[clang] [-Wunsafe-buffer-usage] Suppress warning for multi-dimensional constant arrays (PR #118249)
Malavika Samak via cfe-commits
cfe-commits at lists.llvm.org
Fri Dec 6 21:35:09 PST 2024
https://github.com/malavikasamak updated https://github.com/llvm/llvm-project/pull/118249
>From e1eadf464509ab74ff4f097f92e7140f43c61262 Mon Sep 17 00:00:00 2001
From: MalavikaSamak <malavika2 at apple.com>
Date: Fri, 29 Nov 2024 14:53:37 +0530
Subject: [PATCH] [-Wunsafe-buffer-usage] Suppress warning for
multi-dimensional constant arrays
Do not warn about unsafe buffer access, when multi-dimensional constant arrays
are accessed and their indices are within the bounds of the buffer. Warning in
such cases would be a false positive. Such a suppression already exists for 1-d
arrays and it is now extended to multi-dimensional arrays.
(rdar://137926311)
(rdar://140320139)
---
clang/lib/Analysis/UnsafeBufferUsage.cpp | 44 +++++++------------
.../warn-unsafe-buffer-usage-array.cpp | 40 +++++++++++++++++
.../warn-unsafe-buffer-usage-field-attr.cpp | 1 -
...e-buffer-usage-fixits-parm-unsupported.cpp | 2 +-
.../test/SemaCXX/warn-unsafe-buffer-usage.cpp | 39 +++++++++-------
5 files changed, 82 insertions(+), 44 deletions(-)
diff --git a/clang/lib/Analysis/UnsafeBufferUsage.cpp b/clang/lib/Analysis/UnsafeBufferUsage.cpp
index 5f36ffa926b269..c3f580ec42eba3 100644
--- a/clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ b/clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -433,37 +433,27 @@ AST_MATCHER(ArraySubscriptExpr, isSafeArraySubscript) {
// already duplicated
// - call both from Sema and from here
- const auto *BaseDRE =
- dyn_cast<DeclRefExpr>(Node.getBase()->IgnoreParenImpCasts());
- const auto *SLiteral =
- dyn_cast<StringLiteral>(Node.getBase()->IgnoreParenImpCasts());
- uint64_t size;
-
- if (!BaseDRE && !SLiteral)
- return false;
-
- if (BaseDRE) {
- if (!BaseDRE->getDecl())
- return false;
- const auto *CATy = Finder->getASTContext().getAsConstantArrayType(
- BaseDRE->getDecl()->getType());
- if (!CATy) {
+ uint64_t limit;
+ if (const auto *CATy =
+ dyn_cast<ConstantArrayType>(Node.getBase()
+ ->IgnoreParenImpCasts()
+ ->getType()
+ ->getUnqualifiedDesugaredType())) {
+ limit = CATy->getLimitedSize();
+ } else if (const auto *SLiteral = dyn_cast<StringLiteral>(
+ Node.getBase()->IgnoreParenImpCasts())) {
+ limit = SLiteral->getLength() + 1;
+ } else {
return false;
}
- size = CATy->getLimitedSize();
- } else if (SLiteral) {
- size = SLiteral->getLength() + 1;
- }
- if (const auto *IdxLit = dyn_cast<IntegerLiteral>(Node.getIdx())) {
- const APInt ArrIdx = IdxLit->getValue();
- // FIXME: ArrIdx.isNegative() we could immediately emit an error as that's a
- // bug
- if (ArrIdx.isNonNegative() && ArrIdx.getLimitedValue() < size)
+ if (const auto *IdxLit = dyn_cast<IntegerLiteral>(Node.getIdx())) {
+ const APInt ArrIdx = IdxLit->getValue();
+ if (!ArrIdx.isNonNegative() || ArrIdx.getLimitedValue() >= limit)
+ return false;
return true;
- }
-
- return false;
+ }
+ return false;
}
AST_MATCHER_P(CallExpr, hasNumArgs, unsigned, Num) {
diff --git a/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp b/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
index c6c93a27e4b969..7dd6c83dbba2a8 100644
--- a/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
