Commit 66c1ca01 authored by Andrea Righi's avatar Andrea Righi Committed by Linus Torvalds
Browse files

fbmem: fix fb_info->lock and mm->mmap_sem circular locking dependency 



Fix a circular locking dependency in the frame buffer console driver
pushing down the mutex fb_info->lock.

Circular locking dependecies occur calling the blocking
fb_notifier_call_chain() with fb_info->lock held.  Notifier callbacks can
try to acquire mm->mmap_sem, while fb_mmap() acquires the locks in the
reverse order mm->mmap_sem => fb_info->lock.

Tested-by: default avatarAndrey Borzenkov <arvidjaar@mail.ru>
Signed-off-by: default avatarAndrea Righi <righi.andrea@gmail.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: <stable@kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8636a924

drivers/video/backlight/backlight.c

+3 −0
Original line number Diff line number Diff line
@@ -35,6 +35,8 @@ static int fb_notifier_callback(struct notifier_block *self, 
		return 0;



	bd = container_of(self, struct backlight_device, fb_notif);

	if (!lock_fb_info(evdata->info))

		return -ENODEV;

	mutex_lock(&bd->ops_lock);

	if (bd->ops)

		if (!bd->ops->check_fb ||
@@ -47,6 +49,7 @@ static int fb_notifier_callback(struct notifier_block *self, 
			backlight_update_status(bd);

		}

	mutex_unlock(&bd->ops_lock);

	unlock_fb_info(evdata->info);

	return 0;

}

drivers/video/backlight/lcd.c

+3 −0
Original line number Diff line number Diff line
@@ -40,6 +40,8 @@ static int fb_notifier_callback(struct notifier_block *self, 
	if (!ld->ops)

		return 0;



	if (!lock_fb_info(evdata->info))

		return -ENODEV;

	mutex_lock(&ld->ops_lock);

	if (!ld->ops->check_fb || ld->ops->check_fb(ld, evdata->info)) {

		if (event == FB_EVENT_BLANK) {
@@ -51,6 +53,7 @@ static int fb_notifier_callback(struct notifier_block *self, 
		}

	}

	mutex_unlock(&ld->ops_lock);

	unlock_fb_info(evdata->info);

	return 0;

}

drivers/video/console/fbcon.c

+63 −10
Original line number Diff line number Diff line
@@ -2954,8 +2954,11 @@ static int fbcon_fb_unbind(int idx) 


static int fbcon_fb_unregistered(struct fb_info *info)

{

	int i, idx = info->node;

	int i, idx;



	if (!lock_fb_info(info))

		return -ENODEV;

	idx = info->node;

	for (i = first_fb_vc; i <= last_fb_vc; i++) {

		if (con2fb_map[i] == idx)

			con2fb_map[i] = -1;
@@ -2979,13 +2982,14 @@ static int fbcon_fb_unregistered(struct fb_info *info) 
		}

	}



	if (!num_registered_fb)

		unregister_con_driver(&fb_con);





	if (primary_device == idx)

		primary_device = -1;



	unlock_fb_info(info);



	if (!num_registered_fb)

		unregister_con_driver(&fb_con);



	return 0;

}
@@ -3021,9 +3025,13 @@ static inline void fbcon_select_primary(struct fb_info *info) 


static int fbcon_fb_registered(struct fb_info *info)

{

	int ret = 0, i, idx = info->node;

	int ret = 0, i, idx;



	if (!lock_fb_info(info))

		return -ENODEV;

	idx = info->node;

	fbcon_select_primary(info);

	unlock_fb_info(info);



	if (info_idx == -1) {

		for (i = first_fb_vc; i <= last_fb_vc; i++) {
@@ -3132,7 +3140,7 @@ static int fbcon_event_notify(struct notifier_block *self, 
	struct fb_videomode *mode;

	struct fb_con2fbmap *con2fb;

	struct fb_blit_caps *caps;

	int ret = 0;

	int idx, ret = 0;



