From 4d4c2d89913e2d891bd6a34b12050a2576e60525 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= Date: Mon, 1 Oct 2018 21:45:36 +0200 Subject: [PATCH] drm/cma-helper: Fix crash in fbdev error path MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sergey Suloev reported a crash happening in drm_client_dev_hotplug() when fbdev had failed to register. [ 9.124598] vc4_hdmi 3f902000.hdmi: ASoC: Failed to create component debugfs directory [ 9.147667] vc4_hdmi 3f902000.hdmi: vc4-hdmi-hifi <-> 3f902000.hdmi mapping ok [ 9.155184] vc4_hdmi 3f902000.hdmi: ASoC: no DMI vendor name! [ 9.166544] vc4-drm soc:gpu: bound 3f902000.hdmi (ops vc4_hdmi_ops [vc4]) [ 9.173840] vc4-drm soc:gpu: bound 3f806000.vec (ops vc4_vec_ops [vc4]) [ 9.181029] vc4-drm soc:gpu: bound 3f004000.txp (ops vc4_txp_ops [vc4]) [ 9.188519] vc4-drm soc:gpu: bound 3f400000.hvs (ops vc4_hvs_ops [vc4]) [ 9.195690] vc4-drm soc:gpu: bound 3f206000.pixelvalve (ops vc4_crtc_ops [vc4]) [ 9.203523] vc4-drm soc:gpu: bound 3f207000.pixelvalve (ops vc4_crtc_ops [vc4]) [ 9.215032] vc4-drm soc:gpu: bound 3f807000.pixelvalve (ops vc4_crtc_ops [vc4]) [ 9.274785] vc4-drm soc:gpu: bound 3fc00000.v3d (ops vc4_v3d_ops [vc4]) [ 9.290246] [drm] Initialized vc4 0.0.0 20140616 for soc:gpu on minor 0 [ 9.297464] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013). [ 9.304600] [drm] Driver supports precise vblank timestamp query. [ 9.382856] vc4-drm soc:gpu: [drm:drm_fb_helper_fbdev_setup [drm_kms_helper]] *ERROR* Failed to set fbdev configuration [ 10.404937] Unable to handle kernel paging request at virtual address 00330a656369768a [ 10.441620] [00330a656369768a] address between user and kernel address ranges [ 10.449087] Internal error: Oops: 96000004 [#1] PREEMPT SMP [ 10.454762] Modules linked in: brcmfmac vc4 drm_kms_helper cfg80211 drm rfkill smsc95xx brcmutil usbnet drm_panel_orientation_quirks raspberrypi_hwmon bcm2835_dma crc32_ce pwm_bcm2835 bcm2835_rng virt_dma rng_core i2c_bcm2835 ip_tables x_tables ipv6 [ 10.477296] CPU: 2 PID: 45 Comm: kworker/2:1 Not tainted 4.19.0-rc5 #3 [ 10.483934] Hardware name: Raspberry Pi 3 Model B Rev 1.2 (DT) [ 10.489966] Workqueue: events output_poll_execute [drm_kms_helper] [ 10.596515] Process kworker/2:1 (pid: 45, stack limit = 0x000000007e8924dc) [ 10.603590] Call trace: [ 10.606259] drm_client_dev_hotplug+0x5c/0xb0 [drm] [ 10.611303] drm_kms_helper_hotplug_event+0x30/0x40 [drm_kms_helper] [ 10.617849] output_poll_execute+0xc4/0x1e0 [drm_kms_helper] [ 10.623616] process_one_work+0x1c8/0x318 [ 10.627695] worker_thread+0x48/0x428 [ 10.631420] kthread+0xf8/0x128 [ 10.634615] ret_from_fork+0x10/0x18 [ 10.638255] Code: 54000220 f9401261 aa1303e0 b4000141 (f9400c21) [ 10.644456] ---[ end trace c75b4a4b0e141908 ]--- The reason for this is that drm_fbdev_cma_init() removes the drm_client when fbdev registration fails, but it doesn't remove the client from the drm_device client list. So the client list now has a pointer that points into the unknown and we have a 'use after free' situation. Split drm_client_new() into drm_client_init() and drm_client_add() to fix removal in the error path. Fixes: 894a677f4b3e ("drm/cma-helper: Use the generic fbdev emulation") Reported-by: Sergey Suloev Cc: Stefan Wahren Cc: Eric Anholt Cc: Daniel Vetter Signed-off-by: Noralf Trønnes Reviewed-by: Daniel Vetter Link: https://patchwork.freedesktop.org/patch/msgid/20181001194536.57756-1-noralf@tronnes.org --- drivers/gpu/drm/drm_client.c | 35 +++++++++++++++++++++-------- drivers/gpu/drm/drm_fb_cma_helper.c | 4 +++- drivers/gpu/drm/drm_fb_helper.c | 4 +++- include/drm/drm_client.h | 5 +++-- 4 files changed, 35 insertions(+), 13 deletions(-) diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c index baff50a4c234..df31c3815092 100644 --- a/drivers/gpu/drm/drm_client.c +++ b/drivers/gpu/drm/drm_client.c @@ -63,20 +63,21 @@ static void drm_client_close(struct drm_client_dev *client) EXPORT_SYMBOL(drm_client_close); /** - * drm_client_new - Create a DRM client + * drm_client_init - Initialise a DRM client * @dev: DRM device * @client: DRM client * @name: Client name * @funcs: DRM client functions (optional) * + * This initialises