[PATCH] net: dsa: Fix error handling in dsa_port_parse_of

[PATCH] net: dsa: Fix error handling in dsa_port_parse_of

[Ma Ke]

When of_find_net_device_by_node() successfully acquires a reference to
a network device but the subsequent call to dsa_port_parse_cpu()
fails, dsa_port_parse_of() returns without releasing the reference
count on the network device.

of_find_net_device_by_node() increments the reference count of the
returned structure, which should be balanced with a corresponding
put_device() when the reference is no longer needed.

Found by code review.

Cc: stable@vger.kernel.org
Fixes: 6ca80638b90c ("net: dsa: Use conduit and user terms")
Signed-off-by: Ma Ke <make24@iscas.ac.cn>
---
 net/dsa/dsa.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/net/dsa/dsa.c b/net/dsa/dsa.c
index 5b01a0e43ebe..632e0d716d62 100644
--- a/net/dsa/dsa.c
+++ b/net/dsa/dsa.c
@@ -1246,6 +1246,7 @@ static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
 	struct device_node *ethernet = of_parse_phandle(dn, "ethernet", 0);
 	const char *name = of_get_property(dn, "label", NULL);
 	bool link = of_property_read_bool(dn, "link");
+	int err;
 
 	dp->dn = dn;
 
@@ -1259,7 +1260,13 @@ static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
 			return -EPROBE_DEFER;
 
 		user_protocol = of_get_property(dn, "dsa-tag-protocol", NULL);
-		return dsa_port_parse_cpu(dp, conduit, user_protocol);
+		err = dsa_port_parse_cpu(dp, conduit, user_protocol);
+		if (err) {
+			put_device(conduit);
+			return err;
+		}
+
+		return 0;
 	}
 
 	if (link)
-- 
2.17.1

Re: [PATCH] net: dsa: Fix error handling in dsa_port_parse_of

[Andrew Lunn]

On Fri, Nov 21, 2025 at 11:51:30AM +0800, Ma Ke wrote:
> When of_find_net_device_by_node() successfully acquires a reference to
> a network device but the subsequent call to dsa_port_parse_cpu()
> fails, dsa_port_parse_of() returns without releasing the reference
> count on the network device.
> 
> of_find_net_device_by_node() increments the reference count of the
> returned structure, which should be balanced with a corresponding
> put_device() when the reference is no longer needed.
> 
> Found by code review.
> 
> Cc: stable@vger.kernel.org
> Fixes: 6ca80638b90c ("net: dsa: Use conduit and user terms")

Why did you pick this commit for the Fixes tag?

> @@ -1259,7 +1260,13 @@ static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
>  			return -EPROBE_DEFER;
>  
>  		user_protocol = of_get_property(dn, "dsa-tag-protocol", NULL);
> -		return dsa_port_parse_cpu(dp, conduit, user_protocol);
> +		err = dsa_port_parse_cpu(dp, conduit, user_protocol);
> +		if (err) {
> +			put_device(conduit);
> +			return err;
> +		}
> +
> +		return 0;
>  	}
>  
>  	if (link)
> -- 
> 2.17.1

You can simplify this to:

		err = dsa_port_parse_cpu(dp, conduit, user_protocol);
		if (err) 
			put_device(conduit);

		return err;

https://www.kernel.org/doc/html/latest/process/maintainer-netdev.html

    Andrew

---
pw-bot: cr

Re: [PATCH] net: dsa: Fix error handling in dsa_port_parse_of

[kernel test robot]

Hi Ma,

kernel test robot noticed the following build errors:

[auto build test ERROR on net-next/main]
[also build test ERROR on net/main linus/master v6.18-rc6 next-20251121]
[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/Ma-Ke/net-dsa-Fix-error-handling-in-dsa_port_parse_of/20251121-115449
base:   net-next/main
patch link:    https://lore.kernel.org/r/20251121035130.16020-1-make24%40iscas.ac.cn
patch subject: [PATCH] net: dsa: Fix error handling in dsa_port_parse_of
config: i386-randconfig-004-20251121 (https://download.01.org/0day-ci/archive/20251122/202511220109.1PvI00Sr-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251122/202511220109.1PvI00Sr-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/202511220109.1PvI00Sr-lkp@intel.com/

All errors (new ones prefixed by >>):

>> net/dsa/dsa.c:1265:15: error: incompatible pointer types passing 'struct net_device *' to parameter of type 'struct device *' [-Werror,-Wincompatible-pointer-types]
    1265 |                         put_device(conduit);
         |                                    ^~~~~~~
   include/linux/device.h:1181:32: note: passing argument to parameter 'dev' here
    1181 | void put_device(struct device *dev);
         |                                ^
   1 error generated.


