netdev - [PATCH v1 iwl-net] igc: unregister netdev when igc_led_setup() fails in igc

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Message-ID: <20250906055239.29396-1-enjuk@amazon.com>
Date: Sat, 6 Sep 2025 14:51:30 +0900
From: Kohei Enju <enjuk@...zon.com>
To: <intel-wired-lan@...ts.osuosl.org>, <netdev@...r.kernel.org>
CC: Tony Nguyen <anthony.l.nguyen@...el.com>, Przemek Kitszel
	<przemyslaw.kitszel@...el.com>, Andrew Lunn <andrew+netdev@...n.ch>, "David
 S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, "Jakub
 Kicinski" <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, Kurt Kanzenbach
	<kurt@...utronix.de>, <kohei.enju@...il.com>, Kohei Enju <enjuk@...zon.com>
Subject: [PATCH v1 iwl-net] igc: unregister netdev when igc_led_setup() fails in igc_probe()

Currently igc_probe() doesn't unregister netdev when igc_led_setup()
fails, causing BUG_ON() in free_netdev() and then kernel panics. [1]

This behavior can be tested using fault-injection framework. I used the
failslab feature to test the issue. [2]

Call unregister_netdev() when igc_led_setup() fails to avoid the kernel
panic.

[1]
 kernel BUG at net/core/dev.c:12047!
 Oops: invalid opcode: 0000 [#1] SMP NOPTI
 CPU: 0 UID: 0 PID: 937 Comm: repro-igc-led-e Not tainted 6.17.0-rc4-enjuk-tnguy-00865-gc4940196ab02 #64 PREEMPT(voluntary)
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
 RIP: 0010:free_netdev+0x278/0x2b0
 [...]
 Call Trace:
  <TASK>
  igc_probe+0x370/0x910
  local_pci_probe+0x3a/0x80
  pci_device_probe+0xd1/0x200
 [...]

[2]
 #!/bin/bash -ex

 FAILSLAB_PATH=/sys/kernel/debug/failslab/
 DEVICE=0000:00:05.0
 START_ADDR=$(grep " igc_led_setup" /proc/kallsyms \
         | awk '{printf("0x%s", $1)}')
 END_ADDR=$(printf "0x%x" $((START_ADDR + 0x100)))

 echo $START_ADDR > $FAILSLAB_PATH/require-start
 echo $END_ADDR > $FAILSLAB_PATH/require-end
 echo 1 > $FAILSLAB_PATH/times
 echo 100 > $FAILSLAB_PATH/probability
 echo N > $FAILSLAB_PATH/ignore-gfp-wait

 echo $DEVICE > /sys/bus/pci/drivers/igc/bind

Fixes: ea578703b03d ("igc: Add support for LEDs on i225/i226")
Signed-off-by: Kohei Enju <enjuk@...zon.com>
---
 drivers/net/ethernet/intel/igc/igc_main.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index e79b14d50b24..95c415d0917d 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -7336,11 +7336,13 @@ static int igc_probe(struct pci_dev *pdev,
 	if (IS_ENABLED(CONFIG_IGC_LEDS)) {
 		err = igc_led_setup(adapter);
 		if (err)
-			goto err_register;
+			goto err_led_setup;
 	}
 
 	return 0;
 
+err_led_setup:
+	unregister_netdev(netdev);
 err_register:
 	igc_release_hw_control(adapter);
 	igc_ptp_stop(adapter);
-- 
2.48.1