GWP-ASan: Increase allocations on canary/dev

In r624120 I reduced the number of allocations used by GWP-ASan from
MaxAllocations/TotalPages 32/128 to 6/20. These are good parameters for
widespread use to limit the amount of memory/perf regression on stable;
however, it makes it much less likely GWP-ASan will catch newly
introduced bugs on canary/dev. Add a multiplier by which to increase the
GWP-ASan parameters on canary/dev to ensure we maintain good coverage of
new code.

Bug: 896019
Change-Id: I1ce59c25878ef0c066e04a0dedeba1f3aa97ec0d
Reviewed-on: https://chromium-review.googlesource.com/c/1429240
Commit-Queue: Vlad Tsyrklevich <vtsyrklevich@chromium.org>
Reviewed-by: Vitaly Buka <vitalybuka@chromium.org>
Reviewed-by: Ken Rockot <rockot@google.com>
Auto-Submit: Vlad Tsyrklevich <vtsyrklevich@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626105}

chrome/app/chrome_main_delegate.cc

@@ -530,7 +530,10 @@ bool ChromeMainDelegate::ShouldCreateFeatureList() {
 
 void ChromeMainDelegate::PostFieldTrialInitialization() {
 #if defined(OS_WIN)
-  gwp_asan::EnableForMalloc();
+  version_info::Channel channel = chrome::GetChannel();
+  bool is_canary_dev = (channel == version_info::Channel::CANARY ||
+                        channel == version_info::Channel::DEV);
+  gwp_asan::EnableForMalloc(is_canary_dev);
 #endif
 }
 

components/gwp_asan/client/gwp_asan.cc

@@ -4,12 +4,15 @@
 
 #include "components/gwp_asan/client/gwp_asan.h"
 
+#include <algorithm>
+#include <limits>
+
 #include "base/debug/crash_logging.h"
 #include "base/feature_list.h"
 #include "base/logging.h"
 #include "base/macros.h"
 #include "base/metrics/field_trial_params.h"
-#include "base/numerics/safe_conversions.h"
+#include "base/numerics/safe_math.h"
 #include "base/rand_util.h"
 #include "base/strings/stringprintf.h"
 #include "components/gwp_asan/client/guarded_page_allocator.h"
@@ -34,13 +37,20 @@ const base::FeatureParam<int> kAllocationSamplingParam{
 const base::FeatureParam<double> kProcessSamplingParam{
     &kGwpAsan, "ProcessSamplingProbability", 1.0};
 
-bool EnableForMalloc() {
+// The multiplier to increase MaxAllocations/TotalPages on canary/dev builds.
+const base::FeatureParam<int> kCanaryDevMultiplierParam{
+    &kGwpAsan, "CanaryDevMultiplier", 5};
+
+bool EnableForMalloc(bool is_canary_dev) {
   if (!base::FeatureList::IsEnabled(kGwpAsan))
     return false;
 
+  static_assert(AllocatorState::kGpaMaxPages <= std::numeric_limits<int>::max(),
+                "kGpaMaxPages out of range");
+  constexpr int kMaxPages = static_cast<int>(AllocatorState::kGpaMaxPages);
+
   int total_pages = kTotalPagesParam.Get();
-  if (total_pages < 1 ||
-      total_pages > base::checked_cast<int>(AllocatorState::kGpaMaxPages)) {
+  if (total_pages < 1 || total_pages > kMaxPages) {
     DLOG(ERROR) << "GWP-ASan TotalPages is out-of-range: " << total_pages;
     return false;
   }
@@ -67,6 +77,31 @@ bool EnableForMalloc() {
     return false;
   }
 
+  int multiplier = 1;
+  if (is_canary_dev)
+    multiplier = kCanaryDevMultiplierParam.Get();
+
+  if (multiplier < 1 || multiplier > kMaxPages) {
+    DLOG(ERROR) << "GWP-ASan CanaryDevMultiplier is out-of-range: "
+                << multiplier;
+    return false;
+  }
+
+  base::CheckedNumeric<int> total_pages_mult = total_pages;
+  total_pages_mult *= multiplier;
+  base::CheckedNumeric<int> max_allocations_mult = max_allocations;
+  max_allocations_mult *= multiplier;
+
+  if (!total_pages_mult.IsValid() || !max_allocations_mult.IsValid()) {
+    DLOG(ERROR) << "GWP-ASan multiplier caused out-of-range multiply: "
+                << multiplier;
+    return false;
+  }
+
+  total_pages = std::min<int>(total_pages_mult.ValueOrDie(), kMaxPages);
+  max_allocations =
+      std::min<int>(max_allocations_mult.ValueOrDie(), total_pages);
+
   if (base::RandDouble() >= process_sampling_probability)
     return false;
 
@@ -77,8 +112,8 @@ bool EnableForMalloc() {
 }  // namespace
 }  // namespace internal
 
-void EnableForMalloc() {
-  static bool init_once = internal::EnableForMalloc();
+void EnableForMalloc(bool is_canary_dev) {
+  static bool init_once = internal::EnableForMalloc(is_canary_dev);
   ignore_result(init_once);
 }
 

components/gwp_asan/client/gwp_asan.h

@@ -10,8 +10,9 @@
 namespace gwp_asan {
 
 // Enable GWP-ASan for the current process. This should only be called once per
-// process. This can not be disabled once it has been enabled.
-GWP_ASAN_EXPORT void EnableForMalloc();
+// process. This can not be disabled once it has been enabled. The caller should
+// indicate whether this build is a canary or dev build.
+GWP_ASAN_EXPORT void EnableForMalloc(bool is_canary_dev);
 
 }  // namespace gwp_asan