From cfa98ffc42f16a432b77e438e2fefcdb942eeb04 Mon Sep 17 00:00:00 2001 From: Lin Ma Date: Thu, 11 Nov 2021 22:14:02 +0800 Subject: [PATCH] hamradio: remove needs_free_netdev to avoid UAF 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 Link: https://lore.kernel.org/r/20211111141402.7551-1-linma@zju.edu.cn Signed-off-by: Jakub Kicinski Signed-off-by: Xu Jia Signed-off-by: Greg Kroah-Hartman --- drivers/net/hamradio/6pack.c | 1 - 1 file changed, 1 deletion(-) diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c index 82507a688efe..83dc1c2c3b84 100644 --- a/drivers/net/hamradio/6pack.c +++ b/drivers/net/hamradio/6pack.c @@ -311,7 +311,6 @@ static void sp_setup(struct net_device *dev) { /* 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;