This is the mail archive of the mailing list for the glibc project.

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

[PATCH] Don't divide by zero when trying to destroy an uninitialised barrier.

 nptl/pthread_barrier_destroy.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/nptl/pthread_barrier_destroy.c b/nptl/pthread_barrier_destroy.c
index 92d2027..d114084 100644
--- a/nptl/pthread_barrier_destroy.c
+++ b/nptl/pthread_barrier_destroy.c
@@ -36,6 +36,15 @@ pthread_barrier_destroy (pthread_barrier_t *barrier)
      they have exited as well.  To get the notification, pretend that we have
      reached the reset threshold.  */
   unsigned int count = bar->count;
+  /* For an initialised barrier, count must be greater than zero here.  An
+     uninitialised barrier may still have zero, however, and in this case it is
+     preferable to fail immediately rather than to invoke undefined behaviour
+     by dividing by zero on the next line.  (POSIX allows the implementation to
+     diagnose invalid state and return EINVAL in this case.)  */
+  if (__glibc_unlikely (count == 0))
+    return EINVAL;
   unsigned int max_in_before_reset = BARRIER_IN_THRESHOLD
                                   - BARRIER_IN_THRESHOLD % count;
   /* Relaxed MO sufficient because the program must have ensured that all

Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]