llvmorg-github-actions[bot] wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang-static-analyzer-1
Author: Andy Ames (andyames-a11y)
<details>
<summary>Changes</summary>
ProcessInitializer() strips implicit casts from a CXXCtorInitializer's init
expression via IgnoreImplicit(), then decides whether to treat the initializer
as a direct array-to-array member copy by checking
Init->getType()->isArrayType(). For a pointer member initialized via
array-to-pointer decay of a reference-to-array constructor parameter (e.g.
`Foo(T (&arr)[N]) : ptr_(arr) {}`), IgnoreImplicit() strips the
ArrayToPointerDecay cast, exposing the underlying array-typed expression, so
this check misfires even though the field itself is a pointer, not an array.
That branch fetches the raw region address of the whole array, bypassing the
normal decay logic (which produces an ElementRegion), so the pointer member
ends up holding the address of the whole array typed as the array itself,
instead of an ElementRegion at index 0.
Later, dereferencing and storing through that mistyped pointer routes into
RegionStoreManager::bindArray() (instead of bindScalar()), which
unconditionally casts its Init value to nonloc::CompoundVal, asserting in a
debug build and segfaulting in a release build when Init is anything else, e.g.
a nonloc::LocAsInteger produced by round-tripping a pointer through an integer
type.
Fix the actual bug by checking the field's type instead of the initializer
expression's type. Also generalize bindArray()'s existing guard (added by #<!--
-->178923 for issue #<!-- -->178797) from an enumeration of specific SVal kinds
to the same exhaustive
`!isa<nonloc::CompoundVal>()` check already used by its siblings
bindStruct() and bindVector(), so it doesn't need to be extended again every
time a new SVal kind reaches this path -- this is what actually catches our
case (nonloc::LocAsInteger), which the prior enumeration didn't cover.
This is the same underlying bug behind #<!-- -->147686 (fixed by #<!--
-->153177, which its own author noted was "more of a workaround") and #<!--
-->178797 (fixed by #<!-- -->178923); both those fixes patched symptoms at
bindArray() without addressing the ProcessInitializer() root cause. Fixing the
root cause also resolves two FIXME-annotated precision gaps in
clang/test/Analysis/initializer.cpp's gh147686 regression test.
Fixes #<!-- -->210183
---
Full diff: https://github.com/llvm/llvm-project/pull/210649.diff
4 Files Affected:
- (modified) clang/lib/StaticAnalyzer/Core/ExprEngine.cpp (+1-1)
- (modified) clang/lib/StaticAnalyzer/Core/RegionStore.cpp (+7-1)
- (modified) clang/test/Analysis/initializer.cpp (+3-5)
- (added) clang/test/Analysis/issue-210183.cpp (+34)
``````````diff
diff --git a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 2d86c779ba850..678b07ebba1b0 100644
--- a/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/clang/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -1196,7 +1196,7 @@ void ExprEngine::ProcessInitializer(const CFGInitializer
CFGInit,
}
SVal InitVal;
- if (Init->getType()->isArrayType()) {
+ if (Field->getType()->isArrayType()) {
// Handle arrays of trivial type. We can represent this with a
// primitive load/copy from the base array region.
const ArraySubscriptExpr *ASE;
diff --git a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
index 0f7e03ce50858..9ddcf9aebee6f 100644
--- a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -2726,7 +2726,13 @@
RegionStoreManager::bindArray(LimitedRegionBindingsConstRef B,
return bindAggregate(B, R, Init);
}
- if (isa<nonloc::SymbolVal, UnknownVal, UndefinedVal>(Init))
+ // We may get non-CompoundVal accidentally due to imprecise cast logic or
+ // that we are binding a genuinely symbolic/unknown/undefined array value.
+ // Preserve Init as a default binding rather than lossily converting to
+ // UnknownVal(), and handle every non-CompoundVal case exhaustively (like
+ // bindStruct()/bindVector() do) rather than enumerating specific SVal
+ // kinds one at a time.
+ if (!isa<nonloc::CompoundVal>(Init))
return bindAggregate(B, R, Init);
// Remaining case: explicit compound values.
diff --git a/clang/test/Analysis/initializer.cpp
b/clang/test/Analysis/initializer.cpp
index 88758f7c3ac1d..dd0c91b7ead61 100644
--- a/clang/test/Analysis/initializer.cpp
+++ b/clang/test/Analysis/initializer.cpp
@@ -628,8 +628,7 @@ struct A {
void test1() {
A a;
clang_analyzer_eval(a.m_buf[0] == 0); // expected-warning{{TRUE}}
- // FIXME The next eval should result in TRUE.
- clang_analyzer_eval(*a.m_ptr == 0); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval(*a.m_ptr == 0); // expected-warning{{TRUE}}
}
void test2() {
@@ -646,9 +645,8 @@ void test3() {
void test3Bis(char arg) {
A a(arg);
- // FIXME This test should behave like test3.
- clang_analyzer_eval(a.m_buf[0] == arg); // expected-warning{{FALSE}} //
expected-warning{{TRUE}}
- clang_analyzer_eval(*a.m_ptr == arg); // expected-warning{{UNKNOWN}}
+ clang_analyzer_eval(a.m_buf[0] == arg); // expected-warning{{TRUE}}
+ clang_analyzer_eval(*a.m_ptr == arg); // expected-warning{{TRUE}}
}
void test4(char arg) {
diff --git a/clang/test/Analysis/issue-210183.cpp
b/clang/test/Analysis/issue-210183.cpp
new file mode 100644
index 0000000000000..ba443aa82ba53
--- /dev/null
+++ b/clang/test/Analysis/issue-210183.cpp
@@ -0,0 +1,34 @@
+// RUN: %clang_analyze_cc1 -analyzer-checker=core,debug.ExprInspection
-std=c++17 -verify %s
+
+// https://github.com/llvm/llvm-project/issues/210183
+//
+// A pointer member initialized via array-to-pointer decay of a
+// reference-to-array constructor parameter used to be modeled as the
+// address of the whole array (instead of its first element). Dereferencing
+// and storing through that mistyped pointer then reached
+// RegionStoreManager::bindArray() with a scalar Init value, crashing on an
+// unchecked castAs<nonloc::CompoundVal>().
+
+template <class T> void clang_analyzer_dump(T);
+
+template <class T> struct Span {
+ template <int N>
+ Span(T (&arr)[N]) : ptr_(arr) {}
+ T *data() { return ptr_; }
+ T *ptr_;
+};
+
+char *ptr();
+char buffer[10];
+
+void test() {
+ char *p = Span<char>(buffer).data();
+
+ // p and buffer must resolve to the same address: the first element of
+ // buffer, not the whole array.
+ clang_analyzer_dump(buffer); // expected-warning{{&Element{buffer,0
S64b,char}}}
+ clang_analyzer_dump(p); // expected-warning{{&Element{buffer,0
S64b,char}}}
+
+ int v = (int)(long)ptr();
+ *p = v; // no-crash
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/210649
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