+++ b/clang/test/SemaCXX/warn-unsafe-buffer-usage-array.cpp
@@ -52,3 +52,43 @@ void constant_id_string(unsigned idx) {
unsafe_char = ""[1]; //expected-warning{{unsafe buffer access}}
unsafe_char = ""[idx]; //expected-warning{{unsafe buffer access}}
}
+
+typedef float Float4x4[4][4];
+
+// expected-warning at +1 {{'matrix' is an unsafe buffer that does not perform bounds checks}}
+float two_dimension_array(Float4x4& matrix, unsigned idx) {
+ // expected-warning at +1{{unsafe buffer access}}
+ float a = matrix[0][4];
+
+ a = matrix[0][3];
+
+ // expected-note at +1{{used in buffer access here}}
+ a = matrix[4][0];
+
+ a = matrix[idx][0]; // expected-note{{used in buffer access here}}
+
+ a = matrix[0][idx]; //expected-warning{{unsafe buffer access}}
+
+ a = matrix[idx][idx]; //expected-warning{{unsafe buffer access}} // expected-note{{used in buffer access here}}
+
+ return matrix[1][1];
+}
+
+typedef float Float2x3x4[2][3][4];
+float multi_dimension_array(Float2x3x4& matrix) {
+ float *f = matrix[0][2];
+ return matrix[1][2][3];
+}
+
+char array_strings[][11] = {
+ "Apple", "Banana", "Cherry", "Date", "Elderberry"
+};
+
+char array_string[] = "123456";
+
+char access_strings() {
+ char c = array_strings[0][4];
+ c = array_strings[3][10];
+ c = array_string[5];
+ return c;
+}
diff --git a/clang/test/SemaCXX/warn-unsafe-buffer-usage-field-attr.cpp b/clang/test/SemaCXX/warn-unsafe-buffer-usage-field-attr.cpp
index 0ba605475925b9..1636c948da075a 100644
--- a/clang/test/SemaCXX/warn-unsafe-buffer-usage-field-attr.cpp
+++ b/clang/test/SemaCXX/warn-unsafe-buffer-usage-field-attr.cpp
@@ -96,7 +96,6 @@ void test_attribute_multiple_fields (D d) {
int v = d.buf[0]; //expected-warning{{field 'buf' prone to unsafe buffer manipulation}}
- //expected-warning at +1{{unsafe buffer access}}
v = d.buf[5]; //expected-warning{{field 'buf' prone to unsafe buffer manipulation}}
}
diff --git a/clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-parm-unsupported.cpp b/clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-parm-unsupported.cpp
index 71350098613d19..0c80da63f82912 100644
--- a/clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-parm-unsupported.cpp
+++ b/clang/test/SemaCXX/warn-unsafe-buffer-usage-fixits-parm-unsupported.cpp
@@ -118,7 +118,7 @@ void isArrayDecayToPointerUPC(int a[][10], int (*b)[10]) {
// expected-warning at -2{{'b' is an unsafe pointer used for buffer access}}
int tmp;
- tmp = a[5][5] + b[5][5]; // expected-warning2{{unsafe buffer access}} expected-note2{{used in buffer access here}}
+ tmp = a[5][5] + b[5][5]; // expected-note2{{used in buffer access here}}
}
// parameter having default values:
diff --git a/clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp b/clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
index 642db0e9d3c632..41d38ada48788c 100644
--- a/clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
+++ b/clang/test/SemaCXX/warn-unsafe-buffer-usage.cpp
@@ -109,7 +109,6 @@ void testQualifiedParameters(const int * p, const int * const q, const int a[10]
q[1], 1[q], q[-1], // expected-note3{{used in buffer access here}}
a[1], // expected-note{{used in buffer access here}} `a` is of pointer type
b[1][2] // expected-note{{used in buffer access here}} `b[1]` is of array type
- // expected-warning at -1{{unsafe buffer access}}
);
