debug: make __read_chk a cancellation point (bug 29274)

The __read_chk function, as the implementation behind the fortified read
function, must be a cancellation point, thus it cannot use INLINE_SYSCALL.

1 files changed, 50 insertions, 0 deletions

diff --git a/debug/tst-read-chk-cancel.c b/debug/tst-read-chk-cancel.c
new file mode 100644
index 0000000000..7e06afb596
--- /dev/null
+++ b/debug/tst-read-chk-cancel.c
@@ -0,0 +1,50 @@
+/* Test that __read_chk is a cancellation point (BZ #29274)
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <stdint.h>
+#include <support/xunistd.h>
+#include <support/xthread.h>
+
+static int pipe_fds[2];
+static pthread_barrier_t barrier;
+
+static void *
+read_thread (void *n)
+{
+  xpthread_barrier_wait (&barrier);
+  char c;
+  /* This call should be forwarded to __read_chk because the buffer size
+     is known, but the read length is non-constant.  */
+  if (read (pipe_fds[0], &c, (uintptr_t) n) != 1)
+    return (void *) -1L;
+  return 0;
+}
+
+static int
+do_test (void)
+{
+  xpthread_barrier_init (&barrier, 0, 2);
+  xpipe (pipe_fds);
+  pthread_t thr = xpthread_create (0, read_thread, (void *) 1L);
+  xpthread_barrier_wait (&barrier);
+  xpthread_cancel (thr);
+  xpthread_join (thr);
+  return 0;
+}
+
+#include <support/test-driver.c>