[PATCH Z/Y] dccp/tcp: do not inherit mc_list from parent
Stefan Bader
stefan.bader at canonical.com
Tue Jun 6 16:16:00 UTC 2017
From: Eric Dumazet <edumazet at google.com>
syzkaller found a way to trigger double frees from ip_mc_drop_socket()
It turns out that leave a copy of parent mc_list at accept() time,
which is very bad.
Very similar to commit 8b485ce69876 ("tcp: do not inherit
fastopen_req from parent")
Initial report from Pray3r, completed by Andrey one.
Thanks a lot to them !
Signed-off-by: Eric Dumazet <edumazet at google.com>
Reported-by: Pray3r <pray3r.z at gmail.com>
Reported-by: Andrey Konovalov <andreyknvl at google.com>
Tested-by: Andrey Konovalov <andreyknvl at google.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
CVE-2017-8890
(cherry-picked from 657831ffc38e30092a2d5f03d385d710eb88b09a)
Signed-off-by: Stefan Bader <stefan.bader at canonical.com>
---
net/ipv4/inet_connection_sock.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 19ea045..d952cfa 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -669,6 +669,8 @@ struct sock *inet_csk_clone_lock(const struct sock *sk,
/* listeners have SOCK_RCU_FREE, not the children */
sock_reset_flag(newsk, SOCK_RCU_FREE);
+ inet_sk(newsk)->mc_list = NULL;
+
newsk->sk_mark = inet_rsk(req)->ir_mark;
atomic64_set(&newsk->sk_cookie,
atomic64_read(&inet_rsk(req)->ir_cookie));
--
2.7.4
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