[scudo] 32-bit quarantine sizes adjustments and bug fixes

Summary:
The local and global quarantine sizes were not offering a distinction for
32-bit and 64-bit platforms. This is addressed with lower values for 32-bit.

When writing additional tests for the quarantine, it was discovered that when
calling some of the allocator interface function prior to any allocation
operation having occured, the test would crash due to the allocator not being
initialized. This was addressed by making sure the allocator is initialized
for those scenarios.

Relevant tests were added in interface.cpp and quarantine.cpp.

Last change being the removal of the extraneous link dependencies for the
tests thanks to rL293220, anf the addition of the gc-sections linker flag.

Reviewers: kcc, alekseyshl

Reviewed By: alekseyshl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29341

llvm-svn: 294037

18 files changed, 143 insertions, 125 deletions

diff --git a/compiler-rt/lib/scudo/scudo_allocator.cpp b/compiler-rt/lib/scudo/scudo_allocator.cpp
index a6d6aafe31f..dab6abedcb3 100644
--- a/compiler-rt/lib/scudo/scudo_allocator.cpp
+++ b/compiler-rt/lib/scudo/scudo_allocator.cpp
@@ -354,6 +354,8 @@ struct Allocator {
 
   // Helper function that checks for a valid Scudo chunk.
   bool isValidPointer(const void *UserPtr) {
+    if (UNLIKELY(!ThreadInited))
+      initThread();
     uptr ChunkBeg = reinterpret_cast<uptr>(UserPtr);
     if (!IsAligned(ChunkBeg, MinAlignment)) {
       return false;
@@ -580,6 +582,14 @@ struct Allocator {
     AllocatorQuarantine.Drain(&ThreadQuarantineCache,
                               QuarantineCallback(&Cache));
   }
+
+  uptr getStats(AllocatorStat StatType) {
+    if (UNLIKELY(!ThreadInited))
+      initThread();
+    uptr stats[AllocatorStatCount];
+    BackendAllocator.GetStats(stats);
+    return stats[StatType];
+  }
 };
 
 static Allocator Instance(LINKER_INITIALIZED);
@@ -664,15 +674,11 @@ using namespace __scudo;
 // MallocExtension helper functions
 
 uptr __sanitizer_get_current_allocated_bytes() {
-  uptr stats[AllocatorStatCount];
-  getAllocator().GetStats(stats);
-  return stats[AllocatorStatAllocated];
+  return Instance.getStats(AllocatorStatAllocated);
 }
 
 uptr __sanitizer_get_heap_size() {
-  uptr stats[AllocatorStatCount];
-  getAllocator().GetStats(stats);
-  return stats[AllocatorStatMapped];
+  return Instance.getStats(AllocatorStatMapped);
 }
 
 uptr __sanitizer_get_free_bytes() {
diff --git a/compiler-rt/lib/scudo/scudo_flags.cpp b/compiler-rt/lib/scudo/scudo_flags.cpp
index b9c83810730..64da1d9d8ec 100644
--- a/compiler-rt/lib/scudo/scudo_flags.cpp
+++ b/compiler-rt/lib/scudo/scudo_flags.cpp
@@ -68,7 +68,7 @@ void initFlags() {
   // Sanity checks and default settings for the Quarantine parameters.
 
   if (f->QuarantineSizeMb < 0) {
-    const int DefaultQuarantineSizeMb = 64;
+    const int DefaultQuarantineSizeMb = FIRST_32_SECOND_64(16, 64);
     f->QuarantineSizeMb = DefaultQuarantineSizeMb;
   }
   // We enforce an upper limit for the quarantine size of 4Gb.
@@ -76,7 +76,8 @@ void initFlags() {
     dieWithMessage("ERROR: the quarantine size is too large\n");
   }
   if (f->ThreadLocalQuarantineSizeKb < 0) {
-    const int DefaultThreadLocalQuarantineSizeKb = 1024;
+    const int DefaultThreadLocalQuarantineSizeKb =
+        FIRST_32_SECOND_64(256, 1024);
     f->ThreadLocalQuarantineSizeKb = DefaultThreadLocalQuarantineSizeKb;
   }
   // And an upper limit of 128Mb for the thread quarantine cache.
@@ -84,6 +85,10 @@ void initFlags() {
     dieWithMessage("ERROR: the per thread quarantine cache size is too "
                    "large\n");
   }
+  if (f->ThreadLocalQuarantineSizeKb == 0 && f->QuarantineSizeMb > 0) {
+    dieWithMessage("ERROR: ThreadLocalQuarantineSizeKb can be set to 0 only "
+                   "when QuarantineSizeMb is set to 0\n");
+  }
 }
 