vim +1265 net/dsa/dsa.c

  1243	
  1244	static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
  1245	{
  1246		struct device_node *ethernet = of_parse_phandle(dn, "ethernet", 0);
  1247		const char *name = of_get_property(dn, "label", NULL);
  1248		bool link = of_property_read_bool(dn, "link");
  1249		int err;
  1250	
  1251		dp->dn = dn;
  1252	
  1253		if (ethernet) {
  1254			struct net_device *conduit;
  1255			const char *user_protocol;
  1256	
  1257			conduit = of_find_net_device_by_node(ethernet);
  1258			of_node_put(ethernet);
  1259			if (!conduit)
  1260				return -EPROBE_DEFER;
  1261	
  1262			user_protocol = of_get_property(dn, "dsa-tag-protocol", NULL);
  1263			err = dsa_port_parse_cpu(dp, conduit, user_protocol);
  1264			if (err) {
> 1265				put_device(conduit);
  1266				return err;
  1267			}
  1268	
  1269			return 0;
  1270		}
  1271	
  1272		if (link)
  1273			return dsa_port_parse_dsa(dp);
  1274	
  1275		return dsa_port_parse_user(dp, name);
  1276	}
  1277	

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

Re: [PATCH] net: dsa: Fix error handling in dsa_port_parse_of

[kernel test robot]

Hi Ma,

kernel test robot noticed the following build errors:

[auto build test ERROR on net-next/main]
[also build test ERROR on net/main linus/master v6.18-rc6 next-20251121]
[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/Ma-Ke/net-dsa-Fix-error-handling-in-dsa_port_parse_of/20251121-115449
base:   net-next/main
patch link:    https://lore.kernel.org/r/20251121035130.16020-1-make24%40iscas.ac.cn
patch subject: [PATCH] net: dsa: Fix error handling in dsa_port_parse_of
config: i386-allmodconfig (https://download.01.org/0day-ci/archive/20251122/202511220203.nggER5yL-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/20251122/202511220203.nggER5yL-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/202511220203.nggER5yL-lkp@intel.com/

All errors (new ones prefixed by >>):

   net/dsa/dsa.c: In function 'dsa_port_parse_of':
>> net/dsa/dsa.c:1265:36: error: passing argument 1 of 'put_device' from incompatible pointer type [-Wincompatible-pointer-types]
    1265 |                         put_device(conduit);
         |                                    ^~~~~~~
         |                                    |
         |                                    struct net_device *
   In file included from net/dsa/dsa.c:10:
   include/linux/device.h:1181:32: note: expected 'struct device *' but argument is of type 'struct net_device *'
    1181 | void put_device(struct device *dev);
         |                 ~~~~~~~~~~~~~~~^~~


vim +/put_device +1265 net/dsa/dsa.c

  1243	
  1244	static int dsa_port_parse_of(struct dsa_port *dp, struct device_node *dn)
  1245	{
  1246		struct device_node *ethernet = of_parse_phandle(dn, "ethernet", 0);
  1247		const char *name = of_get_property(dn, "label", NULL);
  1248		bool link = of_property_read_bool(dn, "link");
  1249		int err;
  1250	
  1251		dp->dn = dn;
  1252	
  1253		if (ethernet) {
  1254			struct net_device *conduit;
  1255			const char *user_protocol;
  1256	
  1257			conduit = of_find_net_device_by_node(ethernet);
  1258			of_node_put(ethernet);
  1259			if (!conduit)
  1260				return -EPROBE_DEFER;
  1261	
  1262			user_protocol = of_get_property(dn, "dsa-tag-protocol", NULL);
  1263			err = dsa_port_parse_cpu(dp, conduit, user_protocol);
  1264			if (err) {
> 1265				put_device(conduit);
  1266				return err;
  1267			}
  1268	
  1269			return 0;
  1270		}
  1271	
  1272		if (link)
  1273			return dsa_port_parse_dsa(dp);
  1274	
  1275		return dsa_port_parse_user(dp, name);
  1276	}
  1277	

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

Re: [PATCH] net: dsa: Fix error handling in dsa_port_parse_of

[Markus Elfring]

…
> returned structure, which should be balanced with a corresponding
> put_device() when the reference is no longer needed.
…

* Would a corresponding imperative wording become helpful for an improved change description?
  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.18-rc6#n94

* How do you think about to omit an extra check for the variable “err”
  in the affected if branch because it can always be returned here?

* Would it be helpful to append parentheses to the function name in the summary phrase?


Regards,
Markus

Re: [PATCH] net: dsa: Fix error handling in dsa_port_parse_of

[Greg KH]

On Sat, Nov 22, 2025 at 08:58:12PM +0100, Markus Elfring wrote:
> …
> > returned structure, which should be balanced with a corresponding
> > put_device() when the reference is no longer needed.
> …
> 
> * Would a corresponding imperative wording become helpful for an improved change description?
>   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.18-rc6#n94
> 
> * How do you think about to omit an extra check for the variable “err”
>   in the affected if branch because it can always be returned here?
> 
> * Would it be helpful to append parentheses to the function name in the summary phrase?
> 
> 
> Regards,
> Markus
> 


Hi,

This is the semi-friendly patch-bot of Greg Kroah-Hartman.

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Patch submitter, please ignore Markus's suggestion; you do not need to
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