[clang] [webkit.UncountedLambdaCapturesChecker] Fix a crash in declProtectsThis (PR #127309)

[Ryosuke Niwa via cfe-commits]

https://github.com/rniwa updated https://github.com/llvm/llvm-project/pull/127309

>From 715da2e5ec5cd64416a5dab9017a9c43a6ca8e78 Mon Sep 17 00:00:00 2001
From: Ryosuke Niwa <rniwa at webkit.org>
Date: Sat, 15 Feb 2025 01:33:47 -0800
Subject: [PATCH 1/2] [webkit.UncountedLambdaCapturesChecker] Fix a crash in
 declProtectsThis

Add a missing nullptr check to declProtectsThis.
---
 .../WebKit/UncountedLambdaCapturesChecker.cpp |  2 +
 ...mbda-captures-decl-protects-this-crash.cpp | 38 +++++++++++++++++++
 2 files changed, 40 insertions(+)
 create mode 100644 clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp

diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
index 4ffdac5ca4873..aee43bdd983a0 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
@@ -267,6 +267,8 @@ class UncountedLambdaCapturesChecker
             auto OpCode = OpCE->getOperator();
             if (OpCode == OO_Star || OpCode == OO_Amp) {
               auto *Callee = OpCE->getDirectCallee();
+              if (!Callee)
+                return false;
               auto clsName = safeGetName(Callee->getParent());
               if (!isRefType(clsName) || !OpCE->getNumArgs())
                 return false;
diff --git a/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp
new file mode 100644
index 0000000000000..0d25c599ffb3e
--- /dev/null
+++ b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp
@@ -0,0 +1,38 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=webkit.UncountedLambdaCapturesChecker -verify %s
+
+struct Foo {
+  int x;
+  int y;
+  Foo(int x, int y) : x(x) , y(y) { }
+};
+
+template <typename T>
+struct Baz {
+  void ref() const;
+  void deref() const;
+  Foo operator*();
+};
+
+inline Foo operator*(const Foo& a, const Foo& b);
+
+Baz<Foo> someFunction();
+template <typename CallbackType> void bar(CallbackType callback) {
+  auto baz = someFunction();
+  callback(baz);
+}
+
+struct Obj {
+  void ref() const;
+  void deref() const;
+
+  void foo(Foo foo) {
+    bar([this](auto baz) {
+      // expected-warning at -1{{Captured raw-pointer 'this' to ref-counted type or CheckedPtr-capable type is unsafe [webkit.UncountedLambdaCapturesChecker]}}
+      bar([this, foo = *baz](auto&&) {
+        // expected-warning at -1{{Captured raw-pointer 'this' to ref-counted type or CheckedPtr-capable type is unsafe [webkit.UncountedLambdaCapturesChecker]}}
+        someFunction();
+      });
+    });
+  }
+};
+

>From 2eb33277e1154965a21b3d7a26de00cb58505e1a Mon Sep 17 00:00:00 2001
From: Ryosuke Niwa <rniwa at webkit.org>
Date: Sat, 15 Feb 2025 02:49:06 -0800
Subject: [PATCH 2/2] Also fix an infinite loop in declProtectsThis.

---
 .../Checkers/WebKit/UncountedLambdaCapturesChecker.cpp       | 5 +++--
 .../uncounted-lambda-captures-decl-protects-this-crash.cpp   | 4 ++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
index aee43bdd983a0..9527993d0edeb 100644
--- a/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/WebKit/UncountedLambdaCapturesChecker.cpp
@@ -278,9 +278,10 @@ class UncountedLambdaCapturesChecker
           }
           if (auto *UO = dyn_cast<UnaryOperator>(Arg)) {
             auto OpCode = UO->getOpcode();
-            if (OpCode == UO_Deref || OpCode == UO_AddrOf)
+            if (OpCode == UO_Deref || OpCode == UO_AddrOf) {
               Arg = UO->getSubExpr()->IgnoreParenCasts();
-            continue;
+              continue;
+            }
           }
           break;
         } while (Arg);
diff --git a/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp
index 0d25c599ffb3e..840433db5133a 100644
--- a/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp
+++ b/clang/test/Analysis/Checkers/WebKit/uncounted-lambda-captures-decl-protects-this-crash.cpp
@@ -11,6 +11,7 @@ struct Baz {
   void ref() const;
   void deref() const;
   Foo operator*();
+  bool operator!();
 };
 
 inline Foo operator*(const Foo& a, const Foo& b);
@@ -28,11 +29,10 @@ struct Obj {
   void foo(Foo foo) {
     bar([this](auto baz) {
       // expected-warning at -1{{Captured raw-pointer 'this' to ref-counted type or CheckedPtr-capable type is unsafe [webkit.UncountedLambdaCapturesChecker]}}
-      bar([this, foo = *baz](auto&&) {
+      bar([this, foo = *baz, foo2 = !baz](auto&&) {
         // expected-warning at -1{{Captured raw-pointer 'this' to ref-counted type or CheckedPtr-capable type is unsafe [webkit.UncountedLambdaCapturesChecker]}}
         someFunction();
       });
     });
   }
 };
-