More string interceptors: strstr, strcasestr, strspn, strcspn, strpbrk

[m.guseva]

Summary

This is a patch for Issue 346: moar string interceptors: strstr, strcasestr, strcspn, strpbrk.
The initial patch for this issue was: http://reviews.llvm.org/D6056. But it was abandoned and splitted in two parts: New "strict_string_checks" run-time flag and this one.

[dvyukov]

lib/sanitizer_common/sanitizer_common_interceptors.inc

274

delete empty line (two consequent empty lines)

276

delete empty line (that's how it is written everywhere in this file)

282

Is "r - s1 + len2 + 1" correct?
I think it should be "r - s1 + len2", because strstr can read only len2 bytes to find a match.

284

I am not sure such complex computations are necessary. People should not rely on such things.
If anything, I think, the fifth argument should be 1, because if I call strstr("aaaaaaaaaaaa", "bcdef") I can "expect" that the function will read only the first symbol "b" from the second string.

288

add parens around COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED

293

drop {}

299

#define INIT_STRSTR \

COMMON_INTERCEPT_FUNCTION(strstr); \
COMMON_INTERCEPT_FUNCTION(strcasestr);

and move below

311

remove

315

remove

317

delete empty line

320

delete empty line

327

I don't believe this is necessary. Make it just:
READ_RANGE(s2, REAL(strlen)(s2) + 1);

333

move below (see how it is formatted in other case in this file)

342

I don't believe this complex code is necessary. Make it just:
READ_RANGE(s2, REAL(strlen)(s2) + 1);

4956

delete

lib/sanitizer_common/sanitizer_flags.inc

157

do we need all these additional flags? why?

lib/sanitizer_common/sanitizer_platform_interceptors.h

58

this is unused, delete

60

delete

[m.guseva]

lib/sanitizer_common/sanitizer_common_interceptors.inc

284

Do you mean the following: (ctx, s2, len2, r ? len2 + 1 : (len2 <= len1 ? 1 : len1 + 1)); ?
In that case we may not check real read of bigger length from s2 in case there is some not null intersection of s1 and s2.
The most accurate result would be if repeat explicitly strstr computations and find that real length. But I've just added non-strict check assuming the worst case.

327

Why not?
Indeed we don't need to read the full length of s2. User may expect it in non-strict case.

342

The same - please explain. My intention was to avoid strict checks when possible.

lib/sanitizer_common/sanitizer_flags.inc

157

It was discussed in initial patch for this http://reviews.llvm.org/D6056#92330: glider suggested to have individual flags. I agree, it's more flexible.

lib/sanitizer_common/sanitizer_platform_interceptors.h

58

It's my bug, SANITIZER_INTERCEPT_STRCASESTR must be used in sanitizer_common_interceptors.inc cause indeed there is no strcasestr on Windows. I'll fix it.

The rest is always 1 so I agree it could be removed. I wonder why there are other defines allways equal to 1 in sanitizer_platform_interceptors.h?

[dvyukov]

lib/sanitizer_common/sanitizer_common_interceptors.inc

284

The worst case is strlen(s2)+1. An implementation is allowed to read that much.
The non-strict mode should consider the _best_ case if anything. But I would just delete this complexity and use strlen.

327

Because these are very complex expressions with lots of corner cases and potential off-by-ones.
User should not expect that the function won't read the whole string. There are not such guarantees in the documentation. Documentation refers to arguments as to strings. Strings are addressable zero-terminated regions of memory.

lib/sanitizer_common/sanitizer_flags.inc

157

Okay
I am not very strong about this

lib/sanitizer_common/sanitizer_platform_interceptors.h

58

I mean delete them because they are unused, not because they are always 1.
I guess we have always 1 defines for flexibility and consistency.

[m.guseva]

lib/sanitizer_common/sanitizer_common_interceptors.inc

284

The non-strict mode should consider the _best_ case if anything.

I understand the non-strict mode as ability to check less then full string length when it's possible. It shouldn't rely on best case, it should check at least as much as needed for getting the result. I think it's better to check more bytes than to miss incorrect read. If proposed read check is inaccurate I agree it's better to replace with full length check.

327

User should not expect that the function won't read the whole string. There are not such guarantees in the documentation.

The "strict_string_checks" flag was introduced exactly cause user may expect such behaviour despite of documentation. Which are corner cases here? Can I just cover them?

