vt_ioctl: fix GIO_UNIMAP regression

In commit 5ba127878722, we shuffled with the check of 'perm'. But my
brain somehow inverted the condition in 'do_unimap_ioctl' (I thought
it is ||, not &&), so GIO_UNIMAP stopped working completely.

Move the 'perm' checks back to do_unimap_ioctl and do them right again.
In fact, this reverts this part of code to the pre-5ba127878722 state.
Except 'perm' is now a bool.

Fixes: 5ba127878722 ("vt_ioctl: move perm checks level up")
Cc: stable@vger.kernel.org
Reported-by: Fabian Vogt <fvogt@suse.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Link: https://lore.kernel.org/r/20201026055419.30518-1-jslaby@suse.cz
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index 0a33b8a..2321775 100644 (file)
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -549,7 +549,7 @@ static int vt_io_fontreset(struct console_font_op *op)
 }
 
 static inline int do_unimap_ioctl(int cmd, struct unimapdesc __user *user_ud,
-               struct vc_data *vc)
+               bool perm, struct vc_data *vc)
 {
        struct unimapdesc tmp;
 
@@ -557,9 +557,11 @@ static inline int do_unimap_ioctl(int cmd, struct unimapdesc __user *user_ud,
                return -EFAULT;
        switch (cmd) {
        case PIO_UNIMAP:
+               if (!perm)
+                       return -EPERM;
                return con_set_unimap(vc, tmp.entry_ct, tmp.entries);
        case GIO_UNIMAP:
-               if (fg_console != vc->vc_num)
+               if (!perm && fg_console != vc->vc_num)
                        return -EPERM;
                return con_get_unimap(vc, tmp.entry_ct, &(user_ud->entry_ct),
                                tmp.entries);
@@ -639,10 +641,7 @@ static int vt_io_ioctl(struct vc_data *vc, unsigned int cmd, void __user *up,
 
        case PIO_UNIMAP:
        case GIO_UNIMAP:
-               if (!perm)
-                       return -EPERM;
-
-               return do_unimap_ioctl(cmd, up, vc);
+               return do_unimap_ioctl(cmd, up, perm, vc);
 
        default:
                return -ENOIOCTLCMD;