[dfsan] Add custom function for pthread_create.

[eugenis]

lib/dfsan/dfsan_custom.cc

285

I'm slightly confused. This would be the label for the thread return value, right? Don't you need to keep it somewhere for pthread_join()?

lib/dfsan/lit_tests/custom.c

138

You are not testing any label-passing behavior of pthread_create() at all.

[pcc]

• Check the label of the callback argument

lib/dfsan/dfsan_custom.cc

285

I think that propagating labels through pthread_create and pthread_join can be done in a separate change. But for now I am fixing the more fundamental bug that the pthread_create callback argument can receive an invalid nonzero label due to an ABI mismatch.

lib/dfsan/lit_tests/custom.c

138

I now test that the argument is unlabelled.

[eugenis]

LGTM

[pcc]

Closed by commit rL189502 (authored by @pcc).

lib/dfsan/dfsan_custom.cc

 #include "sanitizer/dfsan_interface.h"
 #include "sanitizer_common/sanitizer_internal_defs.h"
 #include "sanitizer_common/sanitizer_linux.h"
 
 #include "dfsan/dfsan.h"
 
 #include <ctype.h>
 #include <dlfcn.h>
+#include <pthread.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <time.h>
 #include <unistd.h>
 
 using namespace __dfsan;
__dfsw_dlopen(const char *filename, int flag, dfsan_label filename_label,
               dfsan_label flag_label, dfsan_label *ret_label) {
   link_map *map = (link_map *)dlopen(filename, flag);
   if (map)
     ForEachMappedRegion(map, unpoison);
   *ret_label = 0;
   return (void *)map;
 }
 
+struct pthread_create_info {
+  void *(*start_routine_trampoline)(void *, void *, dfsan_label, dfsan_label *);
+  void *start_routine;
+  void *arg;
+};
+
+static void *pthread_create_cb(void *p) {
+  pthread_create_info pci(*(pthread_create_info *)p);
+  free(p);
+  dfsan_label ret_label;
+  return pci.start_routine_trampoline(pci.start_routine, pci.arg, 0,
+                                      &ret_label);
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_pthread_create(
+    pthread_t *thread, const pthread_attr_t *attr,
+    void *(*start_routine_trampoline)(void *, void *, dfsan_label,
+                                      dfsan_label *),
+    void *start_routine, void *arg, dfsan_label thread_label,
+    dfsan_label attr_label, dfsan_label start_routine_label,
+    dfsan_label arg_label, dfsan_label *ret_label) {
+  pthread_create_info *pci =
+      (pthread_create_info *)malloc(sizeof(pthread_create_info));
+  pci->start_routine_trampoline = start_routine_trampoline;
+  pci->start_routine = start_routine;
+  pci->arg = arg;
+  int rv = pthread_create(thread, attr, pthread_create_cb, (void *)pci);
+  if (rv != 0)
+    free(pci);
+  *ret_label = 0;
+  return rv;
+}
+
 }

lib/dfsan/done_abilist.txt

 fun:strncasecmp=custom
 fun:strchr=custom
 fun:strlen=custom
 fun:calloc=custom
 fun:dlopen=custom
 fun:read=custom
 fun:pread=custom
 fun:clock_gettime=custom
+fun:pthread_create=custom
 
 # TODO: custom
 fun:snprintf=discard
 fun:asprintf=discard
 fun:qsort=discard
 fun:strtoll=discard
 fun:strtoull=discard
 fun:sigemptyset=discard
 fun:sigaction=discard
 fun:gettimeofday=discard

lib/dfsan/lit_tests/custom.c

 // RUN: %clang_dfsan -m64 %s -o %t && %t
 // RUN: %clang_dfsan -mllvm -dfsan-args-abi -m64 %s -o %t && %t
 
 // Tests custom implementations of various libc functions.
 
 #include <sanitizer/dfsan_interface.h>
 #include <assert.h>
+#include <pthread.h>
 #include <string.h>
 #include <stdlib.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
 
+void *ptcb(void *p) {
+  assert(p == (void *)1);
+  return (void *)2;
+}
+
 int main(void) {
   int i = 1;
   dfsan_label i_label = dfsan_create_label("i", 0);
   dfsan_set_label(i_label, &i, sizeof(i));
 
   int j = 2;
   dfsan_label j_label = dfsan_create_label("j", 0);
   dfsan_set_label(j_label, &j, sizeof(j));
int main(void) {
   fd = open("/bin/sh", O_RDONLY);
   buf[0] = i;
   buf[15] = j;
   rv = pread(fd, buf, sizeof(buf), 0);
   assert(rv == sizeof(buf));
   assert(dfsan_get_label(buf[0]) == 0);
   assert(dfsan_get_label(buf[15]) == 0);
 
+  pthread_t pt;
+  pthread_create(&pt, 0, ptcb, (void *)1);
+  void *cbrv;
+  pthread_join(pt, &cbrv);
+  assert(cbrv == (void *)2);
+
   return 0;
 }