From b506bc975f60f06e13e74adb35e708a23dc4e87c Mon Sep 17 00:00:00 2001
From: Dust Li <dust.li@linux.alibaba.com>
Date: Mon, 1 Apr 2019 16:04:53 +0800
Subject: [PATCH] tcp: fix a potential NULL pointer dereference in tcp_sk_exit
When tcp_sk_init() failed in inet_ctl_sock_create(),
'net->ipv4.tcp_congestion_control' will be left
uninitialized, but tcp_sk_exit() hasn't check for
that.
This patch add checking on 'net->ipv4.tcp_congestion_control'
in tcp_sk_exit() to prevent NULL-ptr dereference.
Fixes: 6670e1524477 ("tcp: Namespace-ify sysctl_tcp_default_congestion_control")
Signed-off-by: Dust Li <dust.li@linux.alibaba.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
net/ipv4/tcp_ipv4.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 277d71239d755..2f8039a26b08f 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2578,7 +2578,8 @@ static void __net_exit tcp_sk_exit(struct net *net)
{
int cpu;
- module_put(net->ipv4.tcp_congestion_control->owner);
+ if (net->ipv4.tcp_congestion_control)
+ module_put(net->ipv4.tcp_congestion_control->owner);
for_each_possible_cpu(cpu)
inet_ctl_sock_destroy(*per_cpu_ptr(net->ipv4.tcp_sk, cpu));
--
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