[compiler-rt][rtsan] mremap for Linux interception.

[devnexen]

No description provided.

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: David CARLIER (devnexen)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/124234.diff

2 Files Affected:

• (modified) compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp (+28)
• (modified) compiler-rt/lib/rtsan/tests/rtsan_test_interceptors_posix.cpp (+10)

diff --git a/compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp b/compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp
index 1b499f2194f212..79fb46bf603976 100644
--- a/compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp
+++ b/compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp
@@ -47,6 +47,7 @@ void OSSpinLockLock(volatile OSSpinLock *__lock);
 #include <stdarg.h>
 #include <stdio.h>
 #if SANITIZER_LINUX
+#include <linux/mman.h>
 #include <sys/inotify.h>
 #endif
 #include <sys/select.h>
@@ -850,6 +851,32 @@ INTERCEPTOR(void *, mmap64, void *addr, size_t length, int prot, int flags,
 #define RTSAN_MAYBE_INTERCEPT_MMAP64
 #endif // SANITIZER_INTERCEPT_MMAP64
 
+#if SANITIZER_LINUX
+// Note that even if rtsan is ported to netbsd, it has a different signature
+// still
+INTERCEPTOR(void *, mremap, void *oaddr, size_t olength, size_t nlength,
+            int flags, ...) {
+  __rtsan_notify_intercepted_call("mremap");
+
+  void *naddr = nullptr;
+
+  // the last optional argument is only used in this case
+  // as the new page region will be assigned to. Is ignored otherwise.
+  if (flags & MREMAP_FIXED) {
+    va_list args;
+
+    va_start(args, flags);
+    naddr = va_arg(args, void *);
+    va_end(args);
+  }
+
+  return REAL(mremap)(oaddr, olength, nlength, flags, naddr);
+}
+#define RTSAN_MAYBE_INTERCEPT_MREMAP INTERCEPT_FUNCTION(mremap)
+#else
+#define RTSAN_MAYBE_INTERCEPT_MREMAP
+#endif
+
 INTERCEPTOR(int, munmap, void *addr, size_t length) {
   __rtsan_notify_intercepted_call("munmap");
   return REAL(munmap)(addr, length);
@@ -1321,6 +1348,7 @@ void __rtsan::InitializeInterceptors() {
   INTERCEPT_FUNCTION(posix_memalign);
   INTERCEPT_FUNCTION(mmap);
   RTSAN_MAYBE_INTERCEPT_MMAP64;
+  RTSAN_MAYBE_INTERCEPT_MREMAP;
   INTERCEPT_FUNCTION(munmap);
   RTSAN_MAYBE_INTERCEPT_MADVISE;
   RTSAN_MAYBE_INTERCEPT_POSIX_MADVISE;
diff --git a/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors_posix.cpp b/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors_posix.cpp
index a4f2b92b7c4945..7bff31e561a85d 100644
--- a/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors_posix.cpp
+++ b/compiler-rt/lib/rtsan/tests/rtsan_test_interceptors_posix.cpp
@@ -197,6 +197,16 @@ TEST(TestRtsanInterceptors, MmapDiesWhenRealtime) {
   ExpectNonRealtimeSurvival(Func);
 }
 
+#if SANITIZER_LINUX
+TEST(TestRtsanInterceptors, MremapDiesWhenRealtime) {
+  void *addr = mmap(nullptr, 8, PROT_READ | PROT_WRITE,
+                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
+  auto Func = [addr]() { void *_ = mremap(addr, 8, 16, 0); };
+  ExpectRealtimeDeath(Func, "mremap");
+  ExpectNonRealtimeSurvival(Func);
+}
+#endif
+
 TEST(TestRtsanInterceptors, MunmapDiesWhenRealtime) {
   void *ptr = mmap(nullptr, 8, PROT_READ | PROT_WRITE,
                    MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

[cjappl]

I'm unclear on what this comment means, could you rephrase it?

[cjappl]

For this will you follow the pattern set forth in our open/openat interceptor? that is, call REAL in two places so we don't have to pass in nullptr on 873?