}
@@ -128,29 +127,41 @@ T_t funRetT();
T_t * funRetTStar();
void testStructMembers(struct T * sp, struct T s, T_t * sp2, T_t s2) {
- foo(sp->a[1], // expected-warning{{unsafe buffer access}}
+ foo(sp->a[1],
sp->b[1], // expected-warning{{unsafe buffer access}}
- sp->c.a[1], // expected-warning{{unsafe buffer access}}
+ sp->c.a[1],
sp->c.b[1], // expected-warning{{unsafe buffer access}}
- s.a[1], // expected-warning{{unsafe buffer access}}
+ s.a[1],
s.b[1], // expected-warning{{unsafe buffer access}}
- s.c.a[1], // expected-warning{{unsafe buffer access}}
+ s.c.a[1],
s.c.b[1], // expected-warning{{unsafe buffer access}}
- sp2->a[1], // expected-warning{{unsafe buffer access}}
+ sp2->a[1],
sp2->b[1], // expected-warning{{unsafe buffer access}}
- sp2->c.a[1], // expected-warning{{unsafe buffer access}}
+ sp2->c.a[1],
sp2->c.b[1], // expected-warning{{unsafe buffer access}}
- s2.a[1], // expected-warning{{unsafe buffer access}}
+ s2.a[1],
s2.b[1], // expected-warning{{unsafe buffer access}}
- s2.c.a[1], // expected-warning{{unsafe buffer access}}
+ s2.c.a[1],
s2.c.b[1], // expected-warning{{unsafe buffer access}}
- funRetT().a[1], // expected-warning{{unsafe buffer access}}
+ funRetT().a[1],
funRetT().b[1], // expected-warning{{unsafe buffer access}}
- funRetTStar()->a[1], // expected-warning{{unsafe buffer access}}
+ funRetTStar()->a[1],
funRetTStar()->b[1] // expected-warning{{unsafe buffer access}}
);
}
+union Foo {
+ bool b;
+ int arr[10];
+};
+
+int testUnionMembers(Foo f) {
+ int a = f.arr[0];
+ a = f.arr[5];
+ a = f.arr[10]; // expected-warning{{unsafe buffer access}}
+ return a;
+}
+
int garray[10]; // expected-warning{{'garray' is an unsafe buffer that does not perform bounds checks}}
int * gp = garray; // expected-warning{{'gp' is an unsafe pointer used for buffer access}}
int gvar = gp[1]; // FIXME: file scope unsafe buffer access is not warned
@@ -213,7 +224,6 @@ void testTypedefs(T_ptr_t p) {
// expected-warning at -1{{'p' is an unsafe pointer used for buffer access}}
foo(p[1], // expected-note{{used in buffer access here}}
p[1].a[1], // expected-note{{used in buffer access here}}
- // expected-warning at -1{{unsafe buffer access}}
p[1].b[1] // expected-note{{used in buffer access here}}
// expected-warning at -1{{unsafe buffer access}}
);
@@ -223,10 +233,9 @@ template<typename T, int N> T f(T t, T * pt, T a[N], T (&b)[N]) {
// expected-warning at -1{{'t' is an unsafe pointer used for buffer access}}
// expected-warning at -2{{'pt' is an unsafe pointer used for buffer access}}
// expected-warning at -3{{'a' is an unsafe pointer used for buffer access}}
- // expected-warning at -4{{'b' is an unsafe buffer that does not perform bounds checks}}
foo(pt[1], // expected-note{{used in buffer access here}}
a[1], // expected-note{{used in buffer access here}}
- b[1]); // expected-note{{used in buffer access here}}
+ b[1]);
return &t[1]; // expected-note{{used in buffer access here}}
}
@@ -376,7 +385,7 @@ int testArrayAccesses(int n, int idx) {
typedef int A[3];
const A tArr = {4, 5, 6};
foo(tArr[0], tArr[1]);
- return cArr[0][1]; // expected-warning{{unsafe buffer access}}
+ return cArr[0][1];
}
void testArrayPtrArithmetic(int x[]) { // expected-warning{{'x' is an unsafe pointer used for buffer access}}
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