[PATCH] net: stmmac: release MDIO node if bus data allocation fails

[PATCH] net: stmmac: release MDIO node if bus data allocation fails

[Wentao Liang]

stmmac_mdio_setup() looks up the MDIO device tree node and stores it in
plat->mdio_node before allocating plat->mdio_bus_data. If that allocation
fails, the function returns -ENOMEM without dropping the node reference.

The caller jumps to error_put_phy on this error, which only releases
plat->phy_node and never reaches error_put_mdio, so the reference taken
for the MDIO node is lost. Drop it before returning.

Fixes: 1a981c0586c0 ("net: stmmac: Make MDIO bus reset optional")
Cc: stable@vger.kernel.org
Assisted-by: DeepSeek-V4.1-Flash and OpenAI Codex
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 3ea16d618215..36f31bad11ca 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -355,8 +355,10 @@ static int stmmac_mdio_setup(struct plat_stmmacenet_data *plat,
 		plat->mdio_bus_data = devm_kzalloc(dev,
 						   sizeof(*plat->mdio_bus_data),
 						   GFP_KERNEL);
-		if (!plat->mdio_bus_data)
+		if (!plat->mdio_bus_data) {
+			of_node_put(plat->mdio_node);
 			return -ENOMEM;
+		}
 
 		plat->mdio_bus_data->needs_reset = true;
 	}
-- 
2.34.1

Re: [PATCH] net: stmmac: release MDIO node if bus data allocation fails

[netdev-bot+sinfo]

Hi!

This is an automated message. This series looks like a fix, but its
commit messages seem to be missing some information:

 - How the issue was discovered, e.g. hit in production, hit during
   development, syzbot report, manual code inspection, LLM or static
   analysis tool scan.

 - Whether the issue was actually triggered, or is only theoretical
   (e.g. found by code inspection). If it was triggered please include
   the symptoms, like the stack trace or error messages.

 - What hardware the change was tested on. For driver fixes please
   mention the device (and if relevant firmware version) used for
   testing, or say that the change was not tested on real hardware.

Please do not repost the series just to address the above. Instead,
reply to this email with the missing information, so that reviewers
can take it into account. If the series needs another revision for
other reasons, please include the information in the commit messages
then.

The evaluation is done by an LLM so it may be wrong, if you think
that is the case please reply and explain.