https://github.com/necto created
https://github.com/llvm/llvm-project/pull/106240
If a mutex interface is split in inheritance chain, e.g. struct mutex has
`unlock` and inherits `lock` from __mutex_base then calls m.lock() and
m.unlock() have different "this" targets: m and the __mutex_base of m, which
used to confuse the `ActiveCritSections` list.
Taking base region canonicalizes the region used to identify a critical section
and enables search in ActiveCritSections list regardless of which class the
callee is the member of.
This possibly fixes #104241
CPP-5541
>From 0c86e46516466f9513652a04ba87aa2a018ff6b8 Mon Sep 17 00:00:00 2001
From: Arseniy Zaostrovnykh <necto...@gmail.com>
Date: Tue, 27 Aug 2024 17:52:25 +0200
Subject: [PATCH] [analyzer] Fix false positive for mutexes inheriting
mutex_base
If a mutex interface is split in inheritance chain, e.g. struct mutex
has `unlock` and inherits `lock` from __mutex_base then calls m.lock()
and m.unlock() have different "this" targets: m and the __mutex_base of
m, which used to confuse the `ActiveCritSections` list.
Taking base region canonicalizes the region used to identify a critical
section and enables search in ActiveCritSections list regardless of
which class the callee is the member of.
This possibly fixes #104241
CPP-5541
---
.../Checkers/BlockInCriticalSectionChecker.cpp | 6 ++++--
.../Analysis/block-in-critical-section-inheritance.cpp | 10 ++++++++++
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git
a/clang/lib/StaticAnalyzer/Checkers/BlockInCriticalSectionChecker.cpp
b/clang/lib/StaticAnalyzer/Checkers/BlockInCriticalSectionChecker.cpp
index 4cd2f2802f30cd..52ff639c6b8022 100644
--- a/clang/lib/StaticAnalyzer/Checkers/BlockInCriticalSectionChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/BlockInCriticalSectionChecker.cpp
@@ -245,8 +245,10 @@ static const MemRegion *getRegion(const CallEvent &Call,
const MutexDescriptor &Descriptor,
bool IsLock) {
return std::visit(
- [&Call, IsLock](auto &&Descriptor) {
- return Descriptor.getRegion(Call, IsLock);
+ [&Call, IsLock](auto &Descr) -> const MemRegion * {
+ if (const MemRegion *Reg = Descr.getRegion(Call, IsLock))
+ return Reg->getBaseRegion();
+ return nullptr;
},
Descriptor);
}
diff --git a/clang/test/Analysis/block-in-critical-section-inheritance.cpp
b/clang/test/Analysis/block-in-critical-section-inheritance.cpp
index db20df8c60a5c9..c60ba2632cee25 100644
--- a/clang/test/Analysis/block-in-critical-section-inheritance.cpp
+++ b/clang/test/Analysis/block-in-critical-section-inheritance.cpp
@@ -29,3 +29,13 @@ void gh_99628() {
// expected-note@-2 {{Call to blocking function 'sleep' inside of critical
section}}
m.unlock();
}
+
+void no_false_positive_gh_104241() {
+ std::mutex m;
+ m.lock();
+ // If inheritance not handled properly, this unlock might not match the lock
+ // above because technically they act on different memory regions:
+ // __mutex_base and mutex.
+ m.unlock();
+ sleep(10); // no-warning
+}
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