tty: vt: pass proper pointers from tioclinux()

BugLink: https://bugs.launchpad.net/bugs/2114239

Pass proper types and proper pointers (the data with an offset) to the
TIOCL_* handlers. So that they need not to cast or add anything to the
passed pointer.

This makes obvious what is passed/consumed.

Signed-off-by: "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Tested-by: Helge Deller <deller@gmx.de> # parisc STI console
Link: https://lore.kernel.org/r/20240122110401.7289-6-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit a0b8a1681254346010edd2f94e799fb6b6568cf1)
[nwager: This is just a cleanup commit that doesn't change behaviour and
makes the following 6.12.14 patch apply cleanly:
e46d91ca504d ("tty: Permit some TIOCL_SETSEL modes without CAP_SYS_ADMIN")]
Signed-off-by: Noah Wager <noah.wager@canonical.com>
Signed-off-by: Mehmet Basaran <mehmet.basaran@canonical.com>

drivers/tty/vt/selection.c

@@ -7,7 +7,7 @@
  *     'int set_selection_kernel(struct tiocl_selection *, struct tty_struct *)'
  *     'void clear_selection(void)'
  *     'int paste_selection(struct tty_struct *)'
- *     'int sel_loadlut(char __user *)'
+ *     'int sel_loadlut(u32 __user *)'
  *
  * Now that /dev/vcs exists, most of this can disappear again.
  */
@@ -111,15 +111,15 @@ static inline int inword(const u32 c)
 
 /**
  *	sel_loadlut()		-	load the LUT table
- *	@p: user table
+ *	@lut: user table
  *
  *	Load the LUT table from user space. The caller must hold the console
  *	lock. Make a temporary copy so a partial update doesn't make a mess.
  */
-int sel_loadlut(char __user *p)
+int sel_loadlut(u32 __user *lut)
 {
 	u32 tmplut[ARRAY_SIZE(inwordLut)];
-	if (copy_from_user(tmplut, (u32 __user *)(p+4), sizeof(inwordLut)))
+	if (copy_from_user(tmplut, lut, sizeof(inwordLut)))
 		return -EFAULT;
 	memcpy(inwordLut, tmplut, sizeof(inwordLut));
 	return 0;

drivers/tty/vt/vt.c

@@ -145,7 +145,7 @@ static void gotoxy(struct vc_data *vc, int new_x, int new_y);
 static void save_cur(struct vc_data *vc);
 static void reset_terminal(struct vc_data *vc, int do_clear);
 static void con_flush_chars(struct tty_struct *tty);
-static int set_vesa_blanking(char __user *p);
+static int set_vesa_blanking(u8 __user *mode);
 static void set_cursor(struct vc_data *vc);
 static void hide_cursor(struct vc_data *vc);
 static void console_callback(struct work_struct *ignored);
@@ -3144,6 +3144,8 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
 {
 	char type, data;
 	char __user *p = (char __user *)arg;
+	void __user *param_aligned32 = (u32 __user *)arg + 1;
+	void __user *param = (void __user *)arg + 1;
 	int lines;
 	int ret;
 
@@ -3157,8 +3159,7 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
 	case TIOCL_SETSEL:
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
-		return set_selection_user((struct tiocl_selection
-					 __user *)(p+1), tty);
+		return set_selection_user(param, tty);
 	case TIOCL_PASTESEL:
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
@@ -3172,7 +3173,7 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
 		if (!capable(CAP_SYS_ADMIN))
 			return -EPERM;
 		console_lock();
-		ret = sel_loadlut(p);
+		ret = sel_loadlut(param_aligned32);
 		console_unlock();
 		break;
 	case TIOCL_GETSHIFTSTATE:
@@ -3191,7 +3192,7 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
 		return put_user(data, p);
 	case TIOCL_SETVESABLANK:
 		console_lock();
-		ret = set_vesa_blanking(p);
+		ret = set_vesa_blanking(param);
 		console_unlock();
 		break;
 	case TIOCL_GETKMSGREDIRECT:
@@ -3214,7 +3215,7 @@ int tioclinux(struct tty_struct *tty, unsigned long arg)
 		 */
 		return fg_console;
 	case TIOCL_SCROLLCONSOLE:
-		if (get_user(lines, (s32 __user *)(p+4)))
+		if (get_user(lines, (s32 __user *)param_aligned32))
 			return -EFAULT;
 
 		/*
@@ -4285,11 +4286,11 @@ postcore_initcall(vtconsole_class_init);
  *	Screen blanking
  */
 
-static int set_vesa_blanking(char __user *p)
+static int set_vesa_blanking(u8 __user *mode_user)
 {
-	unsigned int mode;
+	u8 mode;
 
-	if (get_user(mode, p + 1))
+	if (get_user(mode, mode_user))
 		return -EFAULT;
 
 	vesa_blank_mode = (mode < 4) ? mode : 0;

include/linux/selection.h

@@ -20,7 +20,7 @@ extern int set_selection_user(const struct tiocl_selection __user *sel,
 extern int set_selection_kernel(struct tiocl_selection *v,
 				struct tty_struct *tty);
 extern int paste_selection(struct tty_struct *tty);
-extern int sel_loadlut(char __user *p);
+extern int sel_loadlut(u32 __user *lut);
 extern int mouse_reporting(void);
 extern void mouse_report(struct tty_struct * tty, int butt, int mrx, int mry);