From 66c1ca019078220dc1bf968f2bb18421100ef147 Mon Sep 17 00:00:00 2001 From: Andrea Righi Date: Tue, 31 Mar 2009 15:25:18 -0700 Subject: 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: Andrey Borzenkov Signed-off-by: Andrea Righi Cc: Geert Uytterhoeven Cc: Krzysztof Helt Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/video/console/fbcon.c | 73 +++++++++++++++++++++++++++++++++++++------ 1 file changed, 63 insertions(+), 10 deletions(-) (limited to 'drivers/video/console/fbcon.c') diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c index 1657b9608b0..2cd500a304f 100644 --- a/drivers/video/console/fbcon.c +++ b/drivers/video/console/fbcon.c @@ -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++) { @@ -3124,7 +3132,7 @@ static void fbcon_get_requirement(struct fb_info *info, } } -static int fbcon_event_notify(struct notifier_block *self, +static int fbcon_event_notify(struct notifier_block *self, unsigned long action, void *data) { struct fb_event *event = data; @@ -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; } -- cgit From 513adb58685615b0b1d47a3f0d40f5352beff189 Mon Sep 17 00:00:00 2001 From: Andrea Righi Date: Mon, 13 Apr 2009 14:39:39 -0700 Subject: fbdev: fix info->lock deadlock in fbcon_event_notify() 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. Reported-by: Pavel Roskin Reported-by: Eric Miao Signed-off-by: Andrea Righi Cc: Stefan Richter Cc: Krzysztof Helt Cc: Geert Uytterhoeven Cc: "Rafael J. Wysocki" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/video/console/fbcon.c | 55 +++---------------------------------------- 1 file changed, 3 insertions(+), 52 deletions(-) (limited to 'drivers/video/console/fbcon.c') diff --git a/drivers/video/console/fbcon.c b/drivers/video/console/fbcon.c index 2cd500a304f..471a9a60376 100644 --- 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: -- cgit