2c82588dac
dfsan does not use sanitizer allocator as others. In practice, we let it use glibc's allocator since tcmalloc needs more work to be working with dfsan well. With glibc, we observe large memory leakage. This could relate to two things: 1) glibc allocator has limitation: for example, tcmalloc can reduce memory footprint 2x easily 2) glibc may call unmmap directly as an internal system call by using system call number. so DFSan has no way to release shadow spaces for those unmmap. Using sanitizer allocator addresses the above issues 1) its memory management is close to tcmalloc 2) we can register callback when sanitizer allocator calls unmmap, so dfsan can release shadow spaces correctly. Our experiment with internal server-based application proved that with the change, in a-few-day run, memory usage leakage is close to what tcmalloc does w/o dfsan. This change mainly follows MSan's code. 1) define allocator callbacks at dfsan_allocator.h|cpp 2) mark allocator APIs to be discard 3) intercept allocator APIs 4) make dfsan_set_label consistent with MSan's SetShadow when setting 0 labels, define dfsan_release_meta_memory when unmap is called 5) add flags about whether zeroing memory after malloc/free. dfsan works at byte-level, so bit-level oparations can cause reading undefined shadow. See D96842. zeroing memory after malloc helps this. About zeroing after free, reading after free is definitely UB, but if user code does so, it is hard to debug an overtainting caused by this w/o running MSan. So we add the flag to help debugging. This change will be split to small changes for review. Before that, a question is "this code shares a lot of with MSan, for example, dfsan_allocator.* and dfsan_new_delete.*. Does it make sense to unify the code at sanitizer_common? will that introduce some maintenance issue?" Reviewed By: morehouse Differential Revision: https://reviews.llvm.org/D101204
125 lines
4.0 KiB
C++
125 lines
4.0 KiB
C++
//===-- dfsan_new_delete.cpp ----------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file is a part of DataflowSanitizer.
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//
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// Interceptors for operators new and delete.
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//===----------------------------------------------------------------------===//
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#include <stddef.h>
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#include "dfsan.h"
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#include "interception/interception.h"
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#include "sanitizer_common/sanitizer_allocator.h"
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#include "sanitizer_common/sanitizer_allocator_report.h"
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using namespace __dfsan;
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// Fake std::nothrow_t and std::align_val_t to avoid including <new>.
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namespace std {
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struct nothrow_t {};
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enum class align_val_t : size_t {};
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} // namespace std
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// TODO(alekseys): throw std::bad_alloc instead of dying on OOM.
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#define OPERATOR_NEW_BODY(nothrow) \
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void *res = dfsan_malloc(size); \
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if (!nothrow && UNLIKELY(!res)) { \
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BufferedStackTrace stack; \
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ReportOutOfMemory(size, &stack); \
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} \
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return res
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#define OPERATOR_NEW_BODY_ALIGN(nothrow) \
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void *res = dfsan_memalign((uptr)align, size); \
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if (!nothrow && UNLIKELY(!res)) { \
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BufferedStackTrace stack; \
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ReportOutOfMemory(size, &stack); \
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} \
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return res;
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INTERCEPTOR_ATTRIBUTE
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void *operator new(size_t size) { OPERATOR_NEW_BODY(false /*nothrow*/); }
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INTERCEPTOR_ATTRIBUTE
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void *operator new[](size_t size) { OPERATOR_NEW_BODY(false /*nothrow*/); }
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INTERCEPTOR_ATTRIBUTE
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void *operator new(size_t size, std::nothrow_t const &) {
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OPERATOR_NEW_BODY(true /*nothrow*/);
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}
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INTERCEPTOR_ATTRIBUTE
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void *operator new[](size_t size, std::nothrow_t const &) {
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OPERATOR_NEW_BODY(true /*nothrow*/);
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}
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INTERCEPTOR_ATTRIBUTE
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void *operator new(size_t size, std::align_val_t align) {
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OPERATOR_NEW_BODY_ALIGN(false /*nothrow*/);
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}
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INTERCEPTOR_ATTRIBUTE
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void *operator new[](size_t size, std::align_val_t align) {
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OPERATOR_NEW_BODY_ALIGN(false /*nothrow*/);
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}
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INTERCEPTOR_ATTRIBUTE
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void *operator new(size_t size, std::align_val_t align,
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std::nothrow_t const &) {
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OPERATOR_NEW_BODY_ALIGN(true /*nothrow*/);
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}
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INTERCEPTOR_ATTRIBUTE
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void *operator new[](size_t size, std::align_val_t align,
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std::nothrow_t const &) {
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OPERATOR_NEW_BODY_ALIGN(true /*nothrow*/);
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}
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#define OPERATOR_DELETE_BODY \
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if (ptr) \
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dfsan_deallocate(ptr)
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INTERCEPTOR_ATTRIBUTE
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void operator delete(void *ptr)NOEXCEPT { OPERATOR_DELETE_BODY; }
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INTERCEPTOR_ATTRIBUTE
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void operator delete[](void *ptr) NOEXCEPT { OPERATOR_DELETE_BODY; }
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INTERCEPTOR_ATTRIBUTE
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void operator delete(void *ptr, std::nothrow_t const &) {
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OPERATOR_DELETE_BODY;
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}
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INTERCEPTOR_ATTRIBUTE
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void operator delete[](void *ptr, std::nothrow_t const &) {
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OPERATOR_DELETE_BODY;
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}
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INTERCEPTOR_ATTRIBUTE
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void operator delete(void *ptr, size_t size)NOEXCEPT { OPERATOR_DELETE_BODY; }
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INTERCEPTOR_ATTRIBUTE
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void operator delete[](void *ptr, size_t size) NOEXCEPT {
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OPERATOR_DELETE_BODY;
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}
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INTERCEPTOR_ATTRIBUTE
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void operator delete(void *ptr, std::align_val_t align)NOEXCEPT {
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OPERATOR_DELETE_BODY;
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}
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INTERCEPTOR_ATTRIBUTE
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void operator delete[](void *ptr, std::align_val_t align) NOEXCEPT {
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OPERATOR_DELETE_BODY;
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}
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INTERCEPTOR_ATTRIBUTE
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void operator delete(void *ptr, std::align_val_t align,
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std::nothrow_t const &) {
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OPERATOR_DELETE_BODY;
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}
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INTERCEPTOR_ATTRIBUTE
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void operator delete[](void *ptr, std::align_val_t align,
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std::nothrow_t const &) {
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OPERATOR_DELETE_BODY;
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}
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INTERCEPTOR_ATTRIBUTE
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void operator delete(void *ptr, size_t size, std::align_val_t align)NOEXCEPT {
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OPERATOR_DELETE_BODY;
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}
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INTERCEPTOR_ATTRIBUTE
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void operator delete[](void *ptr, size_t size,
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std::align_val_t align) NOEXCEPT {
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OPERATOR_DELETE_BODY;
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}
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