[clang] [clang][analyzer] Fix argument invalidations in StreamChecker. (PR #79470)
Balázs Kéri via cfe-commits
cfe-commits at lists.llvm.org
Thu Feb 22 23:59:35 PST 2024
https://github.com/balazske updated https://github.com/llvm/llvm-project/pull/79470
>From 70eeae8170a782b93b546b81ac913e1b8eacd28e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bal=C3=A1zs=20K=C3=A9ri?= <balazs.keri at ericsson.com>
Date: Thu, 22 Feb 2024 10:18:06 +0100
Subject: [PATCH 1/2] [clang][analyzer] Fix argument invalidations in
StreamChecker.
Specific arguments passed to stream handling functions are changed by the function,
this means these should be invalidated ("escaped") by the analyzer.
This change adds the argument invalidation (in specific cases) to the checker.
---
.../StaticAnalyzer/Checkers/StreamChecker.cpp | 39 ++++++++++++++++++-
1 file changed, 38 insertions(+), 1 deletion(-)
diff --git a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
index a070f451694a3b..65bdc4cac30940 100644
--- a/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/StreamChecker.cpp
@@ -21,6 +21,7 @@
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
#include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
+#include "llvm/ADT/Sequence.h"
#include <functional>
#include <optional>
@@ -629,6 +630,21 @@ const ExplodedNode *StreamChecker::getAcquisitionSite(const ExplodedNode *N,
return nullptr;
}
+static ProgramStateRef escapeArgs(ProgramStateRef State, CheckerContext &C,
+ const CallEvent &Call,
+ ArrayRef<unsigned int> EscapingArgs) {
+ const auto *CE = Call.getOriginExpr();
+
+ SmallVector<SVal> EscapingVals;
+ EscapingVals.reserve(EscapingArgs.size());
+ for (auto EscArgIdx : EscapingArgs)
+ EscapingVals.push_back(Call.getArgSVal(EscArgIdx));
+ State = State->invalidateRegions(EscapingVals, CE, C.blockCount(),
+ C.getLocationContext(),
+ /*CausesPointerEscape=*/false);
+ return State;
+}
+
//===----------------------------------------------------------------------===//
// Methods of StreamChecker.
//===----------------------------------------------------------------------===//
@@ -819,6 +835,11 @@ void StreamChecker::evalFreadFwrite(const FnDescription *Desc,
return;
}
+ // At read, invalidate the buffer in any case of error or success,
+ // except if EOF was already present.
+ if (IsFread && !E.isStreamEof())
+ State = escapeArgs(State, C, Call, {0});
+
// Generate a transition for the success state.
// If we know the state to be FEOF at fread, do not add a success state.
if (!IsFread || !E.isStreamEof()) {
@@ -863,6 +884,9 @@ void StreamChecker::evalFgetx(const FnDescription *Desc, const CallEvent &Call,
return;
if (!E.isStreamEof()) {
+ // If there was already EOF, assume that read buffer is not changed.
+ // Otherwise it may change at success or failure.
+ State = escapeArgs(State, C, Call, {0});
if (SingleChar) {
// Generate a transition for the success state of `fgetc`.
NonLoc RetVal = makeRetVal(C, E.CE).castAs<NonLoc>();
@@ -1011,6 +1035,14 @@ void StreamChecker::evalFscanf(const FnDescription *Desc, const CallEvent &Call,
State->BindExpr(E.CE, C.getLocationContext(), RetVal);
StateNotFailed =
E.assumeBinOpNN(StateNotFailed, BO_GE, RetVal, E.getZeroVal(Call));
+ if (!StateNotFailed)
+ return;
+
+ SmallVector<unsigned int> EscArgs;
+ for (auto EscArg : llvm::seq(2u, Call.getNumArgs()))
+ EscArgs.push_back(EscArg);
+ StateNotFailed = escapeArgs(StateNotFailed, C, Call, EscArgs);
+
if (StateNotFailed)
C.addTransition(StateNotFailed);
}
@@ -1073,8 +1105,12 @@ void StreamChecker::evalGetdelim(const FnDescription *Desc,
// return -1.
