[PATCH] ieee802154: ca8210: fix cas_ctl leak on spi_async failure

[Shitalkumar Gandhi <shital.gandhi45@gmail.com>]

ca8210_spi_transfer() allocates cas_ctl with kzalloc_obj(GFP_ATOMIC)
and relies entirely on the SPI completion callback
ca8210_spi_transfer_complete() to free it.

The spi_async() API only invokes the completion callback on successful
submission.  On failure it returns a negative error code without ever
queuing the callback, which leaves cas_ctl and its embedded spi_message
and spi_transfer orphaned.  Every kfree(cas_ctl) in the driver is
inside the completion callback, so there is no other reclamation path.

ca8210_spi_transfer() is called from ca8210_spi_exchange(), the
interrupt handler ca8210_interrupt_handler(), and from the retry path
inside the completion callback itself.  The exchange and interrupt
handler paths loop on -EBUSY, so under sustained SPI bus contention
every retry iteration leaks a fresh cas_ctl (~600 bytes per
occurrence).

Fix it by freeing cas_ctl on the spi_async() error path.  While here,
correct the misleading error string: the function calls spi_async(),
not spi_sync().

Fixes: ded845a781a5 ("ieee802154: Add CA8210 IEEE 802.15.4 device driver")
Cc: stable@vger.kernel.org
Signed-off-by: Shitalkumar Gandhi <shitalkumar.gandhi@cambiumnetworks.com>
---
 drivers/net/ieee802154/ca8210.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ieee802154/ca8210.c b/drivers/net/ieee802154/ca8210.c
index ed4178155a5d..bf837adfebb2 100644
--- a/drivers/net/ieee802154/ca8210.c
+++ b/drivers/net/ieee802154/ca8210.c
@@ -919,9 +919,10 @@ static int ca8210_spi_transfer(
 	if (status < 0) {
 		dev_crit(
 			&spi->dev,
-			"status %d from spi_sync in write\n",
+			"status %d from spi_async in write\n",
 			status
 		);
+		kfree(cas_ctl);
 	}
 
 	return status;
-- 
2.25.1