Re: [PATCH] net: sfp: Fix memory leak of hwmon_name on hwmon registration failure

[krishan mohan]

Hi All,

Please find v2 of this patch. 

Changes since v1: - Move hwmon_name cleanup to sfp_hwmon_remove(). - Free hwmon_name independently of hwmon_dev.

---
v2:
- Move hwmon_name cleanup to sfp_hwmon_remove().
- Free hwmon_name independently of hwmon_dev.
---
 drivers/net/phy/sfp.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index f52020673..bfa2b821f 100644
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -1916,7 +1916,11 @@ static void sfp_hwmon_remove(struct sfp *sfp)
  if (!IS_ERR_OR_NULL(sfp->hwmon_dev)) {
  hwmon_device_unregister(sfp->hwmon_dev);
  sfp->hwmon_dev = NULL;
+ }
+
+ if (!IS_ERR_OR_NULL(sfp->hwmon_name)) {
  kfree(sfp->hwmon_name);
+ sfp->hwmon_name = NULL;
  }
 }
 
--

Thanks&Regards

Krishan Mohan Singh

On Wed, Aug 5, 2026 at 5:28 PM Andrew Lunn <andrew@xxxxxxx> wrote:

On Wed, Aug 05, 2026 at 10:06:43AM +0530, Krishan Singh wrote:
>     hwmon_sanitize_name() allocates sfp->hwmon_name before
>     hwmon_device_register_with_info() is called. If the registration
>     fails, sfp->hwmon_dev is left as an error pointer while
>     sfp->hwmon_name remains allocated.
>
>     Later, when the SFP module is removed, sfp_hwmon_remove() is still
>     called. However, it frees sfp->hwmon_name only when
>     !IS_ERR_OR_NULL(sfp->hwmon_dev) is true. Since sfp->hwmon_dev is an
>     error pointer in the failure case, the cleanup block is skipped and
>     hwmon_name is leaked.
>
>     Fix this by cleaning up hwmon_name independently of hwmon_dev.
>     Continue to unregister the hwmon device only when hwmon_dev is valid,
>     but free hwmon_name whenever it is a valid allocated pointer.
>
>     Fixes: 3f118c449c8e ("net: sfp: use hwmon_sanitize_name()")
>     Suggested-by: Andrew Lunn <andrew@xxxxxxx>
>     Signed-off-by: Krishan Singh <krishanmohan298@xxxxxxxxx>
> ---

Please read

https://docs.kernel.org/process/submitting-patches.html

There should be a version number in the Subject: line, and under the
--- a version history.

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

For netdev, we want the tree to be indicated in the Subject: line. For
this patch i would suggest net-next.

    Andrew

---
pw-bot: cr

From 9aab7f7e86228f708a9a968b756c83516b0ce817 Mon Sep 17 00:00:00 2001
From: Krishan Singh <krishanmohan298@xxxxxxxxx>
Date: Wed, 5 Aug 2026 10:04:47 +0530
Subject: [PATCH net-next v2] net: sfp: fix hwmon_name memory leak on hwmon
 registration failure

hwmon_sanitize_name() allocates sfp->hwmon_name before
hwmon_device_register_with_info() is called. If the registration
fails, sfp->hwmon_dev is left pointing to an error while
sfp->hwmon_name remains allocated.

Later, when the SFP module is removed, sfp_hwmon_remove() only frees
hwmon_name when hwmon_dev is valid. As a result, hwmon_name is leaked
if hwmon_device_register_with_info() fails.

Free hwmon_name independently of hwmon_dev. Continue to unregister the
hwmon device only when hwmon_dev was successfully registered.

Fixes: 3f118c449c8e ("net: sfp: use hwmon_sanitize_name()")
Suggested-by: Andrew Lunn <andrew@xxxxxxx>
Signed-off-by: Krishan Singh <krishanmohan298@xxxxxxxxx>

---
v2:
- Move hwmon_name cleanup to sfp_hwmon_remove().
- Free hwmon_name independently of hwmon_dev.
---
 drivers/net/phy/sfp.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/net/phy/sfp.c b/drivers/net/phy/sfp.c
index f52020673..bfa2b821f 100644
--- a/drivers/net/phy/sfp.c
+++ b/drivers/net/phy/sfp.c
@@ -1916,7 +1916,11 @@ static void sfp_hwmon_remove(struct sfp *sfp)
 	if (!IS_ERR_OR_NULL(sfp->hwmon_dev)) {
 		hwmon_device_unregister(sfp->hwmon_dev);
 		sfp->hwmon_dev = NULL;
+	}
+
+	if (!IS_ERR_OR_NULL(sfp->hwmon_name)) {
 		kfree(sfp->hwmon_name);
+		sfp->hwmon_name = NULL;
 	}
 }
 
-- 
2.34.1