// If an error occurs, the function shall return -1 and set 'errno'.
- // Add transition for the successful state.
if (!E.isStreamEof()) {
+ // Escape buffer and size (may change by the call).
+ // May happen even at error (partial read?).
+ State = escapeArgs(State, C, Call, {0, 1});
+
+ // Add transition for the successful state.
NonLoc RetVal = makeRetVal(C, E.CE).castAs<NonLoc>();
ProgramStateRef StateNotFailed =
State->BindExpr(E.CE, C.getLocationContext(), RetVal);
@@ -1161,6 +1197,7 @@ void StreamChecker::evalFgetpos(const FnDescription *Desc,
ProgramStateRef StateNotFailed, StateFailed;
std::tie(StateFailed, StateNotFailed) = E.makeRetValAndAssumeDual(State, C);
+ StateNotFailed = escapeArgs(StateNotFailed, C, Call, {1});
// This function does not affect the stream state.
// Still we add success and failure state with the appropriate return value.
>From deb62b2e2694e8a45eca1c6001b8d90dfb1b1d7b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bal=C3=A1zs=20K=C3=A9ri?= <balazs.keri at ericsson.com>
Date: Fri, 23 Feb 2024 08:59:03 +0100
Subject: [PATCH 2/2] Add test file
---
clang/test/Analysis/stream-invalidate.c | 147 ++++++++++++++++++++++++
1 file changed, 147 insertions(+)
create mode 100644 clang/test/Analysis/stream-invalidate.c
diff --git a/clang/test/Analysis/stream-invalidate.c b/clang/test/Analysis/stream-invalidate.c
new file mode 100644
index 00000000000000..6745d11a2fe701
--- /dev/null
+++ b/clang/test/Analysis/stream-invalidate.c
@@ -0,0 +1,147 @@
+// RUN: %clang_analyze_cc1 -verify %s \
+// RUN: -analyzer-checker=core \
+// RUN: -analyzer-checker=alpha.unix.Stream \
+// RUN: -analyzer-checker=debug.ExprInspection
+
+#include "Inputs/system-header-simulator.h"
+
+void clang_analyzer_eval(int);
+void clang_analyzer_dump(int);
+
+void test_fread(void) {
+ FILE *F = fopen("file", "r+");
+ if (!F)
+ return;
+
+ char Buf[3] = {10, 10, 10};
+ fread(Buf, 1, 3, F);
+ // The check applies to success and failure.
+ clang_analyzer_dump(Buf[0]); // expected-warning {{conj_$}} Should not preserve the previous value, thus should not be 10.
+ clang_analyzer_dump(Buf[2]); // expected-warning {{conj_$}}
+ if (feof(F)) {
+ char Buf1[3] = {10, 10, 10};
+ fread(Buf1, 1, 3, F); // expected-warning {{is in EOF state}}
+ clang_analyzer_dump(Buf1[0]); // expected-warning {{10 S32b}}
+ clang_analyzer_dump(Buf1[2]); // expected-warning {{10 S32b}}
+ }
+
+ fclose(F);
+}
+
+void test_fwrite(void) {
+ FILE *F = fopen("file", "r+");
+ if (!F)
+ return;
+
+ char Buf[3] = {10, 10, 10};
+ fwrite(Buf, 1, 3, F);
+ // The check applies to success and failure.
+ clang_analyzer_dump(Buf[0]); // expected-warning {{10 S32b}}
+ clang_analyzer_dump(Buf[2]); // expected-warning {{10 S32b}}
+
+ fclose(F);
+}
+
+void test_fgets() {
+ FILE *F = tmpfile();
+ if (!F)
+ return;
+
+ char Buf[3] = {10, 10, 10};
+ fgets(Buf, 3, F);
+ // The check applies to success and failure.
