fix: Fix over-read and NULL deref in __hipstdpar_realloc

projects/rocthrust/test/hipstdpar/CMakeLists.txt

@@ -104,6 +104,7 @@ set(ROCPRIM_LOCATION ${ROCPRIM_INCLUDE_DIR})
 # Add tests
 add_hipstdpar_test("algorithms" "compile" OFF)
 add_hipstdpar_test("interpose" "compile" ON)
+add_hipstdpar_test("realloc" "run" ON)
 
 # Restore global state
 set(CMAKE_CXX_STANDARD ${ROCTHRUST_CMAKE_CXX_STANDARD})

projects/rocthrust/test/hipstdpar/test_realloc.cpp

@@ -0,0 +1,159 @@
+// MIT License
+//
+// Copyright (c) 2026 Advanced Micro Devices, Inc. All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all
+// copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+// Regression test for __hipstdpar_realloc, which is what std::realloc resolves
+// to when translation units are compiled with --hipstdpar-interpose-alloc.
+//
+// The interposer used to copy n (the requested new size) bytes out of the old
+// block unconditionally. Growing an allocation therefore over-read past the end
+// of the old block, and realloc(nullptr, n) fed a NULL pointer straight to
+// memcpy. This test exercises the fixed contract:
+//   * realloc(nullptr, n) behaves like malloc(n),
+//   * realloc(p, 0)       frees p and returns nullptr,
+//   * growing preserves every byte of the old block (no over-read),
+//   * shrinking preserves the retained prefix.
+//
+// Interposed allocations are backed by hipMallocManaged, so the storage is
+// host-accessible and the payload can be validated directly on the host.
+
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+
+namespace
+{
+// Deterministic, size-dependent fill so a stale/short copy is detectable.
+std::uint8_t pattern(std::size_t i)
+{
+  return static_cast<std::uint8_t>((i * 31u + 7u) & 0xffu);
+}
+
+void fill(std::uint8_t* p, std::size_t n)
+{
+  for (std::size_t i = 0; i < n; ++i)
+  {
+    p[i] = pattern(i);
+  }
+}
+
+bool verify(const std::uint8_t* p, std::size_t n)
+{
+  for (std::size_t i = 0; i < n; ++i)
+  {
+    if (p[i] != pattern(i))
+    {
+      return false;
+    }
+  }
+  return true;
+}
+} // namespace
+
+int main()
+{
+  try
+  {
+    // realloc(nullptr, n) must behave like malloc(n).
+    {
+      auto p = static_cast<std::uint8_t*>(std::realloc(nullptr, 64));
+      if (!p)
+      {
+        return EXIT_FAILURE;
+      }
+      fill(p, 64);
+      if (!verify(p, 64))
+      {
+        return EXIT_FAILURE;
+      }
+      std::free(p);
+    }
+
+    // realloc(p, 0) must free p and return nullptr.
+    {
+      auto p = std::malloc(64);
+      if (!p)
+      {
+        return EXIT_FAILURE;
+      }
+      if (std::realloc(p, 0) != nullptr)
+      {
+        return EXIT_FAILURE;
+      }
+    }
+
+    // Growing must preserve the whole old block without over-reading past it.
+    {
+      constexpr std::size_t old_size = 32;
+      constexpr std::size_t new_size = 8192;
+
+      auto p = static_cast<std::uint8_t*>(std::malloc(old_size));
+      if (!p)
+      {
+        return EXIT_FAILURE;
+      }
+      fill(p, old_size);
+
+      auto q = static_cast<std::uint8_t*>(std::realloc(p, new_size));
+      if (!q)
+      {
+        return EXIT_FAILURE;
+      }
+      if (!verify(q, old_size))
+      {
+        std::free(q);
+        return EXIT_FAILURE;
+      }
+      std::free(q);
+    }
+
+    // Shrinking must preserve the retained prefix.
+    {
+      constexpr std::size_t old_size = 8192;
+      constexpr std::size_t new_size = 32;
+
+      auto p = static_cast<std::uint8_t*>(std::malloc(old_size));
+      if (!p)
+      {
+        return EXIT_FAILURE;
+      }
+      fill(p, old_size);
+
+      auto q = static_cast<std::uint8_t*>(std::realloc(p, new_size));
+      if (!q)
+      {
+        return EXIT_FAILURE;
+      }
+      if (!verify(q, new_size))
+      {
+        std::free(q);
+        return EXIT_FAILURE;
+      }
+      std::free(q);
+    }
+  }
+  catch (...)
+  {
+    return EXIT_FAILURE;
+  }
+
+  return EXIT_SUCCESS;
+}

