Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 5.12 43/45] sit: proper dev_{hold|put} in ndo_[un]init methods | Date | Thu, 20 May 2021 11:22:31 +0200 |
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From: Eric Dumazet <edumazet@google.com>
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@google.com> Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/ipv6/sit.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)
--- a/net/ipv6/sit.c +++ b/net/ipv6/sit.c @@ -218,8 +218,6 @@ static int ipip6_tunnel_create(struct ne ipip6_tunnel_clone_6rd(dev, sitn); - dev_hold(dev); - ipip6_tunnel_link(sitn, t); return 0; @@ -1456,7 +1454,7 @@ static int ipip6_tunnel_init(struct net_ dev->tstats = NULL; return err; } - + dev_hold(dev); return 0; }
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