linux-kernel - [PATCH 4.9 17/28] net: diag: Dont double-free TCP_NEW_SYN_RECV sockets in tcp

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Date:   Mon, 23 Jul 2018 14:25:17 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Ahern <dsa@...ulusnetworks.com>,
        Lorenzo Colitti <lorenzo@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 17/28] net: diag: Dont double-free TCP_NEW_SYN_RECV sockets in tcp_abort

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Lorenzo Colitti <lorenzo@...gle.com>

[ Upstream commit acc2cf4e37174646a24cba42fa53c668b2338d4e ]

When tcp_diag_destroy closes a TCP_NEW_SYN_RECV socket, it first
frees it by calling inet_csk_reqsk_queue_drop_and_and_put in
tcp_abort, and then frees it again by calling sock_gen_put.

Since tcp_abort only has one caller, and all the other codepaths
in tcp_abort don't free the socket, just remove the free in that
function.

Cc: David Ahern <dsa@...ulusnetworks.com>
Tested: passes Android sock_diag_test.py, which exercises this codepath
Fixes: d7226c7a4dd1 ("net: diag: Fix refcnt leak in error path destroying socket")
Signed-off-by: Lorenzo Colitti <lorenzo@...gle.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reviewed-by: David Ahern <dsa@...ulusnetworks.com>
Tested-by: David Ahern <dsa@...ulusnetworks.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/tcp.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -3238,8 +3238,7 @@ int tcp_abort(struct sock *sk, int err)
 			struct request_sock *req = inet_reqsk(sk);
 
 			local_bh_disable();
-			inet_csk_reqsk_queue_drop_and_put(req->rsk_listener,
-							  req);
+			inet_csk_reqsk_queue_drop(req->rsk_listener, req);
 			local_bh_enable();
 			return 0;
 		}