ip: Fix data-races around sysctl_ip_default_ttl.

While reading sysctl_ip_default_ttl, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/ethernet/netronome/nfp/flower/action.c b/drivers/net/ethernet/netronome/nfp/flower/action.c
index 0147de4..ffb6f6d 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/flower/action.c
+++ b/drivers/net/ethernet/netronome/nfp/flower/action.c
@@ -474,7 +474,7 @@ nfp_fl_set_tun(struct nfp_app *app, struct nfp_fl_set_tun *set_tun,
                        set_tun->ttl = ip4_dst_hoplimit(&rt->dst);
                        ip_rt_put(rt);
                } else {
-                       set_tun->ttl = net->ipv4.sysctl_ip_default_ttl;
+                       set_tun->ttl = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
                }
        }
 

diff --git a/include/net/route.h b/include/net/route.h
index 991a398..bbcf2ab 100644 (file)
--- a/include/net/route.h
+++ b/include/net/route.h
@@ -373,7 +373,7 @@ static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
        struct net *net = dev_net(dst->dev);
 
        if (hoplimit == 0)
-               hoplimit = net->ipv4.sysctl_ip_default_ttl;
+               hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
        return hoplimit;
 }
 

diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index 445a9ec..d497d52 100644 (file)
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -1606,7 +1606,7 @@ static int do_ip_getsockopt(struct sock *sk, int level, int optname,
        {
                struct net *net = sock_net(sk);
                val = (inet->uc_ttl == -1 ?
-                      net->ipv4.sysctl_ip_default_ttl :
+                      READ_ONCE(net->ipv4.sysctl_ip_default_ttl) :
                       inet->uc_ttl);
                break;
        }

diff --git a/net/ipv4/netfilter/nf_reject_ipv4.c b/net/ipv4/netfilter/nf_reject_ipv4.c
index 918c61f..d640adc 100644 (file)
--- a/net/ipv4/netfilter/nf_reject_ipv4.c
+++ b/net/ipv4/netfilter/nf_reject_ipv4.c
@@ -62,7 +62,7 @@ struct sk_buff *nf_reject_skb_v4_tcp_reset(struct net *net,
 
        skb_reserve(nskb, LL_MAX_HEADER);
        niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_TCP,
-                                  net->ipv4.sysctl_ip_default_ttl);
+                                  READ_ONCE(net->ipv4.sysctl_ip_default_ttl));
        nf_reject_ip_tcphdr_put(nskb, oldskb, oth);
        niph->tot_len = htons(nskb->len);
        ip_send_check(niph);
@@ -117,7 +117,7 @@ struct sk_buff *nf_reject_skb_v4_unreach(struct net *net,
 
        skb_reserve(nskb, LL_MAX_HEADER);
        niph = nf_reject_iphdr_put(nskb, oldskb, IPPROTO_ICMP,
-                                  net->ipv4.sysctl_ip_default_ttl);
+                                  READ_ONCE(net->ipv4.sysctl_ip_default_ttl));
 
        skb_reset_transport_header(nskb);
        icmph = skb_put_zero(nskb, sizeof(struct icmphdr));

diff --git a/net/ipv4/proc.c b/net/ipv4/proc.c
index 2883607..0088a4c 100644 (file)
--- a/net/ipv4/proc.c
+++ b/net/ipv4/proc.c
@@ -387,7 +387,7 @@ static int snmp_seq_show_ipstats(struct seq_file *seq, void *v)
 
        seq_printf(seq, "\nIp: %d %d",
                   IPV4_DEVCONF_ALL(net, FORWARDING) ? 1 : 2,
-                  net->ipv4.sysctl_ip_default_ttl);
+                  READ_ONCE(net->ipv4.sysctl_ip_default_ttl));
 
        BUILD_BUG_ON(offsetof(struct ipstats_mib, mibs) != 0);
        snmp_get_cpu_field64_batch(buff64, snmp4_ipstats_list,

diff --git a/net/netfilter/nf_synproxy_core.c b/net/netfilter/nf_synproxy_core.c
index e479dd0..16915f8 100644 (file)
--- a/net/netfilter/nf_synproxy_core.c
+++ b/net/netfilter/nf_synproxy_core.c
@@ -405,7 +405,7 @@ synproxy_build_ip(struct net *net, struct sk_buff *skb, __be32 saddr,
        iph->tos        = 0;
        iph->id         = 0;
        iph->frag_off   = htons(IP_DF);
-       iph->ttl        = net->ipv4.sysctl_ip_default_ttl;
+       iph->ttl        = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
        iph->protocol   = IPPROTO_TCP;
        iph->check      = 0;
        iph->saddr      = saddr;