[clang] [analyzer] Fix stores through label locations (PR #89265)

[via cfe-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-clang-static-analyzer-1

Author: Balazs Benics (steakhal)

<details>
<summary>Changes</summary>

Interestingly, this case crashed from the very beginning of the project, at least starting by clang-3.

As a "fix" I just do the same thing as we do for concrete integers. It might not be the best we could do, but arguably, it's still better than crashing.

Fixes #<!-- -->89185

---
Full diff: https://github.com/llvm/llvm-project/pull/89265.diff


3 Files Affected:

- (modified) clang/docs/ReleaseNotes.rst (+2) 
- (modified) clang/lib/StaticAnalyzer/Core/RegionStore.cpp (+4-3) 
- (added) clang/test/Analysis/gh-issue-89185.c (+14) 


``````````diff
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 6099f8ab02f443..1d98330d2e4a00 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -681,6 +681,8 @@ Static Analyzer
 - Support C++23 static operator calls. (#GH84972)
 - Fixed a crash in ``security.cert.env.InvalidPtr`` checker when accidentally
   matched user-defined ``strerror`` and similar library functions. (GH#88181)
+- Fixed a crash when storing through an address that refers to the address of
+  a label. (GH#89185)
 
 New features
 ^^^^^^^^^^^^
diff --git a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
index 755a8c4b22fd9e..2379db9fdb0576 100644
--- a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -2358,11 +2358,12 @@ StoreRef RegionStoreManager::killBinding(Store ST, Loc L) {
 
 RegionBindingsRef
 RegionStoreManager::bind(RegionBindingsConstRef B, Loc L, SVal V) {
-  if (L.getAs<loc::ConcreteInt>())
+  // We only care about region locations.
+  auto MemRegVal = L.getAs<loc::MemRegionVal>();
+  if (!MemRegVal.has_value())
     return B;
 
-  // If we get here, the location should be a region.
-  const MemRegion *R = L.castAs<loc::MemRegionVal>().getRegion();
+  const MemRegion *R = MemRegVal->getRegion();
 
   // Check if the region is a struct region.
   if (const TypedValueRegion* TR = dyn_cast<TypedValueRegion>(R)) {
diff --git a/clang/test/Analysis/gh-issue-89185.c b/clang/test/Analysis/gh-issue-89185.c
new file mode 100644
index 00000000000000..8a907f198a5fd5
--- /dev/null
+++ b/clang/test/Analysis/gh-issue-89185.c
@@ -0,0 +1,14 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection -verify %s
+
+void clang_analyzer_dump(char);
+void clang_analyzer_dump_ptr(char*);
+
+// https://github.com/llvm/llvm-project/issues/89185
+void binding_to_label_loc() {
+  char *b = &&MyLabel;
+MyLabel:
+  *b = 0; // no-crash
+  clang_analyzer_dump_ptr(b); // expected-warning {{&&MyLabel}}
+  clang_analyzer_dump(*b); // expected-warning {{Unknown}}
+  // FIXME: We should never reach here, as storing to a label is invalid.
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/89265