 Flags *getFlags() {
diff --git a/compiler-rt/lib/scudo/scudo_flags.inc b/compiler-rt/lib/scudo/scudo_flags.inc
index c7a2acf146c..45f9ea846e1 100644
--- a/compiler-rt/lib/scudo/scudo_flags.inc
+++ b/compiler-rt/lib/scudo/scudo_flags.inc
@@ -15,12 +15,14 @@
 # error "Define SCUDO_FLAG prior to including this file!"
 #endif
 
-SCUDO_FLAG(int, QuarantineSizeMb, 64,
+// Default value is set in scudo_flags.cpp based on architecture.
+SCUDO_FLAG(int, QuarantineSizeMb, -1,
            "Size (in Mb) of quarantine used to delay the actual deallocation "
            "of chunks. Lower value may reduce memory usage but decrease the "
            "effectiveness of the mitigation.")
 
-SCUDO_FLAG(int, ThreadLocalQuarantineSizeKb, 1024,
+// Default value is set in scudo_flags.cpp based on architecture.
+SCUDO_FLAG(int, ThreadLocalQuarantineSizeKb, -1,
           "Size (in Kb) of per-thread cache used to offload the global "
           "quarantine. Lower value may reduce memory usage but might increase "
           "the contention on the global quarantine.")
diff --git a/compiler-rt/test/scudo/alignment.cpp b/compiler-rt/test/scudo/alignment.cpp
index a6eca87a822..125ad8cbe76 100644
--- a/compiler-rt/test/scudo/alignment.cpp
+++ b/compiler-rt/test/scudo/alignment.cpp
@@ -14,8 +14,7 @@ int main(int argc, char **argv)
   assert(argc == 2);
   if (!strcmp(argv[1], "pointers")) {
     void *p = malloc(1U << 16);
-    if (!p)
-      return 1;
+    assert(p);
     free(reinterpret_cast<void *>(reinterpret_cast<uintptr_t>(p) | 1));
   }
   return 0;
diff --git a/compiler-rt/test/scudo/double-free.cpp b/compiler-rt/test/scudo/double-free.cpp
index 75919f0c459..ddc520505ed 100644
--- a/compiler-rt/test/scudo/double-free.cpp
+++ b/compiler-rt/test/scudo/double-free.cpp
@@ -16,30 +16,26 @@ int main(int argc, char **argv)
   assert(argc == 2);
   if (!strcmp(argv[1], "malloc")) {
     void *p = malloc(sizeof(int));
-    if (!p)
-      return 1;
+    assert(p);
     free(p);
     free(p);
   }
   if (!strcmp(argv[1], "new")) {
     int *p = new int;
-    if (!p)
-      return 1;
+    assert(p);
     delete p;
     delete p;
   }
   if (!strcmp(argv[1], "newarray")) {
     int *p = new int[8];
-    if (!p)
-      return 1;
+    assert(p);
     delete[] p;
     delete[] p;
   }
   if (!strcmp(argv[1], "memalign")) {
     void *p = nullptr;
     posix_memalign(&p, 0x100, sizeof(int));
-    if (!p)
-      return 1;
+    assert(p);
     free(p);
     free(p);
   }
diff --git a/compiler-rt/test/scudo/interface.cpp b/compiler-rt/test/scudo/interface.cpp
index 55de174322b..c5a88778008 100644
--- a/compiler-rt/test/scudo/interface.cpp
+++ b/compiler-rt/test/scudo/interface.cpp
@@ -1,9 +1,13 @@
 // RUN: %clang_scudo %s -lstdc++ -o %t
-// RUN: %run %t 2>&1
+// RUN: %run %t ownership          2>&1
+// RUN: %run %t ownership-and-size 2>&1
+// RUN: %run %t heap-size          2>&1
 
 // Tests that the sanitizer interface functions behave appropriately.
 