	/*

	 * ignore all events except driver registration and deregistration
@@ -3144,23 +3152,54 @@ static int fbcon_event_notify(struct notifier_block *self, 


	switch(action) {

	case FB_EVENT_SUSPEND:

		if (!lock_fb_info(info)) {

			ret = -ENODEV;

			goto done;

		}

		fbcon_suspended(info);

		unlock_fb_info(info);

		break;

	case FB_EVENT_RESUME:

		if (!lock_fb_info(info)) {

			ret = -ENODEV;

			goto done;

		}

		fbcon_resumed(info);

		unlock_fb_info(info);

		break;

	case FB_EVENT_MODE_CHANGE:

		if (!lock_fb_info(info)) {

			ret = -ENODEV;

			goto done;

		}

		fbcon_modechanged(info);

		unlock_fb_info(info);

		break;

	case FB_EVENT_MODE_CHANGE_ALL:

		if (!lock_fb_info(info)) {

			ret = -ENODEV;

			goto done;

		}

		fbcon_set_all_vcs(info);

		unlock_fb_info(info);

		break;

	case FB_EVENT_MODE_DELETE:

		mode = event->data;

		if (!lock_fb_info(info)) {

			ret = -ENODEV;

			goto done;

		}

		ret = fbcon_mode_deleted(info, mode);

		unlock_fb_info(info);

		break;

	case FB_EVENT_FB_UNBIND:

		ret = fbcon_fb_unbind(info->node);

		if (!lock_fb_info(info)) {

			ret = -ENODEV;

			goto done;

		}

		idx = info->node;

		unlock_fb_info(info);

		ret = fbcon_fb_unbind(idx);

		break;

	case FB_EVENT_FB_REGISTERED:

		ret = fbcon_fb_registered(info);
@@ -3178,17 +3217,31 @@ static int fbcon_event_notify(struct notifier_block *self, 
		con2fb->framebuffer = con2fb_map[con2fb->console - 1];

		break;

	case FB_EVENT_BLANK:

		if (!lock_fb_info(info)) {

			ret = -ENODEV;

			goto done;

		}

		fbcon_fb_blanked(info, *(int *)event->data);

		unlock_fb_info(info);

		break;

	case FB_EVENT_NEW_MODELIST:

		if (!lock_fb_info(info)) {

			ret = -ENODEV;

			goto done;

		}

		fbcon_new_modelist(info);

		unlock_fb_info(info);

		break;

	case FB_EVENT_GET_REQ:

		caps = event->data;

		if (!lock_fb_info(info)) {

			ret = -ENODEV;

			goto done;

		}

		fbcon_get_requirement(info, caps);

		unlock_fb_info(info);

		break;

	}



done:

	return ret;

}

drivers/video/fbmem.c

+1 −10
Original line number Diff line number Diff line
@@ -1086,13 +1086,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, 
			return -EINVAL;

		con2fb.framebuffer = -1;

		event.data = &con2fb;



		if (!lock_fb_info(info))

			return -ENODEV;

		event.info = info;

		fb_notifier_call_chain(FB_EVENT_GET_CONSOLE_MAP, &event);

		unlock_fb_info(info);



		ret = copy_to_user(argp, &con2fb, sizeof(con2fb)) ? -EFAULT : 0;

		break;

	case FBIOPUT_CON2FBMAP:
@@ -1109,12 +1104,8 @@ static long do_fb_ioctl(struct fb_info *info, unsigned int cmd, 
			break;

		}

		event.data = &con2fb;

		if (!lock_fb_info(info))

			return -ENODEV;

		event.info = info;

		ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP,

					      &event);

		unlock_fb_info(info);

		ret = fb_notifier_call_chain(FB_EVENT_SET_CONSOLE_MAP, &event);

		break;

	case FBIOBLANK:

		if (!lock_fb_info(info))

CRA Git | Maintained and supported by SUSTech CRA and CCSE