From: Ville Syrjälä ville.syrjala@linux.intel.com
The modes[] array contains pointers to modes on the connectors' mode lists, which are protected by dev->mode_config.mutex. Thus we need to extend modes[] the same protection or by the time we use it the elements may already be pointing to freed/reused memory.
Cc: stable@vger.kernel.org Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/10583 Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com --- drivers/gpu/drm/drm_client_modeset.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c index 871e4e2129d6..0683a129b362 100644 --- a/drivers/gpu/drm/drm_client_modeset.c +++ b/drivers/gpu/drm/drm_client_modeset.c @@ -777,6 +777,7 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width, unsigned int total_modes_count = 0; struct drm_client_offset *offsets; unsigned int connector_count = 0; + /* points to modes protected by mode_config.mutex */ struct drm_display_mode **modes; struct drm_crtc **crtcs; int i, ret = 0; @@ -845,7 +846,6 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width, drm_client_pick_crtcs(client, connectors, connector_count, crtcs, modes, 0, width, height); } - mutex_unlock(&dev->mode_config.mutex);
drm_client_modeset_release(client);
@@ -875,6 +875,7 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width, modeset->y = offset->y; } } + mutex_unlock(&dev->mode_config.mutex);
mutex_unlock(&client->modeset_mutex); out:
On Thu, Apr 04, 2024 at 11:33:25PM +0300, Ville Syrjala wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
The modes[] array contains pointers to modes on the connectors' mode lists, which are protected by dev->mode_config.mutex. Thus we need to extend modes[] the same protection or by the time we use it the elements may already be pointing to freed/reused memory.
Cc: stable@vger.kernel.org Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/10583 Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
Reviewed-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org
I tried looking for the proper Fixes tag, but it looks like it might be something like 386516744ba4 ("drm/fb: fix fbdev object model + cleanup properly.")
drivers/gpu/drm/drm_client_modeset.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/drm_client_modeset.c b/drivers/gpu/drm/drm_client_modeset.c index 871e4e2129d6..0683a129b362 100644 --- a/drivers/gpu/drm/drm_client_modeset.c +++ b/drivers/gpu/drm/drm_client_modeset.c @@ -777,6 +777,7 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width, unsigned int total_modes_count = 0; struct drm_client_offset *offsets; unsigned int connector_count = 0;
- /* points to modes protected by mode_config.mutex */ struct drm_display_mode **modes; struct drm_crtc **crtcs; int i, ret = 0;
@@ -845,7 +846,6 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width, drm_client_pick_crtcs(client, connectors, connector_count, crtcs, modes, 0, width, height); }
- mutex_unlock(&dev->mode_config.mutex);
drm_client_modeset_release(client); @@ -875,6 +875,7 @@ int drm_client_modeset_probe(struct drm_client_dev *client, unsigned int width, modeset->y = offset->y; } }
- mutex_unlock(&dev->mode_config.mutex);
mutex_unlock(&client->modeset_mutex); out: -- 2.43.2
On Fri, Apr 05, 2024 at 06:24:01AM +0300, Dmitry Baryshkov wrote:
On Thu, Apr 04, 2024 at 11:33:25PM +0300, Ville Syrjala wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
The modes[] array contains pointers to modes on the connectors' mode lists, which are protected by dev->mode_config.mutex. Thus we need to extend modes[] the same protection or by the time we use it the elements may already be pointing to freed/reused memory.
Cc: stable@vger.kernel.org Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/10583 Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
Reviewed-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org
I tried looking for the proper Fixes tag, but it looks like it might be something like 386516744ba4 ("drm/fb: fix fbdev object model + cleanup properly.")
The history is rather messy. I think it was originally completely lockless and broken, and got fixed piecemeal later in these: commit 7394371d8569 ("drm: Take lock around probes for drm_fb_helper_hotplug_event") commit 966a6a13c666 ("drm: Hold mode_config.lock to prevent hotplug whilst setting up crtcs")
commit e13a05831050 ("drm/fb-helper: Stop using mode_config.mutex for internals") looks to me like where the race might have been re-introduced. But didn't do a thorough analysis so not 100% sure. It's all rather ancient history by now so a Fixes tag doesn't seem all that useful anyway.
On Fri, 5 Apr 2024 at 22:17, Ville Syrjälä ville.syrjala@linux.intel.com wrote:
On Fri, Apr 05, 2024 at 06:24:01AM +0300, Dmitry Baryshkov wrote:
On Thu, Apr 04, 2024 at 11:33:25PM +0300, Ville Syrjala wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
The modes[] array contains pointers to modes on the connectors' mode lists, which are protected by dev->mode_config.mutex. Thus we need to extend modes[] the same protection or by the time we use it the elements may already be pointing to freed/reused memory.
Cc: stable@vger.kernel.org Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/10583 Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
Reviewed-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org
I tried looking for the proper Fixes tag, but it looks like it might be something like 386516744ba4 ("drm/fb: fix fbdev object model + cleanup properly.")
The history is rather messy. I think it was originally completely lockless and broken, and got fixed piecemeal later in these: commit 7394371d8569 ("drm: Take lock around probes for drm_fb_helper_hotplug_event") commit 966a6a13c666 ("drm: Hold mode_config.lock to prevent hotplug whilst setting up crtcs")
commit e13a05831050 ("drm/fb-helper: Stop using mode_config.mutex for internals") looks to me like where the race might have been re-introduced. But didn't do a thorough analysis so not 100% sure. It's all rather ancient history by now so a Fixes tag doesn't seem all that useful anyway.
Well, you have added stable to cc list, so you expect to have this patch backported. Then it should either have a kernel version as a 'starting' point or a Fixes tag to assist the sable team.
On Fri, Apr 05, 2024 at 11:39:33PM +0300, Dmitry Baryshkov wrote:
On Fri, 5 Apr 2024 at 22:17, Ville Syrjälä ville.syrjala@linux.intel.com wrote:
On Fri, Apr 05, 2024 at 06:24:01AM +0300, Dmitry Baryshkov wrote:
On Thu, Apr 04, 2024 at 11:33:25PM +0300, Ville Syrjala wrote:
From: Ville Syrjälä ville.syrjala@linux.intel.com
The modes[] array contains pointers to modes on the connectors' mode lists, which are protected by dev->mode_config.mutex. Thus we need to extend modes[] the same protection or by the time we use it the elements may already be pointing to freed/reused memory.
Cc: stable@vger.kernel.org Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/10583 Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com
Reviewed-by: Dmitry Baryshkov dmitry.baryshkov@linaro.org
I tried looking for the proper Fixes tag, but it looks like it might be something like 386516744ba4 ("drm/fb: fix fbdev object model + cleanup properly.")
The history is rather messy. I think it was originally completely lockless and broken, and got fixed piecemeal later in these: commit 7394371d8569 ("drm: Take lock around probes for drm_fb_helper_hotplug_event") commit 966a6a13c666 ("drm: Hold mode_config.lock to prevent hotplug whilst setting up crtcs")
commit e13a05831050 ("drm/fb-helper: Stop using mode_config.mutex for internals") looks to me like where the race might have been re-introduced. But didn't do a thorough analysis so not 100% sure. It's all rather ancient history by now so a Fixes tag doesn't seem all that useful anyway.
Well, you have added stable to cc list, so you expect to have this patch backported. Then it should either have a kernel version as a 'starting' point or a Fixes tag to assist the sable team.
It'll get backported just fine without either.
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