projects/rocthrust/thrust/system/hip/hipstdpar/impl/interpose_allocations_v0.hpp

@@ -42,13 +42,19 @@
 #  if defined(__HIPSTDPAR_INTERPOSE_ALLOC__)
 #    include <hip/hip_runtime.h>
 
+#    include <algorithm>
 #    include <cstddef>
 #    include <cstdint>
 #    include <cstring>
 #    include <memory_resource>
 #    include <new>
 #    include <stdexcept>
 
+#    if __has_include(<malloc.h>)
+#      include <malloc.h>
+#      define __HIPSTDPAR_HAS_MALLOC_USABLE_SIZE__
+#    endif
+
 namespace hipstd
 {
 struct Header
@@ -132,7 +138,22 @@ extern "C" __attribute__((weak)) void __hipstdpar_hidden_free(void*);
 
 extern "C" inline __attribute__((used)) void* __hipstdpar_realloc(void* p, std::size_t n)
 {
-  auto q = std::memcpy(__hipstdpar_malloc(n), p, n);
+  if (!p)
+  {
+    return __hipstdpar_malloc(n);
+  }
+
+  if (n == 0)
+  {
+    __hipstdpar_free(p);
+    return nullptr;
+  }
+
+  auto q = __hipstdpar_malloc(n);
+  if (!q)
+  {
+    return nullptr;
+  }
 
   auto h = static_cast<hipstd::Header*>(p) - 1;
 
@@ -141,10 +162,18 @@ extern "C" inline __attribute__((used)) void* __hipstdpar_realloc(void* p, std::
 
   if (!tmp.isManaged)
   {
+    std::size_t old = n;
+#    if defined(__HIPSTDPAR_HAS_MALLOC_USABLE_SIZE__)
+    old = malloc_usable_size(p);
+#    endif
+    std::memcpy(q, p, std::min(old, n));
     __hipstdpar_hidden_free(p);
   }
   else
   {
+    const auto old = reinterpret_cast<std::uintptr_t>(h->alloc_ptr) + h->size
+                     - reinterpret_cast<std::uintptr_t>(p);
+    std::memcpy(q, p, std::min<std::size_t>(old, n));
     hipstd::heap.deallocate(h->alloc_ptr, h->size, h->align);
   }
 

projects/rocthrust/thrust/system/hip/hipstdpar/impl/interpose_allocations_v1.hpp

@@ -33,6 +33,7 @@
     #include <sys/unistd.h>
 #endif
 
+#include <algorithm>
 #include <climits>
 #include <cstddef>
 #include <cstdint>
@@ -42,6 +43,11 @@
 #include <stdexcept>
 #include <utility>
 
+#if __has_include(<malloc.h>)
+    #include <malloc.h>
+    #define __HIPSTDPAR_HAS_MALLOC_USABLE_SIZE__
+#endif
+
 extern "C" {
     __attribute__((weak)) void __hipstdpar_hidden_free(void*);
     __attribute__((weak)) void* __hipstdpar_hidden_memalign(::std::size_t,
@@ -165,7 +171,21 @@ extern "C" {
     inline __attribute__((used)) void* __hipstdpar_realloc(void* p,
                                                            std::size_t n)
     {
-        auto q = std::memcpy(__hipstdpar_malloc(n), p, n);
+        if (!p) return __hipstdpar_malloc(n);
+
+        if (n == 0) {
+            __hipstdpar_free(p);
+            return nullptr;
+        }
+
+        auto q = __hipstdpar_malloc(n);
+        if (!q) return nullptr;
+
+        std::size_t old = n;
+        #if defined(__HIPSTDPAR_HAS_MALLOC_USABLE_SIZE__)
+            old = malloc_usable_size(p);
+        #endif
+        std::memcpy(q, p, std::min(old, n));
         __hipstdpar_free(p);
 
         return q;