[ygribov]

lib/sanitizer_common/sanitizer_common_interceptors.inc

327

I guess Dmitry means that there is a tradeoff between functionality and code complexity. And he'd prefer to drop overly complex checks in favor of simplicity.

[dvyukov]

lib/sanitizer_common/sanitizer_common_interceptors.inc

327

Yes, what Yury said. "r ? internal_strchr(s2, *r) - s2 + 1 : *s1 ? REAL(strlen)(s2) + 1 : 0" is complex without providing any obvious benefit.

If anything, non-strict mode check at _most_ (rather than at least) as much as needed for getting the result. But what is required to get the result? It depends on the implementation of the function in libc.
For example, I, as a user, can argue than strstr("aaaaaaaaaaaa", "bcdef") must read no more than 1 byte from the second string. While your non-strict implementation checks more, thus will cause a crash which looks non-legitimate to me.
The non-strict checks were introduced based on real cases that we observed and were unable to fix. Adding them proactively looks wrong to me. If a user hits such a case, then the first thing he should try is to fix the code (formally it is illegal). This should cover majority of the cases. If fixing the code is not possible, then he can use the flag to disable the interceptor. Meanwhile we can figure out whether we want to relax checking in the interceptor or not.

[m.guseva]

Hi,

I've uploaded new patch with fixes suggested by Dmitry. Could you please take a look? Thank you.

[dvyukov]

thanks, the code is now much easier to understand
LGTM

lib/sanitizer_common/sanitizer_common_interceptors.inc

276

remove whitespace after s2

318

please add strspn interceptor for completeness

[m.guseva]

Thank you. I've uploaded new patch with strspn interceptors added. I moved both strspn and strcspn under the same flag intercept_strspn and one macro SANITIZER_INTERCEPT_STRSPN.

[ygribov]

I'll submit tomorrow (if no objections from Dima) so that we are around to cope with bugs.

lib/sanitizer_common/sanitizer_common_interceptors.inc

 
 #define INIT_STRCASECMP COMMON_INTERCEPT_FUNCTION(strcasecmp)
 #define INIT_STRNCASECMP COMMON_INTERCEPT_FUNCTION(strncasecmp)
 #else
 #define INIT_STRCASECMP
 #define INIT_STRNCASECMP
 #endif
 
+#if SANITIZER_INTERCEPT_STRSTR || SANITIZER_INTERCEPT_STRCASESTR
+static inline void StrstrCheck(void *ctx, char *r, const char *s1,
+                               const char *s2 ) {
+    uptr len1 = REAL(strlen)(s1);
+    uptr len2 = REAL(strlen)(s2);
+    COMMON_INTERCEPTOR_READ_STRING_OF_LEN(ctx, s1, len1,
+                                          r ? r - s1 + len2 : len1 + 1);
+    COMMON_INTERCEPTOR_READ_RANGE(ctx, s2, len2 + 1);
+}
+#endif
+
+#if SANITIZER_INTERCEPT_STRSTR
+INTERCEPTOR(char*, strstr, const char *s1, const char *s2) {
+  if (COMMON_INTERCEPTOR_NOTHING_IS_INITIALIZED)
+    return internal_strstr(s1, s2);
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, strstr, s1, s2);
+  char *r = REAL(strstr)(s1, s2);
+  if (common_flags()->intercept_strstr)
+    StrstrCheck(ctx, r, s1, s2);
+  return r;
+}
+
+#define INIT_STRSTR COMMON_INTERCEPT_FUNCTION(strstr);
+#else
+#define INIT_STRSTR
+#endif
+
+#if SANITIZER_INTERCEPT_STRCASESTR
+INTERCEPTOR(char*, strcasestr, const char *s1, const char *s2) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, strcasestr, s1, s2);
+  char *r = REAL(strcasestr)(s1, s2);
+  if (common_flags()->intercept_strstr)
+    StrstrCheck(ctx, r, s1, s2);
+  return r;
+}
+
+#define INIT_STRCASESTR COMMON_INTERCEPT_FUNCTION(strcasestr);
+#else
+#define INIT_STRCASESTR
+#endif
+
+#if SANITIZER_INTERCEPT_STRCSPN
+INTERCEPTOR(SIZE_T, strcspn, const char *s1, const char *s2) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, strcspn, s1, s2);
+  SIZE_T r = REAL(strcspn)(s1, s2);
+  if (common_flags()->intercept_strcspn) {
+    COMMON_INTERCEPTOR_READ_RANGE(ctx, s2, REAL(strlen)(s2) + 1);
+    COMMON_INTERCEPTOR_READ_STRING(ctx, s1, r + 1);
+  }
+  return r;
+}
+
+#define INIT_STRCSPN COMMON_INTERCEPT_FUNCTION(strcspn);
+#else
+#define INIT_STRCSPN
+#endif
+
+#if SANITIZER_INTERCEPT_STRPBRK
+INTERCEPTOR(char *, strpbrk, const char *s1, const char *s2) {
+  void *ctx;
+  COMMON_INTERCEPTOR_ENTER(ctx, strpbrk, s1, s2);
+  char *r = REAL(strpbrk)(s1, s2);
+  if (common_flags()->intercept_strpbrk) {
+    COMMON_INTERCEPTOR_READ_RANGE(ctx, s2, REAL(strlen)(s2) + 1);
+    COMMON_INTERCEPTOR_READ_STRING(ctx, s1,
+        r ? r - s1 + 1 : REAL(strlen)(s1) + 1);
+  }
+  return r;
+}
+
+#define INIT_STRPBRK COMMON_INTERCEPT_FUNCTION(strpbrk);
+#else
+#define INIT_STRPBRK
+#endif
+
 #if SANITIZER_INTERCEPT_MEMCHR
 INTERCEPTOR(void*, memchr, const void *s, int c, SIZE_T n) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER(ctx, memchr, s, c, n);
   void *res = REAL(memchr)(s, c, n);
   uptr len = res ? (char *)res - (const char *)s + 1 : n;
   COMMON_INTERCEPTOR_READ_RANGE(ctx, s, len);
   return res;
static void InitializeCommonInterceptors() {
   static u64 metadata_mem[sizeof(MetadataHashMap) / sizeof(u64) + 1];
   interceptor_metadata_map = new((void *)&metadata_mem) MetadataHashMap();
 