 #include <stdlib.h>
+#include <assert.h>
+#include <string.h>
 
 #include <vector>
 
@@ -11,18 +15,33 @@
 
 int main(int argc, char **argv)
 {
-  void *p;
-  std::vector<ssize_t> sizes{1, 8, 16, 32, 1024, 32768,
-    1 << 16, 1 << 17, 1 << 20, 1 << 24};
-  for (size_t size : sizes) {
-    p = malloc(size);
-    if (!p)
-      return 1;
-    if (!__sanitizer_get_ownership(p))
-      return 1;
-    if (__sanitizer_get_allocated_size(p) < size)
-      return 1;
-    free(p);
+  assert(argc == 2);
+
+  if (!strcmp(argv[1], "ownership")) {
+    // Ensures that __sanitizer_get_ownership can be called before any other
+    // allocator function, and that it behaves properly on a pointer not owned
+    // by us.
+    assert(!__sanitizer_get_ownership(argv));
+  }
+  if (!strcmp(argv[1], "ownership-and-size")) {
+    // Tests that __sanitizer_get_ownership and __sanitizer_get_allocated_size
+    // behave properly on chunks allocated by the Primary and Secondary.
+    void *p;
+    std::vector<ssize_t> sizes{1, 8, 16, 32, 1024, 32768,
+      1 << 16, 1 << 17, 1 << 20, 1 << 24};
+    for (size_t size : sizes) {
+      p = malloc(size);
+      assert(p);
+      assert(__sanitizer_get_ownership(p));
+      assert(__sanitizer_get_allocated_size(p) >= size);
+      free(p);
+    }
   }
+  if (!strcmp(argv[1], "heap-size")) {
+    // Ensures that __sanitizer_get_heap_size can be called before any other
+    // allocator function. At this point, this heap size should be 0.
+    assert(__sanitizer_get_heap_size() == 0);
+  }
+
   return 0;
 }
diff --git a/compiler-rt/test/scudo/lit.cfg b/compiler-rt/test/scudo/lit.cfg
index b0476303cc1..0fa44087ead 100644
--- a/compiler-rt/test/scudo/lit.cfg
+++ b/compiler-rt/test/scudo/lit.cfg
@@ -19,12 +19,12 @@ config.suffixes = ['.c', '.cc', '.cpp']
 # C flags.
 c_flags = ([config.target_cflags] +
            ["-std=c++11",
-           "-lrt",
-           "-ldl",
            "-pthread",
            "-fPIE",
            "-pie",
-           "-O0"])
+           "-O0",
+           "-UNDEBUG",
+           "-Wl,--gc-sections"])
 
 def build_invocation(compile_flags):                                            
   return " " + " ".join([config.clang] + compile_flags) + " "                   
diff --git a/compiler-rt/test/scudo/malloc.cpp b/compiler-rt/test/scudo/malloc.cpp
index fbe57a8cbab..50e52590f56 100644
--- a/compiler-rt/test/scudo/malloc.cpp
+++ b/compiler-rt/test/scudo/malloc.cpp
@@ -5,6 +5,7 @@
 // intended. Tests various sizes serviced by the primary and secondary
 // allocators.
 
+#include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -18,8 +19,7 @@ int main(int argc, char **argv)
   std::vector<int> offsets{1, 0, -1, -7, -8, -15, -16, -31, -32};
 
   p = malloc(0);
-  if (!p)
-    return 1;
+  assert(p);
   free(p);
   for (ssize_t size : sizes) {
     for (int offset: offsets) {
@@ -27,8 +27,7 @@ int main(int argc, char **argv)
       if (actual_size <= 0)
         continue;
       p = malloc(actual_size);
-      if (!p)
-        return 1;
+      assert(p);
       memset(p, 0xff, actual_size);
       free(p);
     }
diff --git a/compiler-rt/test/scudo/memalign.cpp b/compiler-rt/test/scudo/memalign.cpp
index b407ec57434..c263da75e61 100644
--- a/compiler-rt/test/scudo/memalign.cpp
+++ b/compiler-rt/test/scudo/memalign.cpp
@@ -29,12 +29,10 @@ int main(int argc, char **argv)
 
