpy_s(dest, 14, src, strlen(src) - 1);
+}
\ No newline at end of file
Index: clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
+++ clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
@@ -802,11 +802,14 @@
     while (It != PP->macro_end() && !AreSafeFunctionsWanted.hasValue()) {
       if (It->first->getName() == "__STDC_WANT_LIB_EXT1__") {
         const auto *MI = PP->getMacroInfo(It->first);
-        const auto &T = MI->tokens().back();
-        StringRef ValueStr = StringRef(T.getLiteralData(), T.getLength());
-        llvm::APInt IntValue;
-        ValueStr.getAsInteger(10, IntValue);
-        AreSafeFunctionsWanted = IntValue.getZExtValue();
+        // PP->getMacroInfo() returns nullptr if macro has no definition.
+        if (MI) {
+          const auto &T = MI->tokens().back();
+          StringRef ValueStr = StringRef(T.getLiteralData(), T.getLength());
+          llvm::APInt IntValue;
+          ValueStr.getAsInteger(10, IntValue);
+          AreSafeFunctionsWanted = IntValue.getZExtValue();
+        }
       }
 
       ++It;



Index: clang-tools-extra/test/clang-tidy/checkers/bugprone-not-null-terminated-result-undef-stdc-want-lib-ext1.c
===================================================================
--- /dev/null
+++ clang-tools-extra/test/clang-tidy/checkers/bugprone-not-null-terminated-result-undef-stdc-want-lib-ext1.c
@@ -0,0 +1,16 @@
+// RUN: %check_clang_tidy %s bugprone-not-null-terminated-result %t -- \
+// RUN: -- -std=c11 -I %S/Inputs/bugprone-not-null-terminated-result
+
+#include "not-null-terminated-result-c.h"
+
+#define __STDC_LIB_EXT1__ 1
+#define __STDC_WANT_LIB_EXT1__ 1
+#undef __STDC_WANT_LIB_EXT1__
+
+void f(const char *src) {
+  char dest[13];
+  memcpy_s(dest, 13, src, strlen(src) - 1);
+  // CHECK-MESSAGES: :[[@LINE-1]]:3: warning: the result from calling 'memcpy_s' is not null-terminated [bugprone-not-null-terminated-result]
+  // CHECK-FIXES: char dest[14];
+  // CHECK-FIXES-NEXT: strncpy_s(dest, 14, src, strlen(src) - 1);
+}
\ No newline at end of file
Index: clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
+++ clang-tools-extra/clang-tidy/bugprone/NotNullTerminatedResultCheck.cpp
@@ -802,11 +802,14 @@
     while (It != PP->macro_end() && !AreSafeFunctionsWanted.hasValue()) {
       if (It->first->getName() == "__STDC_WANT_LIB_EXT1__") {
         const auto *MI = PP->getMacroInfo(It->first);
-        const auto &T = MI->tokens().back();
-        StringRef ValueStr = StringRef(T.getLiteralData(), T.getLength());
-        llvm::APInt IntValue;
-        ValueStr.getAsInteger(10, IntValue);
-        AreSafeFunctionsWanted = IntValue.getZExtValue();
+        // PP->getMacroInfo() returns nullptr if macro has no definition.
+        if (MI) {
+          const auto &T = MI->tokens().back();
+          StringRef ValueStr = StringRef(T.getLiteralData(), T.getLength());
+          llvm::APInt IntValue;
+          ValueStr.getAsInteger(10, IntValue);
+          AreSafeFunctionsWanted = IntValue.getZExtValue();
+        }
       }
 
       ++It;

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