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[analyzer] Relax assertion in BugReporterVisitors.cpp isInitializationOfVar (#125044)

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If we see a variable declaration (aka. DeclStmt), and the VarRegion it
declared doesn't have Stack memspace, we assumed that it must be a local
static variable.
However, the declared variable may be an extern declaration of a global.

In this patch, let's admit that local extern declarations are a thing.

For the sake of completeness, I also added one more test for
thread_locals - which are implicitly considered statics btw. (the
`isStaticLocal()` correctly also considers thread locals as local
statics).

Fixes #124975
This commit is contained in:
Balazs Benics
2025-01-30 12:48:09 +01:00
committed by GitHub
parent b68b4f64a2
commit 025541dded
2 changed files with 39 additions and 1 deletions
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5
clang/lib/StaticAnalyzer/Core/BugReporterVisitors.cpp
View File

@@ -1198,7 +1198,10 @@ static bool isInitializationOfVar(const ExplodedNode *N, const VarRegion *VR) {
// If we ever directly evaluate global DeclStmts, this assertion will be
// invalid, but this still seems preferable to silently accepting an
// initialization that may be for a path-sensitive variable.
assert(VR->getDecl()->isStaticLocal() && "non-static stackless VarRegion");
[[maybe_unused]] bool IsLocalStaticOrLocalExtern =
VR->getDecl()->isStaticLocal() || VR->getDecl()->isLocalExternDecl();
assert(IsLocalStaticOrLocalExtern &&
"Declared a variable on the stack without Stack memspace?");
return true;
}

35
clang/test/Analysis/null-deref-path-notes.cpp
View File

@@ -23,3 +23,38 @@ void c::f(B &g, int &i) {
f(h, b); // expected-note{{Calling 'c::f'}}
}
}
namespace GH124975 {
void no_crash_in_br_visitors(int *p) {
if (p) {}
// expected-note@-1 {{Assuming 'p' is null}}
// expected-note@-2 {{Taking false branch}}
extern bool ExternLocalCoin;
// expected-note@+2 {{Assuming 'ExternLocalCoin' is false}}
// expected-note@+1 {{Taking false branch}}
if (ExternLocalCoin)
return;
*p = 4;
// expected-warning@-1 {{Dereference of null pointer (loaded from variable 'p')}}
// expected-note@-2 {{Dereference of null pointer (loaded from variable 'p')}}
}
// Thread local variables are implicitly static, so let's test them too.
void thread_local_alternative(int *p) {
if (p) {}
// expected-note@-1 {{Assuming 'p' is null}}
// expected-note@-2 {{Taking false branch}}
thread_local bool ThreadLocalCoin;
// expected-note@+2 {{'ThreadLocalCoin' is false}}
// expected-note@+1 {{Taking false branch}}
if (ThreadLocalCoin)
return;
*p = 4;
// expected-warning@-1 {{Dereference of null pointer (loaded from variable 'p')}}
// expected-note@-2 {{Dereference of null pointer (loaded from variable 'p')}}
}
} // namespace GH124975