This is a note to let you know that I've just added the patch titled dccp: don't duplicate ccid when cloning dccp sock 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: dccp-don-t-duplicate-ccid-when-cloning-dccp-sock.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 d9ea761fdd197351890418acd462c51f241014a7 Mon Sep 17 00:00:00 2001 From: "Lin, Zhenpeng" <zplin@xxxxxxx> Date: Wed, 8 Sep 2021 03:40:59 +0000 Subject: dccp: don't duplicate ccid when cloning dccp sock From: Lin, Zhenpeng <zplin@xxxxxxx> commit d9ea761fdd197351890418acd462c51f241014a7 upstream. Commit 2677d2067731 ("dccp: don't free ccid2_hc_tx_sock ...") fixed a UAF but reintroduced CVE-2017-6074. When the sock is cloned, two dccps_hc_tx_ccid will reference to the same ccid. So one can free the ccid object twice from two socks after cloning. This issue was found by "Hadar Manor" as well and assigned with CVE-2020-16119, which was fixed in Ubuntu's kernel. So here I port the patch from Ubuntu to fix it. The patch prevents cloned socks from referencing the same ccid. Fixes: 2677d2067731410 ("dccp: don't free ccid2_hc_tx_sock ...") Signed-off-by: Zhenpeng Lin <zplin@xxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/dccp/minisocks.c | 2 ++ 1 file changed, 2 insertions(+) --- a/net/dccp/minisocks.c +++ b/net/dccp/minisocks.c @@ -98,6 +98,8 @@ struct sock *dccp_create_openreq_child(c newdp->dccps_role = DCCP_ROLE_SERVER; newdp->dccps_hc_rx_ackvec = NULL; newdp->dccps_service_list = NULL; + newdp->dccps_hc_rx_ccid = NULL; + newdp->dccps_hc_tx_ccid = NULL; newdp->dccps_service = dreq->dreq_service; newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo; newdp->dccps_timestamp_time = dreq->dreq_timestamp_time; Patches currently in stable-queue which might be from zplin@xxxxxxx are queue-4.9/dccp-don-t-duplicate-ccid-when-cloning-dccp-sock.patch