[PATCH v3 0/2] a fix for connector modes leak in amdgpu driver

[PATCH v3 0/2] a fix for connector modes leak in amdgpu driver

[Fedor Pchelkin]

The first patch is a prerequisite exporting a convenient helper at
include/drm/modes.h used in the second one fixing a leak in amdgpu
driver.

v2: https://lore.kernel.org/dri-devel/20250819184636.232641-1-pchelkin@ispras.ru/
v1: https://lore.kernel.org/dri-devel/20250817094346.15740-1-pchelkin@ispras.ru/

Fedor Pchelkin (2):
  drm/modes: export drm_mode_remove() helper
  drm/amd/display: fix leak of probed modes

 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c |  6 +++++-
 drivers/gpu/drm/drm_connector.c                   |  8 +-------
 drivers/gpu/drm/drm_modes.c                       | 15 +++++++++++++++
 include/drm/drm_modes.h                           |  1 +
 4 files changed, 22 insertions(+), 8 deletions(-)

-- 
2.50.1

[PATCH v3 1/2] drm/modes: export drm_mode_remove() helper

[Fedor Pchelkin]

This functionality may be helpful in drivers so export it for reusability.

Found by Linux Verification Center (linuxtesting.org).

Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
---
 drivers/gpu/drm/drm_connector.c |  8 +-------
 drivers/gpu/drm/drm_modes.c     | 15 +++++++++++++++
 include/drm/drm_modes.h         |  1 +
 3 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
index 272d6254ea47..0a3933b6ceec 100644
--- a/drivers/gpu/drm/drm_connector.c
+++ b/drivers/gpu/drm/drm_connector.c
@@ -27,6 +27,7 @@
 #include <drm/drm_encoder.h>
 #include <drm/drm_file.h>
 #include <drm/drm_managed.h>
+#include <drm/drm_modes.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_print.h>
 #include <drm/drm_privacy_screen_consumer.h>
@@ -696,13 +697,6 @@ bool drm_connector_has_possible_encoder(struct drm_connector *connector,
 }
 EXPORT_SYMBOL(drm_connector_has_possible_encoder);
 
-static void drm_mode_remove(struct drm_connector *connector,
-			    struct drm_display_mode *mode)
-{
-	list_del(&mode->head);
-	drm_mode_destroy(connector->dev, mode);
-}
-
 /**
  * drm_connector_cec_phys_addr_invalidate - invalidate CEC physical address
  * @connector: connector undergoing CEC operation
diff --git a/drivers/gpu/drm/drm_modes.c b/drivers/gpu/drm/drm_modes.c
index e72f855fc495..6e021328f9c2 100644
--- a/drivers/gpu/drm/drm_modes.c
+++ b/drivers/gpu/drm/drm_modes.c
@@ -117,6 +117,21 @@ void drm_mode_probed_add(struct drm_connector *connector,
 }
 EXPORT_SYMBOL(drm_mode_probed_add);
 
+/**
+ * drm_mode_remove - remove a mode from the associated list and destroy it
+ * @connector: connector of the mode
+ * @mode: mode data
+ *
+ * Remove @mode from the associated list, then free @mode object itself.
+ */
+void drm_mode_remove(struct drm_connector *connector,
+		     struct drm_display_mode *mode)
+{
+	list_del(&mode->head);
+	drm_mode_destroy(connector->dev, mode);
+}
+EXPORT_SYMBOL(drm_mode_remove);
+
 enum drm_mode_analog {
 	DRM_MODE_ANALOG_NTSC, /* 525 lines, 60Hz */
 	DRM_MODE_ANALOG_PAL, /* 625 lines, 50Hz */
diff --git a/include/drm/drm_modes.h b/include/drm/drm_modes.h
index b9bb92e4b029..d7b66321f60d 100644
--- a/include/drm/drm_modes.h
+++ b/include/drm/drm_modes.h
@@ -460,6 +460,7 @@ int drm_mode_convert_umode(struct drm_device *dev,
 			   struct drm_display_mode *out,
 			   const struct drm_mode_modeinfo *in);
 void drm_mode_probed_add(struct drm_connector *connector, struct drm_display_mode *mode);
+void drm_mode_remove(struct drm_connector *connector, struct drm_display_mode *mode);
 void drm_mode_debug_printmodeline(const struct drm_display_mode *mode);
 bool drm_mode_is_420_only(const struct drm_display_info *display,
 			  const struct drm_display_mode *mode);
-- 
2.50.1

[PATCH v3 2/2] drm/amd/display: fix leak of probed modes

[Fedor Pchelkin]

amdgpu_dm_connector_ddc_get_modes() reinitializes a connector's probed
modes list without cleaning it up. First time it is called during the
driver's initialization phase, then via drm_mode_getconnector() ioctl.
The leaks observed with Kmemleak are as following:

unreferenced object 0xffff88812f91b200 (size 128):
  comm "(udev-worker)", pid 388, jiffies 4294695475
  hex dump (first 32 bytes):
    ac dd 07 00 80 02 70 0b 90 0b e0 0b 00 00 e0 01  ......p.........
    0b 07 10 07 5c 07 00 00 0a 00 00 00 00 00 00 00  ....\...........
  backtrace (crc 89db554f):
    __kmalloc_cache_noprof+0x3a3/0x490
    drm_mode_duplicate+0x8e/0x2b0
    amdgpu_dm_create_common_mode+0x40/0x150 [amdgpu]
    amdgpu_dm_connector_add_common_modes+0x336/0x488 [amdgpu]
    amdgpu_dm_connector_get_modes+0x428/0x8a0 [amdgpu]
    amdgpu_dm_initialize_drm_device+0x1389/0x17b4 [amdgpu]
    amdgpu_dm_init.cold+0x157b/0x1a1e [amdgpu]
    dm_hw_init+0x3f/0x110 [amdgpu]
    amdgpu_device_ip_init+0xcf4/0x1180 [amdgpu]
    amdgpu_device_init.cold+0xb84/0x1863 [amdgpu]
    amdgpu_driver_load_kms+0x15/0x90 [amdgpu]
    amdgpu_pci_probe+0x391/0xce0 [amdgpu]
    local_pci_probe+0xd9/0x190
    pci_call_probe+0x183/0x540
    pci_device_probe+0x171/0x2c0
    really_probe+0x1e1/0x890

Found by Linux Verification Center (linuxtesting.org).

Fixes: acc96ae0d127 ("drm/amd/display: set panel orientation before drm_dev_register")
Cc: stable@vger.kernel.org
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
---

v3: drop INIT_LIST_HEAD and use drm_edid_connector_update() (Melissa Wen)
v2: use exported drm_mode_remove() (Mario Limonciello)

 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index a0ca3b2c6bd8..12685966186b 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -8230,10 +8230,14 @@ static void amdgpu_dm_connector_ddc_get_modes(struct drm_connector *connector,
 {
 	struct amdgpu_dm_connector *amdgpu_dm_connector =
 			to_amdgpu_dm_connector(connector);
+	struct drm_display_mode *mode, *t;
 
 	if (drm_edid) {
 		/* empty probed_modes */
-		INIT_LIST_HEAD(&connector->probed_modes);
+		list_for_each_entry_safe(mode, t, &connector->probed_modes, head)
+			drm_mode_remove(connector, mode);
+
+		drm_edid_connector_update(connector, drm_edid);
 		amdgpu_dm_connector->num_modes =
 				drm_edid_connector_add_modes(connector);
 
-- 
2.50.1