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authorNoralf Trønnes <noralf@tronnes.org>2018-10-01 22:45:36 +0300
committerNoralf Trønnes <noralf@tronnes.org>2018-10-02 14:03:34 +0300
commit4d4c2d89913e2d891bd6a34b12050a2576e60525 (patch)
tree5b1ead135c30e41f26979ebc70d02d55af8b7774 /drivers/gpu
parent12d43deb1ee639d01a2a8d2a7a4cc8ad31224475 (diff)
downloadlinux-4d4c2d89913e2d891bd6a34b12050a2576e60525.tar.xz
drm/cma-helper: Fix crash in fbdev error path
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 <ssuloev@orpaltech.com> Cc: Stefan Wahren <stefan.wahren@i2se.com> Cc: Eric Anholt <eric@anholt.net> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by: Noralf Trønnes <noralf@tronnes.org> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20181001194536.57756-1-noralf@tronnes.org
Diffstat (limited to 'drivers/gpu')
-rw-r--r--drivers/gpu/drm/drm_client.c35
-rw-r--r--drivers/gpu/drm/drm_fb_cma_helper.c4
-rw-r--r--drivers/gpu/drm/drm_fb_helper.c4
3 files changed, 32 insertions, 11 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 @@ err_put_module:
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);