the client and opens a &drm_file. Use drm_client_add() to complete the process. * The caller needs to hold a reference on @dev before calling this function. * The client is freed when the &drm_device is unregistered. See drm_client_release(). * * Returns: * Zero on success or negative error code on failure. */ -int drm_client_new(struct drm_device *dev, struct drm_client_dev *client, - const char *name, const struct drm_client_funcs *funcs) +int drm_client_init(struct drm_device *dev, struct drm_client_dev *client, + const char *name, const struct drm_client_funcs *funcs) { int ret; @@ -95,10 +96,6 @@ int drm_client_new(struct drm_device *dev, struct drm_client_dev *client, if (ret) goto err_put_module; - mutex_lock(&dev->clientlist_mutex); - list_add(&client->list, &dev->clientlist); - mutex_unlock(&dev->clientlist_mutex); - drm_dev_get(dev); return 0; @@ -109,13 +106,33 @@ int drm_client_new(struct drm_device *dev, struct drm_client_dev *client, return ret; } -EXPORT_SYMBOL(drm_client_new); +EXPORT_SYMBOL(drm_client_init); + +/** + * drm_client_add - Add client to the device list + * @client: DRM client + * + * Add the client to the &drm_device client list to activate its callbacks. + * @client must be initialized by a call to drm_client_init(). After + * drm_client_add() it is no longer permissible to call drm_client_release() + * directly (outside the unregister callback), instead cleanup will happen + * automatically on driver unload. + */ +void drm_client_add(struct drm_client_dev *client) +{ + struct drm_device *dev = client->dev; + + mutex_lock(&dev->clientlist_mutex); + list_add(&client->list, &dev->clientlist); + mutex_unlock(&dev->clientlist_mutex); +} +EXPORT_SYMBOL(drm_client_add); /** * drm_client_release - Release DRM client resources * @client: DRM client * - * Releases resources by closing the &drm_file that was opened by drm_client_new(). + * Releases resources by closing the &drm_file that was opened by drm_client_init(). * It is called automatically if the &drm_client_funcs.unregister callback is _not_ set. * * This function should only be called from the unregister callback. An exception diff --git a/drivers/gpu/drm/drm_fb_cma_helper.c b/drivers/gpu/drm/drm_fb_cma_helper.c index 9da36a6271d3..9ac1f2e0f064 100644 --- a/drivers/gpu/drm/drm_fb_cma_helper.c +++ b/drivers/gpu/drm/drm_fb_cma_helper.c @@ -160,7 +160,7 @@ struct drm_fbdev_cma *drm_fbdev_cma_init(struct drm_device *dev, fb_helper = &fbdev_cma->fb_helper; - ret = drm_client_new(dev, &fb_helper->client, "fbdev", NULL); + ret = drm_client_init(dev, &fb_helper->client, "fbdev", NULL); if (ret) goto err_free; @@ -169,6 +169,8 @@ struct drm_fbdev_cma *drm_fbdev_cma_init(struct drm_device *dev, if (ret) goto err_client_put; + drm_client_add(&fb_helper->client); + return fbdev_cma; err_client_put: diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c index 16ec93b75dbf..515a7aec57ac 100644 --- a/drivers/gpu/drm/drm_fb_helper.c +++ b/drivers/gpu/drm/drm_fb_helper.c @@ -3218,12 +3218,14 @@ int drm_fbdev_generic_setup(struct drm_device *dev, unsigned int preferred_bpp) if (!fb_helper) return -ENOMEM; - ret = drm_client_new(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs); + ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_client_funcs); if (ret) { kfree(fb_helper); return ret; } + drm_client_add(&fb_helper->client); + fb_helper->preferred_bpp = preferred_bpp; drm_fbdev_client_hotplug(&fb_helper->client); diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h index 989f8e52864d..971bb7853776 100644 --- a/include/drm/drm_client.h +++ b/include/drm/drm_client.h @@ -87,9 +87,10 @@ struct drm_client_dev { struct drm_file *file; }; -int drm_client_new(struct drm_device *dev, struct drm_client_dev *client, - const char *name, const struct drm_client_funcs *funcs); +int drm_client_init(struct drm_device *dev, struct drm_client_dev *client, + const char *name, const struct drm_client_funcs *funcs); void drm_client_release(struct drm_client_dev *client); +void drm_client_add(struct drm_client_dev *client); void drm_client_dev_unregister(struct drm_device *dev); void drm_client_dev_hotplug(struct drm_device *dev);