   if (!strcmp(argv[1], "valid")) {
     posix_memalign(&p, alignment, size);
-    if (!p)
-      return 1;
+    assert(p);
     free(p);
     p = aligned_alloc(alignment, size);
-    if (!p)
-      return 1;
+    assert(p);
     free(p);
     // Tests various combinations of alignment and sizes
     for (int i = (sizeof(void *) == 4) ? 3 : 4; i < 19; i++) {
@@ -43,8 +41,7 @@ int main(int argc, char **argv)
         size = 0x800 * j;
         for (int k = 0; k < 3; k++) {
           p = memalign(alignment, size - (2 * sizeof(void *) * k));
-          if (!p)
-            return 1;
+          assert(p);
           free(p);
         }
       }
@@ -54,8 +51,7 @@ int main(int argc, char **argv)
     for (int i = 19; i <= 24; i++) {
       for (int k = 0; k < 3; k++) {
         p = memalign(alignment, 0x1000 - (2 * sizeof(void *) * k));
-        if (!p)
-          return 1;
+        assert(p);
         free(p);
       }
     }
diff --git a/compiler-rt/test/scudo/mismatch.cpp b/compiler-rt/test/scudo/mismatch.cpp
index 54cdafc86ee..15dce83ce18 100644
--- a/compiler-rt/test/scudo/mismatch.cpp
+++ b/compiler-rt/test/scudo/mismatch.cpp
@@ -10,29 +10,26 @@
 // caught when the related option is set.
 
 #include <assert.h>
+#include <malloc.h>
 #include <stdlib.h>
 #include <string.h>
-#include <malloc.h>
 
 int main(int argc, char **argv)
 {
   assert(argc == 2);
   if (!strcmp(argv[1], "mallocdel")) {
     int *p = (int *)malloc(16);
-    if (!p)
-      return 1;
+    assert(p);
     delete p;
   }
   if (!strcmp(argv[1], "newfree")) {
     int *p = new int;
-    if (!p)
-      return 1;
+    assert(p);
     free((void *)p);
   }
   if (!strcmp(argv[1], "memaligndel")) {
     int *p = (int *)memalign(16, 16);
-    if (!p)
-      return 1;
+    assert(p);
     delete p;
   }
   return 0;
diff --git a/compiler-rt/test/scudo/options.cpp b/compiler-rt/test/scudo/options.cpp
index bccf7c8fbd2..f4afe7d79bf 100644
--- a/compiler-rt/test/scudo/options.cpp
+++ b/compiler-rt/test/scudo/options.cpp
@@ -6,8 +6,9 @@
 // Tests that the options can be passed using getScudoDefaultOptions, and that
 // the environment ones take precedence over them.
 
-#include <stdlib.h>
+#include <assert.h>
 #include <malloc.h>
+#include <stdlib.h>
 
 extern "C" const char* __scudo_default_options() {
   return "DeallocationTypeMismatch=0";  // Defaults to true in scudo_flags.inc.
@@ -16,8 +17,7 @@ extern "C" const char* __scudo_default_options() {
 int main(int argc, char **argv)
 {
   int *p = (int *)malloc(16);
-  if (!p)
-    return 1;
+  assert(p);
   delete p;
   return 0;
 }
diff --git a/compiler-rt/test/scudo/overflow.cpp b/compiler-rt/test/scudo/overflow.cpp
index c93a544ea0a..d1282457852 100644
--- a/compiler-rt/test/scudo/overflow.cpp
+++ b/compiler-rt/test/scudo/overflow.cpp
@@ -10,20 +10,20 @@
 
 int main(int argc, char **argv)
 {
-  assert(argc == 2);
   ssize_t offset = sizeof(void *) == 8 ? 8 : 0;
+
+  assert(argc == 2);
+
   if (!strcmp(argv[1], "malloc")) {
     // Simulate a header corruption of an allocated chunk (1-bit)
     void *p = malloc(1U << 4);
-    if (!p)
-      return 1;
+    assert(p);
     ((char *)p)[-(offset + 1)] ^= 1;
     free(p);
   }
   if (!strcmp(argv[1], "quarantine")) {
     void *p = malloc(1U << 4);
-    if (!p)
-      return 1;
+    assert(p);
     free(p);
     // Simulate a header corruption of a quarantined chunk
     ((char *)p)[-(offset + 2)] ^= 1;
diff --git a/compiler-rt/test/scudo/preinit.cpp b/compiler-rt/test/scudo/preinit.cpp
index 34f61c9ddfb..b8c01a401dd 100644
--- a/compiler-rt/test/scudo/preinit.cpp
+++ b/compiler-rt/test/scudo/preinit.cpp
@@ -4,6 +4,7 @@
 // Verifies that calling malloc in a preinit_array function succeeds, and that
 // the resulting pointer can be freed at program termination.
 
