dccp: don't duplicate ccid when cloning dccp sock

Commit 2677d20 ("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: 2677d20 ("dccp: don't free ccid2_hc_tx_sock ...") Signed-off-by: Zhenpeng Lin <[email protected]> Signed-off-by: David S. Miller <[email protected]>
niw · Sep 8, 2021 · d9ea761 · d9ea761
1 parent 0f31ab2
commit d9ea761
Showing 1 changed file with 2 additions and 0 deletions.
diff --git 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;