[clang] [clang-format] Fix crash in TokenAnnotator (PR #82349)

[Emilia Kond via cfe-commits]

https://github.com/rymiel updated https://github.com/llvm/llvm-project/pull/82349

>From 25ca98534f0d5dbd96ff74c802528171787ced45 Mon Sep 17 00:00:00 2001
From: Emilia Kond <emilia at rymiel.space>
Date: Tue, 20 Feb 2024 14:11:33 +0200
Subject: [PATCH 1/2] [clang-format] Fix crash in TokenAnnotator

The while loop on line 3814 can cause a segmentation fault getting the
Next field on a nullptr. This is because further down, on line 3823,
there is another for loop, which assigns Tok to Tok->Next in its
initializer. This for loop has a condition to check if the result of that
isn't null. If it is, the loop is skipped and we drop back out to the
outer loop, except, now Tok is null, and we try to dereference it without
checking first.

This patch adds a defensive check that returns if Tok->Next is null
before we make it to the second for loop.

Fixes https://github.com/llvm/llvm-project/issues/82328
---
 clang/lib/Format/TokenAnnotator.cpp   | 2 +-
 clang/unittests/Format/FormatTest.cpp | 3 +++
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index ec7b7f4dbe3470..a38ba8762f8505 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -3817,7 +3817,7 @@ void TokenAnnotator::calculateFormattingInformation(AnnotatedLine &Line) const {
         do {
           Tok = Tok->Next;
         } while (Tok && Tok->isNot(TT_OverloadedOperatorLParen));
-        if (!Tok)
+        if (!Tok || !Tok->Next)
           break;
         const auto *LeftParen = Tok;
         for (Tok = Tok->Next; Tok && Tok != LeftParen->MatchingParen;
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 24f62af8ddcb87..3a3c88f609af7a 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -13503,6 +13503,9 @@ TEST_F(FormatTest, IncorrectCodeUnbalancedBraces) {
   verifyFormat("{");
   verifyFormat("#})");
   verifyNoCrash("(/**/[:!] ?[).");
+  verifyNoCrash("struct X{"
+                "  operator iunt("
+                "};");
 }
 
 TEST_F(FormatTest, IncorrectUnbalancedBracesInMacrosWithUnicode) {

>From e5f5e64a5765d23c5b88e05d4f9b6d46bbbe5abd Mon Sep 17 00:00:00 2001
From: Emilia Kond <emilia at rymiel.space>
Date: Thu, 22 Feb 2024 14:55:16 +0200
Subject: [PATCH 2/2] Apply suggestions from code review

Co-authored-by: Owen Pan <owenpiano at gmail.com>
---
 clang/lib/Format/TokenAnnotator.cpp   | 2 +-
 clang/unittests/Format/FormatTest.cpp | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/clang/lib/Format/TokenAnnotator.cpp b/clang/lib/Format/TokenAnnotator.cpp
index a38ba8762f8505..a60d6ae197a24e 100644
--- a/clang/lib/Format/TokenAnnotator.cpp
+++ b/clang/lib/Format/TokenAnnotator.cpp
@@ -3817,7 +3817,7 @@ void TokenAnnotator::calculateFormattingInformation(AnnotatedLine &Line) const {
         do {
           Tok = Tok->Next;
         } while (Tok && Tok->isNot(TT_OverloadedOperatorLParen));
-        if (!Tok || !Tok->Next)
+        if (!Tok || !Tok->MatchingParen)
           break;
         const auto *LeftParen = Tok;
         for (Tok = Tok->Next; Tok && Tok != LeftParen->MatchingParen;
diff --git a/clang/unittests/Format/FormatTest.cpp b/clang/unittests/Format/FormatTest.cpp
index 3a3c88f609af7a..863d9c80d7ee6c 100644
--- a/clang/unittests/Format/FormatTest.cpp
+++ b/clang/unittests/Format/FormatTest.cpp
@@ -13503,8 +13503,8 @@ TEST_F(FormatTest, IncorrectCodeUnbalancedBraces) {
   verifyFormat("{");
   verifyFormat("#})");
   verifyNoCrash("(/**/[:!] ?[).");
-  verifyNoCrash("struct X{"
-                "  operator iunt("
+  verifyNoCrash("struct X {\n"
+                "  operator iunt(\n"
                 "};");
 }