+#include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -23,8 +24,7 @@ void __fini(void) {
 int main(int argc, char **argv)
 {
   void *p = malloc(1);
-  if (!p)
-    return 1;
+  assert(p);
   free(p);
 
   return 0;
@@ -34,4 +34,3 @@ __attribute__((section(".preinit_array"), used))
   void (*__local_preinit)(void) = __init;
 __attribute__((section(".fini_array"), used))
   void (*__local_fini)(void) = __fini;
-
diff --git a/compiler-rt/test/scudo/quarantine.cpp b/compiler-rt/test/scudo/quarantine.cpp
index 4ce0197acde..39ce1bd91d3 100644
--- a/compiler-rt/test/scudo/quarantine.cpp
+++ b/compiler-rt/test/scudo/quarantine.cpp
@@ -1,43 +1,57 @@
 // RUN: %clang_scudo %s -o %t
-// RUN: SCUDO_OPTIONS=QuarantineSizeMb=1 %run %t 2>&1
+// RUN: SCUDO_OPTIONS="QuarantineSizeMb=0:ThreadLocalQuarantineSizeKb=0" %run %t zeroquarantine 2>&1
+// RUN: SCUDO_OPTIONS=QuarantineSizeMb=1                                 %run %t smallquarantine 2>&1
 
 // Tests that the quarantine prevents a chunk from being reused right away.
 // Also tests that a chunk will eventually become available again for
 // allocation when the recycling criteria has been met.
 
+#include <assert.h>
 #include <malloc.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include <sanitizer/allocator_interface.h>
+
 int main(int argc, char **argv)
 {
   void *p, *old_p;
-  size_t size = 1U << 16;
-
-  // The delayed freelist will prevent a chunk from being available right away
-  p = malloc(size);
-  if (!p)
-    return 1;
-  old_p = p;
-  free(p);
-  p = malloc(size);
-  if (!p)
-    return 1;
-  if (old_p == p)
-    return 1;
-  free(p);
-
-  // Eventually the chunk should become available again
-  bool found = false;
-  for (int i = 0; i < 0x100 && found == false; i++) {
+  size_t allocated_bytes, size = 1U << 16;
+
+  assert(argc == 2);
+
+  if (!strcmp(argv[1], "zeroquarantine")) {
+    // Verifies that a chunk is deallocated right away when the local and
+    // global quarantine sizes are 0.
+    allocated_bytes = __sanitizer_get_current_allocated_bytes();
     p = malloc(size);
-    if (!p)
-      return 1;
-    found = (p == old_p);
+    assert(p);
+    assert(__sanitizer_get_current_allocated_bytes() > allocated_bytes);
     free(p);
+    assert(__sanitizer_get_current_allocated_bytes() == allocated_bytes);
+  }
+  if (!strcmp(argv[1], "smallquarantine")) {
+    // The delayed freelist will prevent a chunk from being available right
+    // away.
+    p = malloc(size);
+    assert(p);
+    old_p = p;
+    free(p);
+    p = malloc(size);
+    assert(p);
+    assert(old_p != p);
+    free(p);
+
+    // Eventually the chunk should become available again.
+    bool found = false;
+    for (int i = 0; i < 0x100 && found == false; i++) {
+      p = malloc(size);
+      assert(p);
+      found = (p == old_p);
+      free(p);
+    }
+    assert(found == true);
   }
-  if (found == false)
-    return 1;
 
   return 0;
 }
diff --git a/compiler-rt/test/scudo/realloc.cpp b/compiler-rt/test/scudo/realloc.cpp
index d34e356fb52..da377205f10 100644
--- a/compiler-rt/test/scudo/realloc.cpp
+++ b/compiler-rt/test/scudo/realloc.cpp
@@ -23,48 +23,41 @@ int main(int argc, char **argv)
   std::vector<size_t> sizes{1, 16, 1024, 32768, 1 << 16, 1 << 17, 1 << 20};
 