   INIT_TEXTDOMAIN;
   INIT_STRCMP;
   INIT_STRNCMP;
   INIT_STRCASECMP;
   INIT_STRNCASECMP;
+  INIT_STRSTR;
+  INIT_STRCASESTR;
+  INIT_STRCSPN;
+  INIT_STRPBRK;
   INIT_MEMCHR;
   INIT_MEMRCHR;
   INIT_READ;
   INIT_PREAD;
   INIT_PREAD64;
   INIT_READV;
   INIT_PREADV;
   INIT_PREADV64;

lib/sanitizer_common/sanitizer_flags.inc

 COMMON_FLAG(const char *, stack_trace_format, "DEFAULT",
             "Format string used to render stack frames. "
             "See sanitizer_stacktrace_printer.h for the format description. "
             "Use DEFAULT to get default format.")
 COMMON_FLAG(bool, no_huge_pages_for_shadow, true,
             "If true, the shadow is not allowed to use huge pages. ")
 COMMON_FLAG(bool, strict_string_checks, false,
             "If set check that string arguments are properly null-terminated")
+COMMON_FLAG(bool, intercept_strstr, true,
+            "If set, uses custom wrappers for strstr and strcasestr functions "
+            "to find more errors.")
+COMMON_FLAG(bool, intercept_strcspn, true,
+            "If set, uses custom wrappers for strcspn function "
+            "to find more errors.")
+COMMON_FLAG(bool, intercept_strpbrk, true,
+            "If set, uses custom wrappers for strpbrk function "
+            "to find more errors.")

lib/sanitizer_common/sanitizer_platform_interceptors.h

 
 #if SANITIZER_IOS
 # define SI_IOS 1
 #else
 # define SI_IOS 0
 #endif
 
 #define SANITIZER_INTERCEPT_STRCMP 1
+#define SANITIZER_INTERCEPT_STRSTR 1
+#define SANITIZER_INTERCEPT_STRCASESTR SI_NOT_WINDOWS
+#define SANITIZER_INTERCEPT_STRCSPN 1
+#define SANITIZER_INTERCEPT_STRPBRK 1
 #define SANITIZER_INTERCEPT_TEXTDOMAIN SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_STRCASECMP SI_NOT_WINDOWS
 #define SANITIZER_INTERCEPT_MEMCHR 1
 #define SANITIZER_INTERCEPT_MEMRCHR SI_FREEBSD || SI_LINUX
 
