From: Robin Murphy Date: Thu, 24 Nov 2016 14:40:50 +0000 (+0000) Subject: drm: hdlcd: Fix cleanup order X-Git-Tag: v4.9-rc8~1^2~2^2 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=747e5a5ff2a2ae84715c33d6679ac3c5220a3aec;p=linux.git drm: hdlcd: Fix cleanup order If hdlcd_drm_bind() fails at drm_fbdev_cma_init(), its cleanup will call drm_mode_config_cleanup() as if to balance drm_mode_config_reset(). The net result is that drm_connector_cleanup() will clean up the active connectors long before component_unbind_all() gets called, so when the connector later tries to clean up itself after being unbound, Bad Things can happen: [ 4.121888] Unable to handle kernel NULL pointer dereference at virtual address 00000000 [ 4.129951] pgd = ffffff80091e0000 [ 4.133345] [00000000] *pgd=00000009ffffe003, *pud=00000009ffffe003, *pmd=0000000000000000 [ 4.141613] Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 4.147144] Modules linked in: [ 4.150188] CPU: 0 PID: 122 Comm: kworker/u12:2 Not tainted 4.8.0-rc2+ #989 [ 4.157097] Hardware name: ARM Juno development board (r1) (DT) [ 4.162981] Workqueue: deferwq deferred_probe_work_func [ 4.168173] task: ffffffc975d93200 task.stack: ffffffc975dac000 [ 4.174055] PC is at drm_connector_cleanup+0x58/0x1c0 [ 4.179074] LR is at tda998x_unbind+0x24/0x40 [ 4.183401] pc : [] lr : [] pstate: 00000045 [ 4.190750] sp : ffffffc975dafa10 [ 4.194041] x29: ffffffc975dafa10 x28: ffffffc9768152a8 [ 4.199325] x27: ffffffc97ff46450 x26: ffffff8008d99000 [ 4.204608] x25: dead000000000100 x24: dead000000000200 [ 4.209891] x23: ffffffc976bf91e8 x22: 0000000000000000 [ 4.215172] x21: ffffffc976bf9170 x20: ffffffc976bf9170 [ 4.220454] x19: ffffffc976bf9018 x18: 0000000000000000 [ 4.225737] x17: 0000000074ce71ee x16: 000000008ff5d35f [ 4.231019] x15: ffffffc97681e91c x14: ffffffffffffffff [ 4.236301] x13: ffffffc97681e185 x12: 0000000000000038 [ 4.241583] x11: 0101010101010101 x10: 0000000000000000 [ 4.246866] x9 : 0000000040000000 x8 : 0000000000210d00 [ 4.252148] x7 : ffffffc97fea8c00 x6 : 000000000000001b [ 4.257430] x5 : ffffff80084b7b8c x4 : 0000000000000080 [ 4.262712] x3 : ffffff8008504128 x2 : ffffffc975df3800 [ 4.267993] x1 : 0000000000000000 x0 : 0000000000000000 ... [ 4.750937] [] drm_connector_cleanup+0x58/0x1c0 [ 4.756990] [] tda998x_unbind+0x24/0x40 [ 4.762354] [] component_unbind.isra.4+0x28/0x50 [ 4.768492] [] component_unbind_all+0xcc/0xd8 [ 4.774373] [] hdlcd_drm_bind+0x234/0x418 [ 4.779909] [] try_to_bring_up_master+0x140/0x1a0 [ 4.786133] [] component_add+0x98/0x170 [ 4.791496] [] tda998x_probe+0x18/0x20 [ 4.796774] [] i2c_device_probe+0x164/0x258 [ 4.802481] [] driver_probe_device+0x204/0x2b0 [ 4.808447] [] __device_attach_driver+0x9c/0xf8 [ 4.814498] [] bus_for_each_drv+0x58/0x98 [ 4.820033] [] __device_attach+0xc4/0x138 [ 4.825567] [] device_initial_probe+0x10/0x18 [ 4.831446] [] bus_probe_device+0x94/0xa0 [ 4.836981] [] deferred_probe_work_func+0x78/0xb0 [ 4.843207] [] process_one_work+0x118/0x378 [ 4.848914] [] worker_thread+0x48/0x498 [ 4.854276] [] kthread+0xd0/0xe8 [ 4.859036] [] ret_from_fork+0x10/0x40 [ 4.864314] Code: f2fbd5b9 f2fbd5b8 f8478ee0 eb17001f (f9400013) [ 4.870472] ---[ end trace a643cfe4ce1d838b ]--- Fix this by moving the drm_mode_config_cleanup() much later such that it correctly balances drm_mode_config_init(). Suggested-by: Russell King Signed-off-by: Robin Murphy Signed-off-by: Liviu Dudau --- diff --git a/drivers/gpu/drm/arm/hdlcd_drv.c b/drivers/gpu/drm/arm/hdlcd_drv.c index fb6a418ce6be..e138fb51e8ce 100644 --- a/drivers/gpu/drm/arm/hdlcd_drv.c +++ b/drivers/gpu/drm/arm/hdlcd_drv.c @@ -375,7 +375,6 @@ static int hdlcd_drm_bind(struct device *dev) err_fbdev: drm_kms_helper_poll_fini(drm); - drm_mode_config_cleanup(drm); drm_vblank_cleanup(drm); err_vblank: pm_runtime_disable(drm->dev); @@ -387,6 +386,7 @@ static int hdlcd_drm_bind(struct device *dev) drm_irq_uninstall(drm); of_reserved_mem_device_release(drm->dev); err_free: + drm_mode_config_cleanup(drm); dev_set_drvdata(dev, NULL); drm_dev_unref(drm);