[PATCH] D39260: [asan] Don't print rows of shadow bytes outside shadow memory

[Reid Kleckner via Phabricator via llvm-commits]

rnk created this revision.
Herald added a subscriber: kubamracek.

They might not be mapped on some platforms such as Win64.  In
particular, this happens if the user address is null. There will not be
any shadow memory 5*16 bytes before the user address.


https://reviews.llvm.org/D39260

Files:
  compiler-rt/lib/asan/asan_errors.cc


Index: compiler-rt/lib/asan/asan_errors.cc
===================================================================
--- compiler-rt/lib/asan/asan_errors.cc
+++ compiler-rt/lib/asan/asan_errors.cc
@@ -422,9 +422,15 @@
   InternalScopedString str(4096 * 8);
   str.append("Shadow bytes around the buggy address:\n");
   for (int i = -5; i <= 5; i++) {
+    uptr row_addr = aligned_shadow + i * n_bytes_per_row;
+    // Skip rows that would be outside the shadow range. This can happen when
+    // the user address is near the bottom, top, or shadow gap of the address
+    // space.
+    if (!AddrIsInShadow(row_addr))
+      continue;
     const char *prefix = (i == 0) ? "=>" : "  ";
-    PrintShadowBytes(&str, prefix, (u8 *)(aligned_shadow + i * n_bytes_per_row),
-                     (u8 *)shadow_addr, n_bytes_per_row);
+    PrintShadowBytes(&str, prefix, (u8 *)row_addr, (u8 *)shadow_addr,
+                     n_bytes_per_row);
   }
   if (flags()->print_legend) PrintLegend(&str);
   Printf("%s", str.data());


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