 #define SANITIZER_INTERCEPT_READ   SI_NOT_WINDOWS
 #define SANITIZER_INTERCEPT_PREAD  SI_NOT_WINDOWS
 #define SANITIZER_INTERCEPT_WRITE  SI_NOT_WINDOWS

lib/tsan/rtl/tsan_interceptors.cc

 TSAN_INTERCEPTOR(char*, strncpy, char *dst, char *src, uptr n) {
   SCOPED_TSAN_INTERCEPTOR(strncpy, dst, src, n);
   uptr srclen = internal_strnlen(src, n);
   MemoryAccessRange(thr, pc, (uptr)dst, n, true);
   MemoryAccessRange(thr, pc, (uptr)src, min(srclen + 1, n), false);
   return REAL(strncpy)(dst, src, n);
 }
 
-TSAN_INTERCEPTOR(const char*, strstr, const char *s1, const char *s2) {
-  SCOPED_TSAN_INTERCEPTOR(strstr, s1, s2);
-  const char *res = REAL(strstr)(s1, s2);
-  uptr len1 = internal_strlen(s1);
-  uptr len2 = internal_strlen(s2);
-  MemoryAccessRange(thr, pc, (uptr)s1, len1 + 1, false);
-  MemoryAccessRange(thr, pc, (uptr)s2, len2 + 1, false);
-  return res;
-}
-
 TSAN_INTERCEPTOR(char*, strdup, const char *str) {
   SCOPED_TSAN_INTERCEPTOR(strdup, str);
   // strdup will call malloc, so no instrumentation is required here.
   return REAL(strdup)(str);
 }
 
 static bool fix_mmap_addr(void **addr, long_t sz, int flags) {
   if (*addr) {
#endif
   TSAN_INTERCEPT(memcpy);
   TSAN_INTERCEPT(memmove);
   TSAN_INTERCEPT(memcmp);
   TSAN_INTERCEPT(strchr);
   TSAN_INTERCEPT(strchrnul);
   TSAN_INTERCEPT(strrchr);
   TSAN_INTERCEPT(strcpy);  // NOLINT
   TSAN_INTERCEPT(strncpy);
-  TSAN_INTERCEPT(strstr);
   TSAN_INTERCEPT(strdup);
 
   TSAN_INTERCEPT(pthread_create);
   TSAN_INTERCEPT(pthread_join);
   TSAN_INTERCEPT(pthread_detach);
 
   TSAN_INTERCEPT_VER(pthread_cond_init, "GLIBC_2.3.2");
   TSAN_INTERCEPT_VER(pthread_cond_signal, "GLIBC_2.3.2");

test/asan/TestCases/strcasestr-1.c

+// Test haystack overflow in strcasestr function
+// RUN: %clang_asan %s -o %t && ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+// Test intercept_strstr asan option
+// RUN: ASAN_OPTIONS=intercept_strstr=false %run %t 2>&1
+
+// There's no interceptor for strcasestr on Windows
+// XFAIL: win32
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  char *r = 0;
+  char s2[] = "c";
+  char s1[] = {'a', 'b'};
+  char s3 = 0;
+  r = strcasestr(s1, s2);
+  // CHECK:'s{{[1|3]}}' <== Memory access at offset {{[0-9]+ .*}}flows this variable
+  assert(r == 0);
+  return 0;
+}

test/asan/TestCases/strcasestr-2.c

+// Test needle overflow in strcasestr function
+// RUN: %clang_asan %s -o %t && ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+// Test intercept_strstr asan option
+// RUN: ASAN_OPTIONS=intercept_strstr=false %run %t 2>&1
+
+// There's no interceptor for strcasestr on Windows
+// XFAIL: win32
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  char *r = 0;
+  char s1[] = "ab";
+  char s2[] = {'c'};
+  char s3 = 0;
+  r = strcasestr(s1, s2);
+  assert(r == 0);
+  // CHECK:'s{{[2|3]}}' <== Memory access at offset {{[0-9]+ .*}}flows this variable
+  return 0;
+}

