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dccp: don't duplicate ccid when cloning dccp sock

Message ID D95F1297-95A1-4AC9-B0C2-803C453B1BAE@psu.edu (mailing list archive)
State Superseded
Delegated to: Netdev Maintainers
Headers show
Series dccp: don't duplicate ccid when cloning dccp sock | expand

Checks

Context Check Description
netdev/tree_selection success Guessing tree name failed - patch did not apply

Commit Message

Lin, Zhenpeng Sept. 7, 2021, 6:28 p.m. UTC 
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@psu.edu>
---
net/dccp/minisocks.c | 2 ++
1 file changed, 2 insertions(+)

--
2.25.1
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Patch

diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index c5c74a34d139..91e7a2202697 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -94,6 +94,8 @@  struct sock *dccp_create_openreq_child(const struct sock *sk,
		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;