[PATCH v4] ieee802154: cc2520: fix FIFOP work use-after-free

The FIFOP interrupt handler queues cc2520_fifop_irqwork.  On removal,
cc2520_remove() only flushes the work.  The devm-managed FIFOP IRQ
remains active until after ->remove() returns and can queue the work
again after that flush, allowing it to run after the private data is
released.

Disable the work with disable_work_sync() instead of flushing it, so
the handler can no longer queue it once removal begins.  Destroy the
buffer mutex last, since the worker and the stop callback invoked
through ieee802154_unregister_hw() both take it.

Found by an in-house static analysis tool.

Fixes: 0da6bc8cc341 ("ieee802154: cc2520: adds driver for TI CC2520 radio")
Cc: stable@vger.kernel.org # v6.10+
Suggested-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Assisted-by: Codex:gpt-5.6
Signed-off-by: Fan Wu <redacted>
---
Changes in v4:
- Drop the erroneous registration-failure patch.
- Keep the unchanged FIFOP removal-path fix.

 drivers/net/ieee802154/cc2520.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ieee802154/cc2520.c b/drivers/net/ieee802154/cc2520.c
index 2b70341..abfcfe0 100644
--- a/drivers/net/ieee802154/cc2520.c
+++ b/drivers/net/ieee802154/cc2520.c

@@ -1156,11 +1156,10 @@ static void cc2520_remove(struct spi_device *spi)
 {
 	struct cc2520_private *priv = spi_get_drvdata(spi);
 
-	mutex_destroy(&priv->buffer_mutex);
-	flush_work(&priv->fifop_irqwork);
-
+	disable_work_sync(&priv->fifop_irqwork);
 	ieee802154_unregister_hw(priv->hw);
 	ieee802154_free_hw(priv->hw);
+	mutex_destroy(&priv->buffer_mutex);
 }
 
 static const struct spi_device_id cc2520_ids[] = {

-- 
2.34.1