Re: [PATCH stable 5.15] tcp: add a missing nf_reset_ct() in 3WHS handling

[Greg KH <greg@kroah.com>]

On Thu, Jun 30, 2022 at 06:41:01PM -0700, Jakub Kicinski wrote:
> From: Eric Dumazet <edumazet@google.com>
> 
> commit 6f0012e35160cd08a53e46e3b3bbf724b92dfe68 upstream.
> 
> When the third packet of 3WHS connection establishment
> contains payload, it is added into socket receive queue
> without the XFRM check and the drop of connection tracking
> context.
> 
> This means that if the data is left unread in the socket
> receive queue, conntrack module can not be unloaded.
> 
> As most applications usually reads the incoming data
> immediately after accept(), bug has been hiding for
> quite a long time.
> 
> Commit 68822bdf76f1 ("net: generalize skb freeing
> deferral to per-cpu lists") exposed this bug because
> even if the application reads this data, the skb
> with nfct state could stay in a per-cpu cache for
> an arbitrary time, if said cpu no longer process RX softirqs.
> 
> Many thanks to Ilya Maximets for reporting this issue,
> and for testing various patches:
> https://lore.kernel.org/netdev/20220619003919.394622-1-i.maximets@ovn.org/
> 
> Note that I also added a missing xfrm4_policy_check() call,
> although this is probably not a big issue, as the SYN
> packet should have been dropped earlier.
> 
> Fixes: b59c270104f0 ("[NETFILTER]: Keep conntrack reference until IPsec policy checks are done")
> Reported-by: Ilya Maximets <i.maximets@ovn.org>
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Cc: Florian Westphal <fw@strlen.de>
> Cc: Pablo Neira Ayuso <pablo@netfilter.org>
> Cc: Steffen Klassert <steffen.klassert@secunet.com>
> Tested-by: Ilya Maximets <i.maximets@ovn.org>
> Reviewed-by: Ilya Maximets <i.maximets@ovn.org>
> Link: https://lore.kernel.org/r/20220623050436.1290307-1-edumazet@google.com
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
>  net/ipv4/tcp_ipv4.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)

Now queued up, thanks.

greg k-h