+ clang_analyzer_dump(Buf[0]); // expected-warning {{conj_$}} Should not preserve the previous value, thus should not be 10.
+ clang_analyzer_dump(Buf[2]); // expected-warning {{conj_$}}
+ if (feof(F)) {
+ char Buf1[3] = {10, 10, 10};
+ fgets(Buf1, 3, F); // expected-warning {{is in EOF state}}
+ clang_analyzer_dump(Buf1[0]); // expected-warning {{10 S32b}}
+ clang_analyzer_dump(Buf1[2]); // expected-warning {{10 S32b}}
+ }
+
+ fclose(F);
+}
+
+void test_fputs() {
+ FILE *F = tmpfile();
+ if (!F)
+ return;
+
+ char *Buf = "aaa";
+ fputs(Buf, F);
+ // The check applies to success and failure.
+ clang_analyzer_dump(Buf[0]); // expected-warning {{97 S32b}}
+ clang_analyzer_dump(Buf[2]); // expected-warning {{97 S32b}}
+ clang_analyzer_dump(Buf[3]); // expected-warning {{0 S32b}}
+
+ fclose(F);
+}
+
+void test_fscanf() {
+ FILE *F = tmpfile();
+ if (!F)
+ return;
+
+ int a = 1;
+ unsigned b;
+ int Ret = fscanf(F, "%d %u", &a, &b);
+ if (Ret == 0) {
+ clang_analyzer_dump(a); // expected-warning {{conj_$}}
+ // FIXME: should be {{1 S32b}}.
+ clang_analyzer_dump(b); // expected-warning {{conj_$}}
+ // FIXME: should be {{uninitialized value}}.
+ } else if (Ret == 1) {
+ clang_analyzer_dump(a); // expected-warning {{conj_$}}
+ clang_analyzer_dump(b); // expected-warning {{conj_$}}
+ // FIXME: should be {{uninitialized value}}.
+ } else if (Ret >= 2) {
+ clang_analyzer_dump(a); // expected-warning {{conj_$}}
+ clang_analyzer_dump(b); // expected-warning {{conj_$}}
+ clang_analyzer_eval(Ret == 2); // expected-warning {{FALSE}} expected-warning {{TRUE}}
+ // FIXME: should be only TRUE.
+ } else {
+ clang_analyzer_dump(a); // expected-warning {{1 S32b}}
+ clang_analyzer_dump(b); // expected-warning {{uninitialized value}}
+ }
+
+ fclose(F);
+}
+
+void test_getdelim(char *P, size_t Sz) {
+ FILE *F = tmpfile();
+ if (!F)
+ return;
+
+ char *P1 = P;
+ size_t Sz1 = Sz;
+ ssize_t Ret = getdelim(&P, &Sz, '\t', F);
+ if (Ret < 0) {
+ clang_analyzer_eval(P == P1); // expected-warning {{FALSE}} \
+ // expected-warning {{TRUE}}
+ clang_analyzer_eval(Sz == Sz1); // expected-warning {{FALSE}} \
+ // expected-warning {{TRUE}}
+ } else {
+ clang_analyzer_eval(P == P1); // expected-warning {{FALSE}} \
+ // expected-warning {{TRUE}}
+ clang_analyzer_eval(Sz == Sz1); // expected-warning {{FALSE}} \
+ // expected-warning {{TRUE}}
+ }
+
+ fclose(F);
+}
+
+void test_fgetpos() {
+ FILE *F = tmpfile();
+ if (!F)
+ return;
+
+ fpos_t Pos = 1;
+ int Ret = fgetpos(F, &Pos);
+ if (Ret == 0) {
+ clang_analyzer_dump(Pos); // expected-warning {{conj_$}}
+ } else {
+ clang_analyzer_dump(Pos); // expected-warning {{1 S32b}}
+ }
+
+ fclose(F);
+}
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