https://github.com/andyames-a11y created
https://github.com/llvm/llvm-project/pull/210649
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
>From 6b8cc1fa8411fa1a7f625174d63cc0f942284efe Mon Sep 17 00:00:00 2001
From: Andy Ames <[email protected]>
Date: Sun, 19 Jul 2026 21:59:48 -0700
Subject: [PATCH] [analyzer] Fix crash in RegionStoreManager::bindArray from
constructor array-to-pointer decay
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
---
clang/lib/StaticAnalyzer/Core/ExprEngine.cpp | 2 +-
clang/lib/StaticAnalyzer/Core/RegionStore.cpp | 8 ++++-
clang/test/Analysis/initializer.cpp | 8 ++---
clang/test/Analysis/issue-210183.cpp | 34 +++++++++++++++++++
4 files changed, 45 insertions(+), 7 deletions(-)
create mode 100644 clang/test/Analysis/issue-210183.cpp
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
+}
_______________________________________________
cfe-commits mailing list
[email protected]
https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
