[compiler-rt] [compiler-rt][rtsan] mremap for Linux interception. (PR #124234)

[David CARLIER via llvm-commits]

https://github.com/devnexen updated https://github.com/llvm/llvm-project/pull/124234

>From 1fd415fcf5207bdb2154bb65c781c1913e19195c Mon Sep 17 00:00:00 2001
From: David Carlier <devnexen at gmail.com>
Date: Fri, 24 Jan 2025 06:28:56 +0000
Subject: [PATCH 1/2] [compiler-rt][rtsan] mremap for Linux interception.

---
 .../lib/rtsan/rtsan_interceptors_posix.cpp    | 28 +++++++++++++++++++
 .../tests/rtsan_test_interceptors_posix.cpp   | 10 +++++++
 2 files changed, 38 insertions(+)

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);

>From e133beeca49d2b5632924e215d7bdb311add1c81 Mon Sep 17 00:00:00 2001
From: David Carlier <devnexen at gmail.com>
Date: Mon, 27 Jan 2025 12:36:47 +0000
Subject: [PATCH 2/2] changes from feedback

---
 compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp b/compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp
index 79fb46bf603976..9932fe07d85227 100644
--- a/compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp
+++ b/compiler-rt/lib/rtsan/rtsan_interceptors_posix.cpp
@@ -852,25 +852,25 @@ INTERCEPTOR(void *, mmap64, void *addr, size_t length, int prot, int flags,
 #endif // SANITIZER_INTERCEPT_MMAP64
 
 #if SANITIZER_LINUX
-// Note that even if rtsan is ported to netbsd, it has a different signature
-// still
+// Note that even if rtsan is ported to netbsd, it has a slighty different
+// and non-variadic signature
 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 *);
+    void *naddr = va_arg(args, void *);
     va_end(args);
+
+    return REAL(mremap)(oaddr, olength, nlength, flags, naddr);
   }
 
-  return REAL(mremap)(oaddr, olength, nlength, flags, naddr);
+  return REAL(mremap)(oaddr, olength, nlength, flags);
 }
 #define RTSAN_MAYBE_INTERCEPT_MREMAP INTERCEPT_FUNCTION(mremap)
 #else