[Sanitizers] ASan: detect new/delete calls with mismatched alignment.

ASan allocator stores the requested alignment for new and new[] calls
and on delete and delete[] verifies that alignments do match.

The representable alignments are: default alignment, 8, 16, 32, 64, 128,
256 and 512 bytes. Alignments > 512 are stored as 512, hence two
different alignments > 512 will pass the check (possibly masking the bug),
but limited memory requirements deemed to be a resonable tradeoff for
relaxed conditions.

The feature is controlled by new_delete_type_mismatch flag, the same one
protecting new/delete matching size check.

Differential revision: https://reviews.llvm.org/D38574

Issue: https://github.com/google/sanitizers/issues/799
llvm-svn: 316595

1 files changed, 23 insertions, 5 deletions

diff --git a/compiler-rt/lib/asan/asan_errors.cc b/compiler-rt/lib/asan/asan_errors.cc
index dee666d54ff..6413b987b24 100644
--- a/compiler-rt/lib/asan/asan_errors.cc
+++ b/compiler-rt/lib/asan/asan_errors.cc
@@ -63,7 +63,7 @@ void ErrorDoubleFree::Print() {
   ReportErrorSummary(scariness.GetDescription(), &stack);
 }
 
-void ErrorNewDeleteSizeMismatch::Print() {
+void ErrorNewDeleteTypeMismatch::Print() {
   Decorator d;
   Printf("%s", d.Warning());
   char tname[128];
@@ -73,10 +73,28 @@ void ErrorNewDeleteSizeMismatch::Print() {
       scariness.GetDescription(), addr_description.addr, tid,
       ThreadNameWithParenthesis(tid, tname, sizeof(tname)));
   Printf("%s  object passed to delete has wrong type:\n", d.Default());
-  Printf(
-      "  size of the allocated type:   %zd bytes;\n"
-      "  size of the deallocated type: %zd bytes.\n",
-      addr_description.chunk_access.chunk_size, delete_size);
+  if (delete_size != 0) {
+    Printf(
+        "  size of the allocated type:   %zd bytes;\n"
+        "  size of the deallocated type: %zd bytes.\n",
+        addr_description.chunk_access.chunk_size, delete_size);
+  }
+  const uptr user_alignment =
+      addr_description.chunk_access.user_requested_alignment;
+  if (delete_alignment != user_alignment) {
+    char user_alignment_str[32];
+    char delete_alignment_str[32];
+    internal_snprintf(user_alignment_str, sizeof(user_alignment_str),
+                      "%zd bytes", user_alignment);
+    internal_snprintf(delete_alignment_str, sizeof(delete_alignment_str),
+                      "%zd bytes", delete_alignment);
+    static const char *kDefaultAlignment = "default-aligned";
+    Printf(
+        "  alignment of the allocated type:   %s;\n"
+        "  alignment of the deallocated type: %s.\n",
+        user_alignment > 0 ? user_alignment_str : kDefaultAlignment,
+        delete_alignment > 0 ? delete_alignment_str : kDefaultAlignment);
+  }
   CHECK_GT(free_stack->size, 0);
   scariness.Print();
   GET_STACK_TRACE_FATAL(free_stack->trace[0], free_stack->top_frame_bp);