[compiler-rt] Make mmap-munmap interceptor fail earlier (PR #171295)

[Thurston Dang via llvm-commits]

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@@ -159,43 +192,90 @@ DECLARE_REAL_AND_INTERCEPTOR(void, free, void*)
 template <class Mmap>
 static void* mmap_interceptor(Mmap real_mmap, void* addr, SIZE_T length,
                               int prot, int flags, int fd, OFF64_T offset) {
+  if (length == 0)
+    return real_mmap(addr, length, prot, flags, fd, offset);
+
+#  if SANITIZER_POSIX
+  uptr start = reinterpret_cast<uptr>(addr);
+  uptr end_excl;
+  if (UNLIKELY(__builtin_add_overflow(start, (uptr)length, &end_excl))) {
+    errno = errno_EINVAL;
+    return (void*)-1;
+  }
+
+  if (flags & map_fixed) {
+    if (__asan::IntersectsShadowOrGap(start, end_excl)) {
+      errno = errno_EINVAL;
+      return (void*)-1;
+    }
+    if (!AddrIsInMem(start) || !AddrIsInMem(end_excl - 1)) {
+      errno = errno_ENOMEM;
+      return (void*)-1;
+    }
+  } else {
+    if (addr && __asan::IntersectsShadowOrGap(start, start + 1))
+      addr = nullptr;
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thurstond wrote:

cuda_test.cpp fails (https://github.com/llvm/llvm-project/actions/runs/21395345315/job/61605235935?pr=171295) when protect_shadow_gap=0



https://github.com/llvm/llvm-project/pull/171295