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authorKuniyuki Iwashima <kuniyu@amazon.com>2022-07-13 13:52:01 -0700
committerDavid S. Miller <davem@davemloft.net>2022-07-15 11:49:55 +0100
commit88d78bc097cd8ebc6541e93316c9d9bf651b13e8 (patch)
treec76a6a482e4b6238c272aac7170c9b99491f3629
parenttcp: Fix data-races around sysctl_tcp_mtu_probing. (diff)
downloadlinux-dev-88d78bc097cd8ebc6541e93316c9d9bf651b13e8.tar.xz
linux-dev-88d78bc097cd8ebc6541e93316c9d9bf651b13e8.zip
tcp: Fix data-races around sysctl_tcp_base_mss.
While reading sysctl_tcp_base_mss, it can be changed concurrently. Thus, we need to add READ_ONCE() to its readers. Fixes: 5d424d5a674f ("[TCP]: MTU probing") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/ipv4/tcp_output.c2
-rw-r--r--net/ipv4/tcp_timer.c2
2 files changed, 2 insertions, 2 deletions
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 3fcfc0f1e9f9..9450d8469871 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -1765,7 +1765,7 @@ void tcp_mtup_init(struct sock *sk)
icsk->icsk_mtup.enabled = READ_ONCE(net->ipv4.sysctl_tcp_mtu_probing) > 1;
icsk->icsk_mtup.search_high = tp->rx_opt.mss_clamp + sizeof(struct tcphdr) +
icsk->icsk_af_ops->net_header_len;
- icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, net->ipv4.sysctl_tcp_base_mss);
+ icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, READ_ONCE(net->ipv4.sysctl_tcp_base_mss));
icsk->icsk_mtup.probe_size = 0;
if (icsk->icsk_mtup.enabled)
icsk->icsk_mtup.probe_timestamp = tcp_jiffies32;
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index 98bb00e29e1e..04063c7e33ba 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -171,7 +171,7 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk)
icsk->icsk_mtup.probe_timestamp = tcp_jiffies32;
} else {
mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1;
- mss = min(net->ipv4.sysctl_tcp_base_mss, mss);
+ mss = min(READ_ONCE(net->ipv4.sysctl_tcp_base_mss), mss);
mss = max(mss, net->ipv4.sysctl_tcp_mtu_probe_floor);
mss = max(mss, net->ipv4.sysctl_tcp_min_snd_mss);
icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss);