prevent CNAME/PTR parsing from reading data past the response end

[musl] / src / stdio / __lockfile.c

diff --git a/src/stdio/__lockfile.c b/src/stdio/__lockfile.c
index 6ebf620..0f60a14 100644 (file)
--- a/src/stdio/__lockfile.c
+++ b/src/stdio/__lockfile.c
@@ -3,16 +3,21 @@
 
 int __lockfile(FILE *f)
 {
-       int owner, tid = __pthread_self()->tid;
-       if (f->lock == tid)
+       int owner = f->lock, tid = __pthread_self()->tid;
+       if ((owner & ~MAYBE_WAITERS) == tid)
                return 0;
-       while ((owner = a_cas(&f->lock, 0, tid)))
-               __wait(&f->lock, &f->waiters, owner, 1);
-       return f->lockcount = 1;
+       owner = a_cas(&f->lock, 0, tid);
+       if (!owner) return 1;
+       while ((owner = a_cas(&f->lock, 0, tid|MAYBE_WAITERS))) {
+               if ((owner & MAYBE_WAITERS) ||
+                   a_cas(&f->lock, owner, owner|MAYBE_WAITERS)==owner)
+                       __futexwait(&f->lock, owner|MAYBE_WAITERS, 1);
+       }
+       return 1;
 }
 
 void __unlockfile(FILE *f)
 {
-       a_store(&f->lock, 0);
-       if (f->waiters) __wake(&f->lock, 1, 1);
+       if (a_swap(&f->lock, 0) & MAYBE_WAITERS)
+               __wake(&f->lock, 1, 1);
 }