test/asan/TestCases/strcasestr_strict.c

+// Test strict_string_checks option in strcasestr function
+// RUN: %clang_asan %s -o %t && %run %t 2>&1
+// RUN: ASAN_OPTIONS=strict_string_checks=false %run %t 2>&1
+// RUN: ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+// There's no interceptor for strcasestr on Windows
+// XFAIL: win32
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  size_t size = 100;
+  char *s1 = (char*)malloc(size);
+  char *s2 = (char*)malloc(size);
+  memset(s1, 'o', size);
+  memset(s2, 'O', size);
+  s2[size - 1]='\0';
+  char* r = strcasestr(s1, s2);
+  // CHECK: {{.*ERROR: AddressSanitizer: heap-buffer-overflow on address}}
+  // CHECK: READ of size 101
+  assert(r == s1);
+  free(s1);
+  free(s2);
+  return 0;
+}

test/asan/TestCases/strcspn-1.c

+// Test string s1 overflow in strcspn function
+// RUN: %clang_asan %s -o %t && ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+// Test intercept_strcspn asan option
+// RUN: ASAN_OPTIONS=intercept_strcspn=false %run %t 2>&1
+
+#include <assert.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  size_t r;
+  char s2[] = "ab";
+  char s1[] = {'c', 'd'};
+  char s3 = 0;
+  r = strcspn(s1, s2);
+  // CHECK:'s{{[1|3]}}' <== Memory access at offset {{[0-9]+ .*}}flows this variable
+  assert(r >= sizeof(s1));
+  return 0;
+}

test/asan/TestCases/strcspn-2.c

+// Test stopset overflow in strcspn function
+// RUN: %clang_asan %s -o %t && ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+// Test intercept_strcspn asan option
+// RUN: ASAN_OPTIONS=intercept_strcspn=false %run %t 2>&1
+
+#include <assert.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  size_t r;
+  char s1[] = "ab";
+  char s2[] = {'c', 'd'};
+  char s3 = 0;
+  r = strcspn(s1, s2);
+  // CHECK:'s{{[2|3]}}' <== Memory access at offset {{[0-9]+ .*}}flows this variable
+  assert(r == sizeof(s1) - 1);
+  return 0;
+}

test/asan/TestCases/strcspn_strict.c

+// Test strict_string_checks option in strcspn function
+// RUN: %clang_asan %s -o %t && %run %t 2>&1
+// RUN: ASAN_OPTIONS=strict_string_checks=false %run %t 2>&1
+// RUN: ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  size_t size = 100;
+  char fill = 'o';
+  char *s1 = (char*)malloc(size);
+  char *s2 = (char*)malloc(size);
+  memset(s1, fill, size);
+  s1[0] = 'z';
+  memset(s2, fill, size);
+  s2[size-1] = '\0';
+  size_t r = strcspn(s1, s2);
+  // CHECK: {{.*ERROR: AddressSanitizer: heap-buffer-overflow on address}}
+  // CHECK: READ of size 101
+  assert(r == 1);
+  free(s1);
+  free(s2);
+  return 0;
+}

test/asan/TestCases/strpbrk-1.c

+// Test string s1 overflow in strpbrk function
+// RUN: %clang_asan %s -o %t && ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+// Test intercept_strpbrk asan option
+// RUN: ASAN_OPTIONS=intercept_strpbrk=false %run %t 2>&1
+
+#include <assert.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  char *r;
+  char s2[] = "ab";
+  char s1[] = {'c', 'd'};
+  char s3[] = "a";
+  r = strpbrk(s1, s2);
+  // CHECK:'s{{[1|3]}}' <== Memory access at offset {{[0-9]+ .*}}flows this variable
+  assert(r <= s3);
+  return 0;
+}

test/asan/TestCases/strpbrk-2.c

+// Test stopset overflow in strpbrk function
+// RUN: %clang_asan %s -o %t && ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+// Test intercept_strpbrk asan option
+// RUN: ASAN_OPTIONS=intercept_strpbrk=false %run %t 2>&1
+
+#include <assert.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  char *r;
+  char s1[] = "a";
+  char s2[] = {'b', 'c'};
+  char s3 = 0;
+  r = strpbrk(s1, s2);
+  // CHECK:'s{{[2|3]}}' <== Memory access at offset {{[0-9]+ .*}}flows this variable
+  assert(r == (r ? s1 : 0));
+  return 0;
+}

