fbdev: fix info->lock deadlock in fbcon_event_notify()

upstream commit: 513adb58685615b0b1d47a3f0d40f5352beff189

fb_notifier_call_chain() is called with info->lock held, i.e.  in
do_fb_ioctl() => FBIOPUT_VSCREENINFO => fb_set_var() and the some
notifier callbacks, like fbcon_event_notify(), try to re-acquire
info->lock again.

Remove the lock/unlock_fb_info() in all the framebuffer notifier
callbacks' and be sure to always call fb_notifier_call_chain() with
info->lock held.

[fixes hang caused by 66c1ca01]

Reported-by: Pavel Roskin <proski@gnu.org>
Reported-by: Eric Miao <eric.y.miao@gmail.com>
Signed-off-by: Andrea Righi <righi.andrea@gmail.com>
Cc: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index dd37cbcaf8ce164a4ac5e7293a745204ede08ac4..157057c79ca3760fc80d6df28236dc0bbf106044 100644 (file)
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -35,8 +35,6 @@ 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 ||
@@ -49,7 +47,6 @@ 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;
 }
 

diff --git a/drivers/video/backlight/lcd.c b/drivers/video/backlight/lcd.c
index 0bb13df0fa89e2b3ca01c9468a47cadd2f5a8b88..b6449470106cd47e8db704edfd074c53dde8ec4b 100644 (file)
--- a/drivers/video/backlight/lcd.c
+++ b/drivers/video/backlight/lcd.c
@@ -40,8 +40,6 @@ 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) {
@@ -53,7 +51,6 @@ static int fb_notifier_callback(struct notifier_block *self,
                }
        }
        mutex_unlock(&ld->ops_lock);
-       unlock_fb_info(evdata->info);
        return 0;
 }
 

diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c
index 2cd500a304f234456c083baf920255a657c650f9..471a9a60376ae82a07a921e416b0ec35fb4dbdfe 100644 (file)
--- a/drivers/video/console/fbcon.c
+++ b/drivers/video/console/fbcon.c
@@ -2263,9 +2263,12 @@ static void fbcon_generic_blank(struct vc_data *vc, struct fb_info *info,
        }
 
 
+       if (!lock_fb_info(info))
+               return;
        event.info = info;
        event.data = ␣
        fb_notifier_call_chain(FB_EVENT_CONBLANK, &event);
+       unlock_fb_info(info);
 }
 
 static int fbcon_blank(struct vc_data *vc, int blank, int mode_switch)
@@ -2956,8 +2959,6 @@ static int fbcon_fb_unregistered(struct fb_info *info)
 {
        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)
@@ -2985,8 +2986,6 @@ static int fbcon_fb_unregistered(struct fb_info *info)
        if (primary_device == idx)
                primary_device = -1;
 
-       unlock_fb_info(info);
-
        if (!num_registered_fb)
                unregister_con_driver(&fb_con);
 
@@ -3027,11 +3026,8 @@ static int fbcon_fb_registered(struct fb_info *info)
 {
        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++) {
@@ -3152,53 +3148,23 @@ 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:
-               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:
@@ -3217,29 +3183,14 @@ 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:

diff --git a/drivers/video/fbmem.c b/drivers/video/fbmem.c
index b64f061dd447222f6202ca715ed8d87bef483e1c..1d6fb419379994c71ee8a980272e8b3d58943436 100644 (file)
--- a/drivers/video/fbmem.c
+++ b/drivers/video/fbmem.c
@@ -1086,8 +1086,11 @@ 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:
@@ -1104,8 +1107,11 @@ 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);
                break;
        case FBIOBLANK:
                if (!lock_fb_info(info))
@@ -1510,7 +1516,10 @@ register_framebuffer(struct fb_info *fb_info)
        registered_fb[i] = fb_info;
 
        event.info = fb_info;
+       if (!lock_fb_info(fb_info))
+               return -ENODEV;
        fb_notifier_call_chain(FB_EVENT_FB_REGISTERED, &event);
+       unlock_fb_info(fb_info);
        return 0;
 }
 
@@ -1544,8 +1553,12 @@ unregister_framebuffer(struct fb_info *fb_info)
                goto done;
        }
 
+
+       if (!lock_fb_info(fb_info))
+               return -ENODEV;
        event.info = fb_info;
        ret = fb_notifier_call_chain(FB_EVENT_FB_UNBIND, &event);
+       unlock_fb_info(fb_info);
 
        if (ret) {
                ret = -EINVAL;
@@ -1579,6 +1592,8 @@ void fb_set_suspend(struct fb_info *info, int state)
 {
        struct fb_event event;
 
+       if (!lock_fb_info(info))
+               return;
        event.info = info;
        if (state) {
                fb_notifier_call_chain(FB_EVENT_SUSPEND, &event);
@@ -1587,6 +1602,7 @@ void fb_set_suspend(struct fb_info *info, int state)
                info->state = FBINFO_STATE_RUNNING;
                fb_notifier_call_chain(FB_EVENT_RESUME, &event);
        }
+       unlock_fb_info(info);
 }
 
 /**
@@ -1656,8 +1672,11 @@ int fb_new_modelist(struct fb_info *info)
        err = 1;
 
        if (!list_empty(&info->modelist)) {
+               if (!lock_fb_info(info))
+                       return -ENODEV;
                event.info = info;
                err = fb_notifier_call_chain(FB_EVENT_NEW_MODELIST, &event);
+               unlock_fb_info(info);
        }
 
        return err;