   assert(argc == 2);
+
   for (size_t size : sizes) {
     if (!strcmp(argv[1], "pointers")) {
       old_p = p = realloc(nullptr, size);
-      if (!p)
-        return 1;
+      assert(p);
       size = malloc_usable_size(p);
       // Our realloc implementation will return the same pointer if the size
       // requested is lower than or equal to the usable size of the associated
       // chunk.
       p = realloc(p, size - 1);
-      if (p != old_p)
-        return 1;
+      assert(p == old_p);
       p = realloc(p, size);
-      if (p != old_p)
-        return 1;
+      assert(p == old_p);
       // And a new one if the size is greater.
       p = realloc(p, size + 1);
-      if (p == old_p)
-        return 1;
+      assert(p != old_p);
       // A size of 0 will free the chunk and return nullptr.
       p = realloc(p, 0);
-      if (p)
-        return 1;
+      assert(!p);
       old_p = nullptr;
     }
     if (!strcmp(argv[1], "contents")) {
       p = realloc(nullptr, size);
-      if (!p)
-        return 1;
+      assert(p);
       for (int i = 0; i < size; i++)
         reinterpret_cast<char *>(p)[i] = 'A';
       p = realloc(p, size + 1);
       // The contents of the reallocated chunk must match the original one.
       for (int i = 0; i < size; i++)
-        if (reinterpret_cast<char *>(p)[i] != 'A')
-          return 1;
+        assert(reinterpret_cast<char *>(p)[i] == 'A');
     }
     if (!strcmp(argv[1], "memalign")) {
       // A chunk coming from memalign cannot be reallocated.
       p = memalign(16, size);
-      if (!p)
-        return 1;
+      assert(p);
       p = realloc(p, size);
       free(p);
     }
diff --git a/compiler-rt/test/scudo/secondary.cpp b/compiler-rt/test/scudo/secondary.cpp
index 7a634a81eb0..dc14f8ca846 100644
--- a/compiler-rt/test/scudo/secondary.cpp
+++ b/compiler-rt/test/scudo/secondary.cpp
@@ -5,12 +5,12 @@
 // Test that we hit a guard page when writing past the end of a chunk
 // allocated by the Secondary allocator, or writing too far in front of it.
 
+#include <assert.h>
 #include <malloc.h>
+#include <signal.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
-#include <signal.h>
-#include <assert.h>
 
 void handler(int signo, siginfo_t *info, void *uctx) {
   if (info->si_code == SEGV_ACCERR) {
@@ -33,8 +33,7 @@ int main(int argc, char **argv)
   a.sa_flags = SA_SIGINFO;
 
   char *p = (char *)malloc(size);
-  if (!p)
-    return 1;
+  assert(p);
   memset(p, 'A', size); // This should not trigger anything.
   // Set up the SIGSEGV handler now, as the rest should trigger an AV.
   sigaction(SIGSEGV, &a, nullptr);
diff --git a/compiler-rt/test/scudo/sized-delete.cpp b/compiler-rt/test/scudo/sized-delete.cpp
index 5b1bf5fd4cb..e467f556520 100644
--- a/compiler-rt/test/scudo/sized-delete.cpp
+++ b/compiler-rt/test/scudo/sized-delete.cpp
@@ -10,11 +10,12 @@
 // option is passed and the sizes do not match between allocation and
 // deallocation functions.
 
-#include <new>
 #include <assert.h>
 #include <stdlib.h>
 #include <string.h>
 
+#include <new>
+
 int main(int argc, char **argv)
 {
   assert(argc == 2);
diff --git a/compiler-rt/test/scudo/sizes.cpp b/compiler-rt/test/scudo/sizes.cpp
index 7190cb64f33..981b859a875 100644
--- a/compiler-rt/test/scudo/sizes.cpp
+++ b/compiler-rt/test/scudo/sizes.cpp
@@ -23,35 +23,28 @@ int main(int argc, char **argv)
     // Currently the maximum size the allocator can allocate is 1ULL<<40 bytes.
     size_t size = std::numeric_limits<size_t>::max();
     void *p = malloc(size);
-    if (p)
-      return 1;
+    assert(!p);
     size = (1ULL << 40) - 16;
     p = malloc(size);
-    if (p)
-      return 1;
+    assert(!p);
   }
   if (!strcmp(argv[1], "calloc")) {
     // Trigger an overflow in calloc.
     size_t size = std::numeric_limits<size_t>::max();
     void *p = calloc((size / 0x1000) + 1, 0x1000);
-    if (p)
-      return 1;
+    assert(!p);
   }
   if (!strcmp(argv[1], "usable")) {
     // Playing with the actual usable size of a chunk.
     void *p = malloc(1007);
-    if (!p)
-      return 1;
+    assert(p);
     size_t size = malloc_usable_size(p);
-    if (size < 1007)
-      return 1;
+    assert(size >= 1007);
     memset(p, 'A', size);
     p = realloc(p, 2014);
-    if (!p)
-      return 1;
+    assert(p);
     size = malloc_usable_size(p);
-    if (size < 2014)
-      return 1;
+    assert(size >= 2014);
     memset(p, 'B', size);
     free(p);
   }