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[hwasan] Add malloc_fill_byte and free_fill_byte flags. 

Reviewers: vitalybuka, kcc

Subscribers: kubamracek, llvm-commits

Differential Revision: https://reviews.llvm.org/D50753

llvm-svn: 339932
This commit is contained in:
Evgeniy Stepanov 2018-08-16 20:13:09 +00:00
parent bb1aede865
commit fa9f78553a
3 changed files with 44 additions and 1 deletions
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10
compiler-rt/lib/hwasan/hwasan_allocator.cc
View File

@ -156,8 +156,12 @@ static void *HwasanAllocate(StackTrace *stack, uptr size, uptr alignment,
meta->state = CHUNK_ALLOCATED;
meta->requested_size = size;
meta->alloc_context_id = StackDepotPut(*stack);
if (zeroise)
if (zeroise) {
internal_memset(allocated, 0, size);
} else if (flags()->max_malloc_fill_size > 0) {
uptr fill_size = Min(size, (uptr)flags()->max_malloc_fill_size);
internal_memset(allocated, flags()->malloc_fill_byte, fill_size);
}
void *user_ptr = allocated;
if (flags()->tag_in_malloc &&
@ -182,6 +186,10 @@ void HwasanDeallocate(StackTrace *stack, void *user_ptr) {
// This memory will not be reused by anyone else, so we are free to keep it
// poisoned.
HwasanThread *t = GetCurrentThread();
if (flags()->max_free_fill_size > 0) {
uptr fill_size = Min(size, (uptr)flags()->max_free_fill_size);
internal_memset(p, flags()->free_fill_byte, fill_size);
}
if (flags()->tag_in_free &&
atomic_load_relaxed(&hwasan_allocator_tagging_enabled))
TagMemoryAligned((uptr)p, size,

13
compiler-rt/lib/hwasan/hwasan_flags.inc
View File

@ -31,3 +31,16 @@ HWASAN_FLAG(bool, disable_allocator_tagging, false, "")
// If false, use simple increment of a thread local counter to generate new
// tags.
HWASAN_FLAG(bool, random_tags, true, "")
HWASAN_FLAG(
int, max_malloc_fill_size, 0x1000, // By default, fill only the first 4K.
"HWASan allocator flag. max_malloc_fill_size is the maximal amount of "
"bytes that will be filled with malloc_fill_byte on malloc.")
HWASAN_FLAG(
int, max_free_fill_size, 0,
"HWASan allocator flag. max_free_fill_size is the maximal amount of "
"bytes that will be filled with free_fill_byte during free.")
HWASAN_FLAG(int, malloc_fill_byte, 0xbe,
"Value used to fill the newly allocated memory.")
HWASAN_FLAG(int, free_fill_byte, 0x55,
"Value used to fill deallocated memory.")

22
compiler-rt/test/hwasan/TestCases/malloc_fill.cc Normal file
View File

@ -0,0 +1,22 @@
// Check that we fill malloc-ed memory correctly.
// RUN: %clangxx_hwasan %s -o %t
// RUN: %run %t | FileCheck %s
// RUN: %env_hwasan_opts=max_malloc_fill_size=10:malloc_fill_byte=8 %run %t | FileCheck %s --check-prefix=CHECK-10-8
// RUN: %env_hwasan_opts=max_malloc_fill_size=20:malloc_fill_byte=171 %run %t | FileCheck %s --check-prefix=CHECK-20-ab
#include <stdio.h>
int main(int argc, char **argv) {
// With asan allocator this makes sure we get memory from mmap.
static const int kSize = 1 << 25;
unsigned char *x = new unsigned char[kSize];
printf("-");
for (int i = 0; i <= 32; i++) {
printf("%02x", x[i]);
}
printf("-\n");
delete [] x;
}
// CHECK: -bebebebebebebebebebebebebebebebebebebebebebebebebebebebebebebebebe-
// CHECK-10-8: -080808080808080808080000000000000000000000000000000000000000000000-
// CHECK-20-ab: -abababababababababababababababababababab00000000000000000000000000-