Commit 60c158dc authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by David S. Miller

ip: Fix data-races around sysctl_ip_fwd_use_pmtu.

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

Fixes: f87c10a8 ("ipv4: introduce ip_dst_mtu_maybe_forward and protect forwarding path against pmtu spoofing")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0968d2a4
...@@ -446,7 +446,7 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst, ...@@ -446,7 +446,7 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
struct net *net = dev_net(dst->dev); struct net *net = dev_net(dst->dev);
unsigned int mtu; unsigned int mtu;
if (net->ipv4.sysctl_ip_fwd_use_pmtu || if (READ_ONCE(net->ipv4.sysctl_ip_fwd_use_pmtu) ||
ip_mtu_locked(dst) || ip_mtu_locked(dst) ||
!forwarding) { !forwarding) {
mtu = rt->rt_pmtu; mtu = rt->rt_pmtu;
......
...@@ -1398,7 +1398,7 @@ u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr) ...@@ -1398,7 +1398,7 @@ u32 ip_mtu_from_fib_result(struct fib_result *res, __be32 daddr)
struct fib_info *fi = res->fi; struct fib_info *fi = res->fi;
u32 mtu = 0; u32 mtu = 0;
if (dev_net(dev)->ipv4.sysctl_ip_fwd_use_pmtu || if (READ_ONCE(dev_net(dev)->ipv4.sysctl_ip_fwd_use_pmtu) ||
fi->fib_metrics->metrics[RTAX_LOCK - 1] & (1 << RTAX_MTU)) fi->fib_metrics->metrics[RTAX_LOCK - 1] & (1 << RTAX_MTU))
mtu = fi->fib_mtu; mtu = fi->fib_mtu;
......
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