[PATCH AUTOSEL 6.0 14/77] micrel: ksz8851: fixes struct pointer issue

Sasha Levin
2022-10-09T22:09:59Z

From: Jerry Ray <jerry.ray@microchip.com>

[ Upstream commit fef5de753ff01887cfa50990532c3890fccb9338 ]

Issue found during code review. This bug has no impact as long as the
ks8851_net structure is the first element of the ks8851_net_spi structure.
As long as the offset to the ks8851_net struct is zero, the container_of()
macro is subtracting 0 and therefore no damage done. But if the
ks8851_net_spi struct is ever modified such that the ks8851_net struct
within it is no longer the first element of the struct, then the bug would
manifest itself and cause problems.

struct ks8851_net is contained within ks8851_net_spi.
ks is contained within kss.
kss is the priv_data of the netdev structure.

Signed-off-by: Jerry Ray <jerry.ray@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/ethernet/micrel/ks8851_spi.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/micrel/ks8851_spi.c b/drivers/net/ethernet/micrel/ks8851_spi.c
index 82d55fc27edc..70bc7253454f 100644
--- a/drivers/net/ethernet/micrel/ks8851_spi.c
+++ b/drivers/net/ethernet/micrel/ks8851_spi.c
@@ -413,7 +413,8 @@ static int ks8851_probe_spi(struct spi_device *spi)

spi->bits_per_word = 8;

- ks = netdev_priv(netdev);
+ kss = netdev_priv(netdev);
+ ks = &kss->ks8851;

ks->lock = ks8851_lock_spi;
ks->unlock = ks8851_unlock_spi;
@@ -433,8 +434,6 @@ static int ks8851_probe_spi(struct spi_device *spi)
IRQ_RXPSI) /* RX process stop */
ks->rc_ier = STD_IRQ;

- kss = to_ks8851_spi(ks);
-
kss->spidev = spi;
mutex_init(&kss->lock);
INIT_WORK(&kss->tx_work, ks8851_tx_work);
--
2.35.1