[msan] Intercept qsort, qsort_r.

Summary:
This fixes qsort-related false positives with glibc-2.27.
I'm not entirely sure why they did not show up with the earlier
versions; the code seems similar enough.

Reviewers: vitalybuka

Subscribers: #sanitizers, llvm-commits

Tags: #sanitizers, #llvm

Differential Revision: https://reviews.llvm.org/D71740

1 files changed, 73 insertions, 0 deletions

diff --git a/compiler-rt/test/msan/qsort.cpp b/compiler-rt/test/msan/qsort.cpp
new file mode 100644
index 00000000000..eb869701186
--- /dev/null
+++ b/compiler-rt/test/msan/qsort.cpp
@@ -0,0 +1,73 @@
+// RUN: %clangxx_msan -O0 -g %s -o %t && %run %t
+
+#include <assert.h>
+#include <errno.h>
+#include <glob.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <sanitizer/msan_interface.h>
+
+constexpr size_t kSize1 = 27;
+constexpr size_t kSize2 = 7;
+
+bool seen2;
+
+void dummy(long a, long b, long c, long d, long e) {}
+
+void poison_stack_and_param() {
+  char x[10000];
+  int y;
+  dummy(y, y, y, y, y);
+}
+
+__attribute__((always_inline)) int cmp(long a, long b) {
+  if (a < b)
+    return -1;
+  else if (a > b)
+    return 1;
+  else
+    return 0;
+}
+
+int compar2(const void *a, const void *b) {
+  assert(a);
+  assert(b);
+  __msan_check_mem_is_initialized(a, sizeof(long));
+  __msan_check_mem_is_initialized(b, sizeof(long));
+  seen2 = true;
+  poison_stack_and_param();
+  return cmp(*(long *)a, *(long *)b);
+}
+
+int compar1(const void *a, const void *b) {
+  assert(a);
+  assert(b);
+  __msan_check_mem_is_initialized(a, sizeof(long));
+  __msan_check_mem_is_initialized(b, sizeof(long));
+
+  long *p = new long[kSize2];
+  // kind of random
+  for (int i = 0; i < kSize2; ++i)
+    p[i] = i * 2 + (i % 3 - 1) * 3;
+  qsort(p, kSize1, sizeof(long), compar2);
+  __msan_check_mem_is_initialized(p, sizeof(long) * kSize2);
+  delete[] p;
+
+  poison_stack_and_param();
+  return cmp(*(long *)a, *(long *)b);
+}
+
+int main(int argc, char *argv[]) {
+  long *p = new long[kSize1];
+  // kind of random
+  for (int i = 0; i < kSize1; ++i)
+    p[i] = i * 2 + (i % 3 - 1) * 3;
+  poison_stack_and_param();
+  qsort(p, kSize1, sizeof(long), compar1);
+  __msan_check_mem_is_initialized(p, sizeof(long) * kSize1);
+  assert(seen2);
+  delete[] p;
+  return 0;
+}