devnexen created this revision.
devnexen added a reviewer: dergachev.a.
Herald added a subscriber: cfe-commits.
In addition of checking mmap call, checking as well mprotect to detect possible
writable-executable promotions.
Repository:
rC Clang
https://reviews.llvm.org/D44250
Files:
lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
test/Analysis/mmap-writeexec.c
Index: test/Analysis/mmap-writeexec.c
===================================================================
--- test/Analysis/mmap-writeexec.c
+++ test/Analysis/mmap-writeexec.c
@@ -16,6 +16,7 @@
typedef __typeof(sizeof(int)) size_t;
void *mmap(void *, size_t, int, int, int, long);
+int mprotect(void *, size_t, int);
void f1()
{
@@ -34,3 +35,10 @@
int prot = PROT_WRITE | PROT_EXEC;
(void)callm(NULL, 1024, prot, MAP_PRIVATE | MAP_ANON, -1, 0); //
expected-warning{{Both PROT_WRITE and PROT_EXEC flags are set. This can lead to
exploitable memory regions, which could be overwritten with malicious code}}
}
+
+void f3()
+{
+ void *p = mmap(NULL, 1024, PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0); //
no-warning
+ int m = mprotect(p, 1024, PROT_WRITE | PROT_EXEC); // expected-warning{{Both
PROT_WRITE and PROT_EXEC flags are set. This can lead to exploitable memory
regions, which could be overwritten with malicious code}}
+ (void)m;
+}
Index: lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
+++ lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
@@ -28,12 +28,13 @@
namespace {
class MmapWriteExecChecker : public Checker<check::PreCall> {
CallDescription MmapFn;
+ CallDescription MprotectFn;
static int ProtWrite;
static int ProtExec;
static int ProtRead;
mutable std::unique_ptr<BugType> BT;
public:
- MmapWriteExecChecker() : MmapFn("mmap", 6) {}
+ MmapWriteExecChecker() : MmapFn("mmap", 6), MprotectFn("mprotect", 3) {}
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
int ProtExecOv;
int ProtReadOv;
@@ -46,8 +47,8 @@
void MmapWriteExecChecker::checkPreCall(const CallEvent &Call,
CheckerContext &C) const {
- if (Call.isCalled(MmapFn)) {
- SVal ProtVal = Call.getArgSVal(2);
+ if (Call.isCalled(MmapFn) || Call.isCalled(MprotectFn)) {
+ SVal ProtVal = Call.getArgSVal(2);
Optional<nonloc::ConcreteInt> ProtLoc =
ProtVal.getAs<nonloc::ConcreteInt>();
int64_t Prot = ProtLoc->getValue().getSExtValue();
if (ProtExecOv != ProtExec)
Index: test/Analysis/mmap-writeexec.c
===================================================================
--- test/Analysis/mmap-writeexec.c
+++ test/Analysis/mmap-writeexec.c
@@ -16,6 +16,7 @@
typedef __typeof(sizeof(int)) size_t;
void *mmap(void *, size_t, int, int, int, long);
+int mprotect(void *, size_t, int);
void f1()
{
@@ -34,3 +35,10 @@
int prot = PROT_WRITE | PROT_EXEC;
(void)callm(NULL, 1024, prot, MAP_PRIVATE | MAP_ANON, -1, 0); // expected-warning{{Both PROT_WRITE and PROT_EXEC flags are set. This can lead to exploitable memory regions, which could be overwritten with malicious code}}
}
+
+void f3()
+{
+ void *p = mmap(NULL, 1024, PROT_WRITE, MAP_PRIVATE | MAP_ANON, -1, 0); // no-warning
+ int m = mprotect(p, 1024, PROT_WRITE | PROT_EXEC); // expected-warning{{Both PROT_WRITE and PROT_EXEC flags are set. This can lead to exploitable memory regions, which could be overwritten with malicious code}}
+ (void)m;
+}
Index: lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
===================================================================
--- lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
+++ lib/StaticAnalyzer/Checkers/MmapWriteExecChecker.cpp
@@ -28,12 +28,13 @@
namespace {
class MmapWriteExecChecker : public Checker<check::PreCall> {
CallDescription MmapFn;
+ CallDescription MprotectFn;
static int ProtWrite;
static int ProtExec;
static int ProtRead;
mutable std::unique_ptr<BugType> BT;
public:
- MmapWriteExecChecker() : MmapFn("mmap", 6) {}
+ MmapWriteExecChecker() : MmapFn("mmap", 6), MprotectFn("mprotect", 3) {}
void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
int ProtExecOv;
int ProtReadOv;
@@ -46,8 +47,8 @@
void MmapWriteExecChecker::checkPreCall(const CallEvent &Call,
CheckerContext &C) const {
- if (Call.isCalled(MmapFn)) {
- SVal ProtVal = Call.getArgSVal(2);
+ if (Call.isCalled(MmapFn) || Call.isCalled(MprotectFn)) {
+ SVal ProtVal = Call.getArgSVal(2);
Optional<nonloc::ConcreteInt> ProtLoc = ProtVal.getAs<nonloc::ConcreteInt>();
int64_t Prot = ProtLoc->getValue().getSExtValue();
if (ProtExecOv != ProtExec)
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