fix stdio lock dependency on read-after-free not faulting

[musl] / src / stdio / fflush.c

diff --git a/src/stdio/fflush.c b/src/stdio/fflush.c
index 3f462c8..bf1e843 100644 (file)
--- a/src/stdio/fflush.c
+++ b/src/stdio/fflush.c
@@ -1,11 +1,33 @@
 #include "stdio_impl.h"
 
-static int __fflush_unlocked(FILE *f)
+/* stdout.c will override this if linked */
+static FILE *volatile dummy = 0;
+weak_alias(dummy, __stdout_used);
+
+int fflush(FILE *f)
 {
+       if (!f) {
+               int r = __stdout_used ? fflush(__stdout_used) : 0;
+
+               for (f=*__ofl_lock(); f; f=f->next) {
+                       FLOCK(f);
+                       if (f->wpos > f->wbase) r |= fflush(f);
+                       FUNLOCK(f);
+               }
+               __ofl_unlock();
+
+               return r;
+       }
+
+       FLOCK(f);
+
        /* If writing, flush output */
        if (f->wpos > f->wbase) {
                f->write(f, 0, 0);
-               if (!f->wpos) return EOF;
+               if (!f->wpos) {
+                       FUNLOCK(f);
+                       return EOF;
+               }
        }
 
        /* If reading, sync position, per POSIX */
@@ -15,34 +37,8 @@ static int __fflush_unlocked(FILE *f)
        f->wpos = f->wbase = f->wend = 0;
        f->rpos = f->rend = 0;
 
+       FUNLOCK(f);
        return 0;
 }
 
-/* stdout.c will override this if linked */
-static FILE *volatile dummy = 0;
-weak_alias(dummy, __stdout_used);
-
-int fflush(FILE *f)
-{
-       int r;
-
-       if (f) {
-               FLOCK(f);
-               r = __fflush_unlocked(f);
-               FUNLOCK(f);
-               return r;
-       }
-
-       r = __stdout_used ? fflush(__stdout_used) : 0;
-
-       for (f=*__ofl_lock(); f; f=f->next) {
-               FLOCK(f);
-               if (f->wpos > f->wbase) r |= __fflush_unlocked(f);
-               FUNLOCK(f);
-       }
-       __ofl_unlock();
-       
-       return r;
-}
-
-weak_alias(__fflush_unlocked, fflush_unlocked);
+weak_alias(fflush, fflush_unlocked);