[compiler-rt] c6f2142 - Reland "[DFSan] Handle fast16labels for all API functions."

[Matt Morehouse via llvm-commits]

Author: Matt Morehouse
Date: 2020-07-23T21:19:39Z
New Revision: c6f21424288971b976b987eacb094be5038aa328

URL: https://github.com/llvm/llvm-project/commit/c6f21424288971b976b987eacb094be5038aa328
DIFF: https://github.com/llvm/llvm-project/commit/c6f21424288971b976b987eacb094be5038aa328.diff

LOG: Reland "[DFSan] Handle fast16labels for all API functions."

Support fast16labels in `dfsan_has_label`, and print an error for all
other API functions.  For `dfsan_dump_labels` we return silently rather
than crashing since it is also called from the atexit handler where it
is undefined behavior to call exit() again.

Reviewed By: kcc

Differential Revision: https://reviews.llvm.org/D84215

Added: 
    

Modified: 
    compiler-rt/lib/dfsan/dfsan.cpp
    compiler-rt/test/dfsan/fast16labels.c

Removed: 
    


################################################################################
diff  --git a/compiler-rt/lib/dfsan/dfsan.cpp b/compiler-rt/lib/dfsan/dfsan.cpp
index 0e2fb9f5f334..105989c93ab1 100644
--- a/compiler-rt/lib/dfsan/dfsan.cpp
+++ b/compiler-rt/lib/dfsan/dfsan.cpp
@@ -158,6 +158,12 @@ static void dfsan_check_label(dfsan_label label) {
   }
 }
 
+static void ReportUnsupportedFast16(const char *func) {
+  Report("FATAL: DataFlowSanitizer: %s is unsupported in fast16labels mode\n",
+         func);
+  Die();
+}
+
 // Resolves the union of two unequal labels.  Nonequality is a precondition for
 // this function (the instrumentation pass inlines the equality test).
 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
@@ -253,8 +259,10 @@ dfsan_union(dfsan_label l1, dfsan_label l2) {
 
 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 dfsan_label dfsan_create_label(const char *desc, void *userdata) {
+  if (flags().fast16labels)
+    ReportUnsupportedFast16("dfsan_create_label");
   dfsan_label label =
-    atomic_fetch_add(&__dfsan_last_label, 1, memory_order_relaxed) + 1;
+      atomic_fetch_add(&__dfsan_last_label, 1, memory_order_relaxed) + 1;
   dfsan_check_label(label);
   __dfsan_label_info[label].l1 = __dfsan_label_info[label].l2 = 0;
   __dfsan_label_info[label].desc = desc;
@@ -311,11 +319,15 @@ dfsan_read_label(const void *addr, uptr size) {
 
 extern "C" SANITIZER_INTERFACE_ATTRIBUTE
 const struct dfsan_label_info *dfsan_get_label_info(dfsan_label label) {
+  if (flags().fast16labels)
+    ReportUnsupportedFast16("dfsan_get_label_info");
   return &__dfsan_label_info[label];
 }
 
 extern "C" SANITIZER_INTERFACE_ATTRIBUTE int
 dfsan_has_label(dfsan_label label, dfsan_label elem) {
+  if (flags().fast16labels)
+    return label & elem;
   if (label == elem)
     return true;
   const dfsan_label_info *info = dfsan_get_label_info(label);
@@ -328,6 +340,8 @@ dfsan_has_label(dfsan_label label, dfsan_label elem) {
 
 extern "C" SANITIZER_INTERFACE_ATTRIBUTE dfsan_label
 dfsan_has_label_with_desc(dfsan_label label, const char *desc) {
+  if (flags().fast16labels)
+    ReportUnsupportedFast16("dfsan_has_label_with_desc");
   const dfsan_label_info *info = dfsan_get_label_info(label);
   if (info->l1 != 0) {
     return dfsan_has_label_with_desc(info->l1, desc) ||
@@ -347,9 +361,11 @@ dfsan_get_label_count(void) {
 
 extern "C" SANITIZER_INTERFACE_ATTRIBUTE void
 dfsan_dump_labels(int fd) {
+  if (flags().fast16labels)
+    return;
+
   dfsan_label last_label =
       atomic_load(&__dfsan_last_label, memory_order_relaxed);
-
   for (uptr l = 1; l <= last_label; ++l) {
     char buf[64];
     internal_snprintf(buf, sizeof(buf), "%u %u %u ", l,

diff  --git a/compiler-rt/test/dfsan/fast16labels.c b/compiler-rt/test/dfsan/fast16labels.c
index a9b716039540..269d1e2efc0a 100644
--- a/compiler-rt/test/dfsan/fast16labels.c
+++ b/compiler-rt/test/dfsan/fast16labels.c
@@ -1,4 +1,11 @@
-// RUN: %clang_dfsan %s -o %t && DFSAN_OPTIONS=fast16labels=1 %run %t
+// RUN: %clang_dfsan %s -o %t
+// RUN: DFSAN_OPTIONS=fast16labels=1 %run %t
+// RUN: DFSAN_OPTIONS=fast16labels=1 not %run %t dfsan_create_label 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CREATE-LABEL
+// RUN: DFSAN_OPTIONS=fast16labels=1 not %run %t dfsan_get_label_info 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=GET-LABEL-INFO
+// RUN: DFSAN_OPTIONS=fast16labels=1 not %run %t dfsan_has_label_with_desc \
+// RUN:   2>&1 | FileCheck %s --check-prefix=HAS-LABEL-WITH-DESC
 //
 // Tests DFSAN_OPTIONS=fast16labels=1
 //
@@ -6,12 +13,26 @@
 
 #include <assert.h>
 #include <stdio.h>
+#include <string.h>
 
 int foo(int a, int b) {
   return a + b;
 }
 
-int main() {
+int main(int argc, char *argv[]) {
+  // Death tests for unsupported API usage.
+  const char *command = (argc < 2) ? "" : argv[1];
+  // CREATE-LABEL: FATAL: DataFlowSanitizer: dfsan_create_label is unsupported
+  if (strcmp(command, "dfsan_create_label") == 0)
+    dfsan_create_label("", NULL);
+  // GET-LABEL-INFO: FATAL: DataFlowSanitizer: dfsan_get_label_info is unsupported
+  if (strcmp(command, "dfsan_get_label_info") == 0)
+    dfsan_get_label_info(1);
+  // HAS-LABEL-WITH-DESC: FATAL: DataFlowSanitizer: dfsan_has_label_with_desc is unsupported
+  if (strcmp(command, "dfsan_has_label_with_desc") == 0)
+    dfsan_has_label_with_desc(1, "");
+
+  // Supported usage.
   int a = 10;
   int b = 20;
   dfsan_set_label(8, &a, sizeof(a));
@@ -22,4 +43,7 @@ int main() {
   dfsan_label l = dfsan_get_label(c);
   printf("C: 0x%x\n", l);
   assert(l == 520);  // OR of the other two labels.
+  assert(dfsan_has_label(l, 8));
+  assert(dfsan_has_label(l, 512));
+  assert(!dfsan_has_label(l, 1));
 }