This is a note to let you know that I've just added the patch titled sit: proper dev_{hold|put} in ndo_[un]init methods to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: sit-proper-dev_-hold-put-in-ndo_init-methods.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 6289a98f0817a4a457750d6345e754838eae9439 Mon Sep 17 00:00:00 2001 From: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Mon, 29 Mar 2021 12:25:22 -0700 Subject: sit: proper dev_{hold|put} in ndo_[un]init methods From: Eric Dumazet <edumazet@xxxxxxxxxx> commit 6289a98f0817a4a457750d6345e754838eae9439 upstream. After adopting CONFIG_PCPU_DEV_REFCNT=n option, syzbot was able to trigger a warning [1] Issue here is that: - all dev_put() should be paired with a corresponding prior dev_hold(). - A driver doing a dev_put() in its ndo_uninit() MUST also do a dev_hold() in its ndo_init(), only when ndo_init() is returning 0. Otherwise, register_netdevice() would call ndo_uninit() in its error path and release a refcount too soon. Fixes: 919067cc845f ("net: add CONFIG_PCPU_DEV_REFCNT") Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/ipv6/sit.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -209,8 +209,6 @@ static int ipip6_tunnel_create(struct ne ipip6_tunnel_clone_6rd(dev, sitn); - dev_hold(dev); - ipip6_tunnel_link(sitn, t); return 0; @@ -1400,7 +1398,7 @@ static int ipip6_tunnel_init(struct net_ dev->tstats = NULL; return err; } - + dev_hold(dev); return 0; } Patches currently in stable-queue which might be from edumazet@xxxxxxxxxx are queue-4.9/ip6_tunnel-sit-proper-dev_-hold-put-in-ndo_init-methods.patch queue-4.9/sit-proper-dev_-hold-put-in-ndo_init-methods.patch queue-4.9/ip6_vti-proper-dev_-hold-put-in-ndo_-un-init-methods.patch queue-4.9/ipv6-remove-extra-dev_hold-for-fallback-tunnels.patch