[PATCH] drm/of: Fix device node reference leak in drm_of_panel_bridge_remove

[PATCH] drm/of: Fix device node reference leak in drm_of_panel_bridge_remove

[Miaoqian Lin]

of_graph_get_remote_node() returns a device node
with its reference count incremented. The caller is responsible for
releasing this reference when the node is no longer needed.

Add of_node_put(remote) to fix the reference leak.

Found via static analysis.

Fixes: c70087e8f16f ("drm/drm_of: add drm_of_panel_bridge_remove function")
Cc: stable@vger.kernel.org
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
---
 include/drm/drm_of.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/drm/drm_of.h b/include/drm/drm_of.h
index 7f0256dae3f1..5940b1cd542b 100644
--- a/include/drm/drm_of.h
+++ b/include/drm/drm_of.h
@@ -171,6 +171,7 @@ static inline int drm_of_panel_bridge_remove(const struct device_node *np,
 		return -ENODEV;
 
 	bridge = of_drm_find_bridge(remote);
+	of_node_put(remote);
 	drm_panel_bridge_remove(bridge);
 
 	return 0;
-- 
2.39.5 (Apple Git-154)

Re: [PATCH] drm/of: Fix device node reference leak in drm_of_panel_bridge_remove

[kernel test robot]

Hi Miaoqian,

kernel test robot noticed the following build errors:

[auto build test ERROR on drm-misc/drm-misc-next]
[also build test ERROR on linus/master v6.18-rc3 next-20251028]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Miaoqian-Lin/drm-of-Fix-device-node-reference-leak-in-drm_of_panel_bridge_remove/20251028-141134
base:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link:    https://lore.kernel.org/r/20251028060918.65688-1-linmq006%40gmail.com
patch subject: [PATCH] drm/of: Fix device node reference leak in drm_of_panel_bridge_remove
config: mips-randconfig-r072-20251028 (https://download.01.org/0day-ci/archive/20251028/202510282123.AjUbRs11-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project e1ae12640102fd2b05bc567243580f90acb1135f)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251028/202510282123.AjUbRs11-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510282123.AjUbRs11-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from drivers/gpu/drm/drm_bridge.c:37:
>> include/drm/drm_of.h:174:2: error: call to undeclared function 'of_node_put'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     174 |         of_node_put(remote);
         |         ^
   1 error generated.
--
   In file included from drivers/gpu/drm/panel/panel-magnachip-d53e6ea8966.c:10:
>> include/drm/drm_of.h:174:2: error: call to undeclared function 'of_node_put'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     174 |         of_node_put(remote);
         |         ^
   In file included from drivers/gpu/drm/panel/panel-magnachip-d53e6ea8966.c:13:
   In file included from include/linux/backlight.h:13:
   In file included from include/linux/fb.h:5:
   In file included from include/uapi/linux/fb.h:6:
   In file included from include/linux/i2c.h:21:
   In file included from include/linux/irqdomain.h:14:
>> include/linux/of.h:129:13: error: conflicting types for 'of_node_put'
     129 | extern void of_node_put(struct device_node *node);
         |             ^
   include/drm/drm_of.h:174:2: note: previous implicit declaration is here
     174 |         of_node_put(remote);
         |         ^
   2 errors generated.


vim +/of_node_put +174 include/drm/drm_of.h

   153	
   154	/*
   155	 * drm_of_panel_bridge_remove - remove panel bridge
   156	 * @np: device tree node containing panel bridge output ports
   157	 *
   158	 * Remove the panel bridge of a given DT node's port and endpoint number
   159	 *
   160	 * Returns zero if successful, or one of the standard error codes if it fails.
   161	 */
   162	static inline int drm_of_panel_bridge_remove(const struct device_node *np,
   163						     int port, int endpoint)
   164	{
   165	#if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_DRM_PANEL_BRIDGE)
   166		struct drm_bridge *bridge;
   167		struct device_node *remote;
   168	
   169		remote = of_graph_get_remote_node(np, port, endpoint);
   170		if (!remote)
   171			return -ENODEV;
   172	
   173		bridge = of_drm_find_bridge(remote);
 > 174		of_node_put(remote);
   175		drm_panel_bridge_remove(bridge);
   176	
   177		return 0;
   178	#else
   179		return -EINVAL;
   180	#endif
   181	}
   182	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH] drm/of: Fix device node reference leak in drm_of_panel_bridge_remove

[kernel test robot]

Hi Miaoqian,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-misc/drm-misc-next]
[also build test WARNING on linus/master v6.18-rc3 next-20251028]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Miaoqian-Lin/drm-of-Fix-device-node-reference-leak-in-drm_of_panel_bridge_remove/20251028-141134
base:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link:    https://lore.kernel.org/r/20251028060918.65688-1-linmq006%40gmail.com
patch subject: [PATCH] drm/of: Fix device node reference leak in drm_of_panel_bridge_remove
config: x86_64-randconfig-161-20251028 (https://download.01.org/0day-ci/archive/20251028/202510282155.MdnvC7YI-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251028/202510282155.MdnvC7YI-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510282155.MdnvC7YI-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from drivers/gpu/drm/tiny/arcpgu.c:23:
   include/drm/drm_of.h: In function 'drm_of_panel_bridge_remove':
   include/drm/drm_of.h:174:9: error: implicit declaration of function 'of_node_put' [-Wimplicit-function-declaration]
     174 |         of_node_put(remote);
         |         ^~~~~~~~~~~
   In file included from include/linux/of_reserved_mem.h:6,
                    from drivers/gpu/drm/tiny/arcpgu.c:28:
   include/linux/of.h: At top level:
>> include/linux/of.h:129:13: warning: conflicting types for 'of_node_put'; have 'void(struct device_node *)'
     129 | extern void of_node_put(struct device_node *node);
         |             ^~~~~~~~~~~
   include/drm/drm_of.h:174:9: note: previous implicit declaration of 'of_node_put' with type 'void(struct device_node *)'
     174 |         of_node_put(remote);
         |         ^~~~~~~~~~~


