Index: lib/hwasan/CMakeLists.txt =================================================================== --- lib/hwasan/CMakeLists.txt +++ lib/hwasan/CMakeLists.txt @@ -24,6 +24,7 @@ hwasan_flags.h hwasan_flags.inc hwasan_interface_internal.h + hwasan_malloc_bisect.h hwasan_mapping.h hwasan_poisoning.h hwasan_report.h Index: lib/hwasan/hwasan_allocator.cc =================================================================== --- lib/hwasan/hwasan_allocator.cc +++ lib/hwasan/hwasan_allocator.cc @@ -17,6 +17,7 @@ #include "hwasan.h" #include "hwasan_allocator.h" #include "hwasan_mapping.h" +#include "hwasan_malloc_bisect.h" #include "hwasan_thread.h" #include "hwasan_report.h" @@ -181,7 +182,7 @@ // retag to 0. if ((flags()->tag_in_malloc || flags()->tag_in_free) && atomic_load_relaxed(&hwasan_allocator_tagging_enabled)) { - tag_t tag = flags()->tag_in_malloc + tag_t tag = flags()->tag_in_malloc && malloc_bisect(stack, orig_size) ? (t ? t->GenerateRandomTag() : kFallbackAllocTag) : 0; user_ptr = (void *)TagMemoryAligned((uptr)user_ptr, size, tag); @@ -247,7 +248,7 @@ Min(TaggedSize(orig_size), (uptr)flags()->max_free_fill_size); internal_memset(aligned_ptr, flags()->free_fill_byte, fill_size); } - if (flags()->tag_in_free && + if (flags()->tag_in_free && malloc_bisect(stack, 0) && atomic_load_relaxed(&hwasan_allocator_tagging_enabled)) TagMemoryAligned(reinterpret_cast(aligned_ptr), TaggedSize(orig_size), t ? t->GenerateRandomTag() : kFallbackFreeTag); Index: lib/hwasan/hwasan_flags.inc =================================================================== --- lib/hwasan/hwasan_flags.inc +++ lib/hwasan/hwasan_flags.inc @@ -85,3 +85,16 @@ "The number of stack frames remembered per thread. " "Affects the quality of stack-related reports, but not the ability " "to find bugs.") + +// Malloc / free bisection. Only tag malloc and free calls when a hash of +// allocation size and stack trace is between malloc_bisect_left and +// malloc_bisect_right (both inclusive). [0, 0] range is special and disables +// bisection (i.e. everything is tagged). Once the range is narrowed down +// enough, use malloc_bisect_dump to see interesting allocations. +HWASAN_FLAG(uptr, malloc_bisect_left, 0, + "Left bound of malloc bisection, inclusive.") +HWASAN_FLAG(uptr, malloc_bisect_right, 0, + "Right bound of malloc bisection, inclusive.") +HWASAN_FLAG(bool, malloc_bisect_dump, false, + "Print all allocations within [malloc_bisect_left, " + "malloc_bisect_right] range ") Index: lib/hwasan/hwasan_malloc_bisect.h =================================================================== --- lib/hwasan/hwasan_malloc_bisect.h +++ lib/hwasan/hwasan_malloc_bisect.h @@ -0,0 +1,50 @@ +//===-- hwasan_malloc_bisect.h ----------------------------------*- C++ -*-===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file is a part of HWAddressSanitizer. +// +//===----------------------------------------------------------------------===// + +#include "sanitizer_common/sanitizer_hash.h" +#include "hwasan.h" + +namespace __hwasan { + +static u32 malloc_hash(StackTrace *stack, uptr orig_size) { + uptr len = Min(stack->size, (unsigned)7); + MurMur2HashBuilder H(len); + H.add(orig_size); + // Start with frame #1 to skip __sanitizer_malloc frame, which is + // (a) almost always the same (well, could be operator new or new[]) + // (b) can change hashes when compiler-rt is rebuilt, invalidating previous + // bisection results. + // Because of ASLR, use only offset inside the page. + for (uptr i = 1; i < len; ++i) H.add(((u32)stack->trace[i]) & 0xFFF); + return H.get(); +} + +static INLINE bool malloc_bisect(StackTrace *stack, uptr orig_size) { + uptr left = flags()->malloc_bisect_left; + uptr right = flags()->malloc_bisect_right; + if (LIKELY(left == 0 && right == 0)) + return true; + if (!stack) + return true; + // Allow malloc_bisect_right > (u32)(-1) to avoid spelling the latter in + // decimal. + uptr h = (uptr)malloc_hash(stack, orig_size); + if (h < left || h > right) + return false; + if (flags()->malloc_bisect_dump) { + Printf("[alloc] %u %zu\n", h, orig_size); + stack->Print(); + } + return true; +} + +} // namespace __hwasan Index: lib/sanitizer_common/CMakeLists.txt =================================================================== --- lib/sanitizer_common/CMakeLists.txt +++ lib/sanitizer_common/CMakeLists.txt @@ -142,6 +142,7 @@ sanitizer_freebsd.h sanitizer_fuchsia.h sanitizer_getauxval.h + sanitizer_hash.h sanitizer_interceptors_ioctl_netbsd.inc sanitizer_interface_internal.h sanitizer_internal_defs.h Index: lib/sanitizer_common/sanitizer_hash.h =================================================================== --- lib/sanitizer_common/sanitizer_hash.h +++ lib/sanitizer_common/sanitizer_hash.h @@ -0,0 +1,43 @@ +//===-- sanitizer_common.h --------------------------------------*- C++ -*-===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This file implements a simple hash function. +//===----------------------------------------------------------------------===// + +#ifndef SANITIZER_HASH_H +#define SANITIZER_HASH_H + +#include "sanitizer_internal_defs.h" + +namespace __sanitizer { +class MurMur2HashBuilder { + static const u32 m = 0x5bd1e995; + static const u32 seed = 0x9747b28c; + static const u32 r = 24; + u32 h; + + public: + explicit MurMur2HashBuilder(u32 init = 0) { h = seed ^ init; } + void add(u32 k) { + k *= m; + k ^= k >> r; + k *= m; + h *= m; + h ^= k; + } + u32 get() { + u32 x = h; + x ^= x >> 13; + x *= m; + x ^= x >> 15; + return x; + } +}; +} //namespace __sanitizer + +#endif // SANITIZER_HASH_H Index: lib/sanitizer_common/sanitizer_stackdepot.cc =================================================================== --- lib/sanitizer_common/sanitizer_stackdepot.cc +++ lib/sanitizer_common/sanitizer_stackdepot.cc @@ -13,6 +13,7 @@ #include "sanitizer_stackdepot.h" #include "sanitizer_common.h" +#include "sanitizer_hash.h" #include "sanitizer_stackdepotbase.h" namespace __sanitizer { @@ -49,23 +50,9 @@ return sizeof(StackDepotNode) + (args.size - 1) * sizeof(uptr); } static u32 hash(const args_type &args) { - // murmur2 - const u32 m = 0x5bd1e995; - const u32 seed = 0x9747b28c; - const u32 r = 24; - u32 h = seed ^ (args.size * sizeof(uptr)); - for (uptr i = 0; i < args.size; i++) { - u32 k = args.trace[i]; - k *= m; - k ^= k >> r; - k *= m; - h *= m; - h ^= k; - } - h ^= h >> 13; - h *= m; - h ^= h >> 15; - return h; + MurMur2HashBuilder H(args.size * sizeof(uptr)); + for (uptr i = 0; i < args.size; i++) H.add(args.trace[i]); + return H.get(); } static bool is_valid(const args_type &args) { return args.size > 0 && args.trace; Index: test/hwasan/TestCases/malloc_bisect.c =================================================================== --- test/hwasan/TestCases/malloc_bisect.c +++ test/hwasan/TestCases/malloc_bisect.c @@ -0,0 +1,26 @@ +// RUN: %clang_hwasan -O0 %s -o %t +// RUN: %env_hwasan_opts=malloc_bisect_left=0,malloc_bisect_right=0 not %run %t 2>&1 | \ +// RUN: FileCheck %s --check-prefix=CRASH +// RUN: %env_hwasan_opts=malloc_bisect_left=1000,malloc_bisect_right=999 %run %t 2>&1 +// RUN: %env_hwasan_opts=malloc_bisect_left=0,malloc_bisect_right=4294967295 not %run %t 2>&1 | \ +// RUN: FileCheck %s --check-prefix=CRASH +// RUN: %env_hwasan_opts=malloc_bisect_left=0,malloc_bisect_right=4294967295,malloc_bisect_dump=1 not %run %t 2>&1 | \ +// RUN: FileCheck %s --check-prefixes=CRASH,DUMP + +#include +#include +#include + +int main() { + __hwasan_enable_allocator_tagging(); + // DUMP: [alloc] {{.*}} 10{{$}} + // DUMP: in main{{.*}}malloc_bisect.c + char * volatile p = (char*)malloc(10); + // CRASH: HWAddressSanitizer: tag-mismatch on address + // CRASH: in main{{.*}}malloc_bisect.c + char volatile x = p[16]; + free(p); + __hwasan_disable_allocator_tagging(); + + return 0; +}