test/asan/TestCases/strpbrk_strict.c

+// Test strict_string_checks option in strpbrk function
+// RUN: %clang_asan %s -o %t && %run %t 2>&1
+// RUN: ASAN_OPTIONS=strict_string_checks=false %run %t 2>&1
+// RUN: ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  size_t size = 100;
+  char fill = 'o';
+  char *s1 = (char*)malloc(size);
+  char *s2 = (char*)malloc(2);
+  memset(s1, fill, size);
+  s2[0] = fill;
+  s2[1]='\0';
+  char* r = strpbrk(s1, s2);
+  // CHECK: {{.*ERROR: AddressSanitizer: heap-buffer-overflow on address}}
+  // CHECK: READ of size 101
+  assert(r == s1);
+  free(s1);
+  free(s2);
+  return 0;
+}

test/asan/TestCases/strstr-1.c

+// Test haystack overflow in strstr function
+// RUN: %clang_asan %s -o %t && ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+// Test intercept_strstr asan option
+// RUN: ASAN_OPTIONS=intercept_strstr=false %run %t 2>&1
+
+#include <assert.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  char *r = 0;
+  char s2[] = "c";
+  char s1[] = {'a', 'b'};
+  char s3 = 0;
+  r = strstr(s1, s2);
+  // CHECK:'s{{[1|3]}}' <== Memory access at offset {{[0-9]+ .*}}flows this variable
+  assert(r == 0);
+  return 0;
+}

test/asan/TestCases/strstr-2.c

+// Test needle overflow in strstr function
+// RUN: %clang_asan %s -o %t && ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+// Test intercept_strstr asan option
+// RUN: ASAN_OPTIONS=intercept_strstr=false %run %t 2>&1
+
+#include <assert.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  char *r = 0;
+  char s1[] = "ab";
+  char s2[] = {'c'};
+  char s3 = 0;
+  r = strstr(s1, s2);
+  // CHECK:'s{{[2|3]}}' <== Memory access at offset {{[0-9]+ .*}}flows this variable
+  assert(r == 0);
+  return 0;
+}

test/asan/TestCases/strstr_strict.c

+// Test strict_string_checks option in strstr function
+// RUN: %clang_asan %s -o %t && %run %t 2>&1
+// RUN: ASAN_OPTIONS=strict_string_checks=false %run %t 2>&1
+// RUN: ASAN_OPTIONS=strict_string_checks=true not %run %t 2>&1 | FileCheck %s
+
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  size_t size = 100;
+  char fill = 'o';
+  char *s1 = (char*)malloc(size);
+  char *s2 = (char*)malloc(size);
+  memset(s1, fill, size);
+  memset(s2, fill, size);
+  s2[size - 1]='\0';
+  char* r = strstr(s1, s2);
+  // CHECK: {{.*ERROR: AddressSanitizer: heap-buffer-overflow on address}}
+  // CHECK: READ of size 101
+  assert(r == s1);
+  free(s1);
+  free(s2);
+  return 0;
+}

test/sanitizer_common/TestCases/strcasestr.c

+// RUN: %clang %s -o %t && %run %t 2>&1
+
+// There's no interceptor for strcasestr on Windows
+// XFAIL: win32
+
+#define _GNU_SOURCE
+#include <assert.h>
+#include <string.h>
+int main(int argc, char **argv) {
+  char *r = 0;
+  char s1[] = "aB";
+  char s2[] = "b";
+  r = strcasestr(s1, s2);
+  assert(r == s1 + 1);
+  return 0;
+}

test/sanitizer_common/TestCases/strcspn.c

+// RUN: %clang %s -o %t && %run %t 2>&1
+
+#include <assert.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+  size_t r;
+  char s1[] = "ad";
+  char s2[] = "cd";
+  r = strcspn(s1, s2);
+  assert(r == 1);
+  return 0;
+}

test/sanitizer_common/TestCases/strpbrk.c

+// RUN: %clang %s -o %t && %run %t 2>&1
+
+#include <assert.h>
+#include <string.h>
+
+
+int main(int argc, char **argv) {
+  char *r = 0;
+  char s1[] = "ad";
+  char s2[] = "cd";
+  r = strpbrk(s1, s2);
+  assert(r == s1 + 1);
+  return 0;
+}

test/sanitizer_common/TestCases/strstr.c

+// RUN: %clang %s -o %t && %run %t 2>&1
+
+#include <assert.h>
+#include <string.h>
+int main(int argc, char **argv) {
+  char *r = 0;
+  char s1[] = "ab";
+  char s2[] = "b";
+  r = strstr(s1, s2);
+  assert(r == s1 + 1);
+  return 0;
+}