From: Lin Ma linma@zju.edu.cn
commit 81b1d548d00bcd028303c4f3150fa753b9b8aa71 upstream.
The former patch "defer 6pack kfree after unregister_netdev" reorders the kfree of two buffer after the unregister_netdev to prevent the race condition. It also adds free_netdev() function in sixpack_close(), which is a direct copy from the similar code in mkiss_close().
However, in sixpack driver, the flag needs_free_netdev is set to true in sp_setup(), hence the unregister_netdev() will free the netdev automatically. Therefore, as the sp is netdev_priv, use-after-free occurs.
This patch removes the needs_free_netdev = true and just let the free_netdev to finish this deallocation task.
Fixes: 0b9111922b1f ("hamradio: defer 6pack kfree after unregister_netdev") Signed-off-by: Lin Ma linma@zju.edu.cn Link: https://lore.kernel.org/r/20211111141402.7551-1-linma@zju.edu.cn Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Ovidiu Panait ovidiu.panait@windriver.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/hamradio/6pack.c | 1 - 1 file changed, 1 deletion(-)
--- a/drivers/net/hamradio/6pack.c +++ b/drivers/net/hamradio/6pack.c @@ -311,7 +311,6 @@ static void sp_setup(struct net_device * { /* Finish setting up the DEVICE info. */ dev->netdev_ops = &sp_netdev_ops; - dev->needs_free_netdev = true; dev->mtu = SIXP_MTU; dev->hard_header_len = AX25_MAX_HEADER_LEN; dev->header_ops = &ax25_header_ops;