[llvm-commits] [ASan] Define an internal implementation of strchr to make stack OOB tests pass (issue 5668047)

[timurrrr at google.com]

Reviewers: kcc1,

Message:
Hi Kostya,

Can you please review this small patch?

Thanks!

Description:
Define an internal implementation of strchr to make stack OOB tests pass

Please review this at http://codereview.appspot.com/5668047/

Affected files:
   M lib/asan/asan_interceptors.cc
   M lib/asan/asan_rtl.cc


Index: lib/asan/asan_interceptors.cc
diff --git a/lib/asan/asan_interceptors.cc b/lib/asan/asan_interceptors.cc
index  
b2d437590e9bccbdccf8f0c8a23c62c582e679e1..23a5ac94a0f853b56c67338dcfe2ebc6cdcd7155  
100644
--- a/lib/asan/asan_interceptors.cc
+++ b/lib/asan/asan_interceptors.cc
@@ -109,6 +109,15 @@ size_t internal_strlen(const char *s) {
    return i;
  }

+char* internal_strchr(const char *s, int c) {
+  for (size_t i = 0; ; ++i) {
+    if (s[i] == (char)c)
+      return (char*)&s[i];
+    if (s[i] == 0)
+      return NULL;
+  }
+}
+
  size_t internal_strnlen(const char *s, size_t maxlen) {
  #ifndef __APPLE__
    if (REAL(strnlen) != NULL) {
@@ -578,6 +587,7 @@ void InitializeAsanInterceptors() {
    // functions for now.
    REAL(memcpy) = memcpy;
    REAL(memset) = memset;
+  REAL(strchr) = internal_strchr;
  #endif

  #ifdef __APPLE__
Index: lib/asan/asan_rtl.cc
diff --git a/lib/asan/asan_rtl.cc b/lib/asan/asan_rtl.cc
index  
4d3eb6e377078ee2e849f3012e5d439509e965e1..b429a7814790ce345c429072579104e8c0b47fbe  
100644
--- a/lib/asan/asan_rtl.cc
+++ b/lib/asan/asan_rtl.cc
@@ -159,6 +159,7 @@ static bool DescribeStackAddress(uintptr_t addr,  
uintptr_t access_size) {
    // where alloc_i looks like "offset size len ObjectName ".
    CHECK(frame_descr);
    // Report the function name and the offset.
+  CHECK(REAL(strchr));
    const char *name_end = REAL(strchr)(frame_descr, ' ');
    CHECK(name_end);
    buf[0] = 0;