vim +129 include/linux/of.h

0829f6d1f69e4f Pantelis Antoniou 2013-12-13  126  
0f22dd395fc473 Grant Likely      2012-02-15  127  #ifdef CONFIG_OF_DYNAMIC
0f22dd395fc473 Grant Likely      2012-02-15  128  extern struct device_node *of_node_get(struct device_node *node);
0f22dd395fc473 Grant Likely      2012-02-15 @129  extern void of_node_put(struct device_node *node);
0f22dd395fc473 Grant Likely      2012-02-15  130  #else /* CONFIG_OF_DYNAMIC */
3ecdd0515287af Rob Herring       2011-12-13  131  /* Dummy ref counting routines - to be implemented later */
3ecdd0515287af Rob Herring       2011-12-13  132  static inline struct device_node *of_node_get(struct device_node *node)
3ecdd0515287af Rob Herring       2011-12-13  133  {
3ecdd0515287af Rob Herring       2011-12-13  134  	return node;
3ecdd0515287af Rob Herring       2011-12-13  135  }
0f22dd395fc473 Grant Likely      2012-02-15  136  static inline void of_node_put(struct device_node *node) { }
0f22dd395fc473 Grant Likely      2012-02-15  137  #endif /* !CONFIG_OF_DYNAMIC */
9448e55d032d99 Jonathan Cameron  2024-02-25  138  DEFINE_FREE(device_node, struct device_node *, if (_T) of_node_put(_T))
3ecdd0515287af Rob Herring       2011-12-13  139  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [PATCH] drm/of: Fix device node reference leak in drm_of_panel_bridge_remove

[kernel test robot]

Hi Miaoqian,

kernel test robot noticed the following build warnings:

[auto build test WARNING on drm-misc/drm-misc-next]
[also build test WARNING on linus/master v6.18-rc3 next-20251028]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Miaoqian-Lin/drm-of-Fix-device-node-reference-leak-in-drm_of_panel_bridge_remove/20251028-141134
base:   git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
patch link:    https://lore.kernel.org/r/20251028060918.65688-1-linmq006%40gmail.com
patch subject: [PATCH] drm/of: Fix device node reference leak in drm_of_panel_bridge_remove
config: parisc-randconfig-002-20251028 (https://download.01.org/0day-ci/archive/20251028/202510282250.QkCSotB2-lkp@intel.com/config)
compiler: hppa-linux-gcc (GCC) 8.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251028/202510282250.QkCSotB2-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202510282250.QkCSotB2-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from drivers/gpu/drm/bridge/ti-dlpc3433.c:12:
   include/drm/drm_of.h: In function 'drm_of_panel_bridge_remove':
   include/drm/drm_of.h:174:2: error: implicit declaration of function 'of_node_put'; did you mean 'fwnode_init'? [-Werror=implicit-function-declaration]
     of_node_put(remote);
     ^~~~~~~~~~~
     fwnode_init
   In file included from include/linux/irqdomain.h:14,
                    from include/linux/i2c.h:21,
                    from drivers/gpu/drm/bridge/ti-dlpc3433.c:18:
   include/linux/of.h: At top level:
>> include/linux/of.h:129:13: warning: conflicting types for 'of_node_put'
    extern void of_node_put(struct device_node *node);
                ^~~~~~~~~~~
   In file included from drivers/gpu/drm/bridge/ti-dlpc3433.c:12:
   include/drm/drm_of.h:174:2: note: previous implicit declaration of 'of_node_put' was here
     of_node_put(remote);
     ^~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/of_node_put +129 include/linux/of.h

0829f6d1f69e4f Pantelis Antoniou 2013-12-13  126  
0f22dd395fc473 Grant Likely      2012-02-15  127  #ifdef CONFIG_OF_DYNAMIC
0f22dd395fc473 Grant Likely      2012-02-15  128  extern struct device_node *of_node_get(struct device_node *node);
0f22dd395fc473 Grant Likely      2012-02-15 @129  extern void of_node_put(struct device_node *node);
0f22dd395fc473 Grant Likely      2012-02-15  130  #else /* CONFIG_OF_DYNAMIC */
3ecdd0515287af Rob Herring       2011-12-13  131  /* Dummy ref counting routines - to be implemented later */
3ecdd0515287af Rob Herring       2011-12-13  132  static inline struct device_node *of_node_get(struct device_node *node)
3ecdd0515287af Rob Herring       2011-12-13  133  {
3ecdd0515287af Rob Herring       2011-12-13  134  	return node;
3ecdd0515287af Rob Herring       2011-12-13  135  }
0f22dd395fc473 Grant Likely      2012-02-15  136  static inline void of_node_put(struct device_node *node) { }
0f22dd395fc473 Grant Likely      2012-02-15  137  #endif /* !CONFIG_OF_DYNAMIC */
9448e55d032d99 Jonathan Cameron  2024-02-25  138  DEFINE_FREE(device_node, struct device_node *, if (_T) of_node_put(_T))
3ecdd0515287af Rob Herring       2011-12-13  139  

-- 
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https://github.com/intel/lkp-tests/wiki