vt: selection, push console lock down

commit 4b70dd57a15d2f4685ac6e38056bad93e81e982f upstream.

We need to nest the console lock in sel_lock, so we have to push it down
a bit. Fortunately, the callers of set_selection_* just lock the console
lock around the function call. So moving it down is easy.

In the next patch, we switch the order.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Fixes: 07e6124a1a46 ("vt: selection, close sel_buffer race")
Link: https://lore.kernel.org/r/20200228115406.5735-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/tty/vt/selection.c b/drivers/tty/vt/selection.c
index 4f7875cf99bd793c5a776ad24faefd1862ccb799..f74ce94a08ce26c50a9fa74af9a5c75aafacc7d2 100644 (file)
--- a/drivers/tty/vt/selection.c
+++ b/drivers/tty/vt/selection.c
@@ -158,7 +158,7 @@ static int store_utf8(u16 c, char *p)
  *     The entire selection process is managed under the console_lock. It's
  *      a lot under the lock but its hardly a performance path
  */
-int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *tty)
+static int __set_selection(const struct tiocl_selection __user *sel, struct tty_struct *tty)
 {
        struct vc_data *vc = vc_cons[fg_console].d;
        int sel_mode, new_sel_start, new_sel_end, spc;
@@ -334,6 +334,17 @@ int set_selection(const struct tiocl_selection __user *sel, struct tty_struct *t
        return ret;
 }
 
+int set_selection(const struct tiocl_selection __user *v, struct tty_struct *tty)
+{
+       int ret;
+
+       console_lock();
+       ret = __set_selection(v, tty);
+       console_unlock();
+
+       return ret;
+}
+
 /* Insert the contents of the selection buffer into the
  * queue of the tty associated with the current console.
  * Invoked by ioctl().

diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index 6f5d249d454d195ee31895020e648ccdbf9dea65..b9d4075ddc176ef79235940a0aa8217d3c57bd13 100644 (file)
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -2670,9 +2670,7 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
        switch (type)
        {
                case TIOCL_SETSEL:
-                       console_lock();
                        ret = set_selection((struct tiocl_selection __user *)(p+1), tty);
-                       console_unlock();
                        break;
                case TIOCL_PASTESEL:
                        ret = paste_selection(tty);