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tcp: Fix data-races around some timeout sysctl knobs. 

While reading these sysctl knobs, they can be changed concurrently.
Thus, we need to add READ_ONCE() to their readers.

  - tcp_retries1
  - tcp_retries2
  - tcp_orphan_retries
  - tcp_fin_timeout

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Kuniyuki Iwashima 2022-07-15 10:17:50 -07:00 committed by David S. Miller
parent 46778cd16e
commit 39e24435a7
4 changed files with 9 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
include/net/tcp.h
View File

@ -1523,7 +1523,8 @@ static inline u32 keepalive_time_elapsed(const struct tcp_sock *tp)
static inline int tcp_fin_time(const struct sock *sk)
{
int fin_timeout = tcp_sk(sk)->linger2 ? : sock_net(sk)->ipv4.sysctl_tcp_fin_timeout;
int fin_timeout = tcp_sk(sk)->linger2 ? :
READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_fin_timeout);
const int rto = inet_csk(sk)->icsk_rto;
if (fin_timeout < (rto << 2) - (rto >> 1))

2
net/ipv4/tcp.c
View File

@ -3973,7 +3973,7 @@ static int do_tcp_getsockopt(struct sock *sk, int level,
case TCP_LINGER2:
val = tp->linger2;
if (val >= 0)
val = (val ? : net->ipv4.sysctl_tcp_fin_timeout) / HZ;
val = (val ? : READ_ONCE(net->ipv4.sysctl_tcp_fin_timeout)) / HZ;
break;
case TCP_DEFER_ACCEPT:
val = retrans_to_secs(icsk->icsk_accept_queue.rskq_defer_accept,

2
net/ipv4/tcp_output.c
View File

@ -4090,7 +4090,7 @@ void tcp_send_probe0(struct sock *sk)
icsk->icsk_probes_out++;
if (err <= 0) {
if (icsk->icsk_backoff < net->ipv4.sysctl_tcp_retries2)
if (icsk->icsk_backoff < READ_ONCE(net->ipv4.sysctl_tcp_retries2))
icsk->icsk_backoff++;
timeout = tcp_probe0_when(sk, TCP_RTO_MAX);
} else {

10
net/ipv4/tcp_timer.c
View File

@ -143,7 +143,7 @@ static int tcp_out_of_resources(struct sock *sk, bool do_reset)
*/
static int tcp_orphan_retries(struct sock *sk, bool alive)
{
int retries = sock_net(sk)->ipv4.sysctl_tcp_orphan_retries; /* May be zero. */
int retries = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_orphan_retries); /* May be zero. */
/* We know from an ICMP that something is wrong. */
if (sk->sk_err_soft && !alive)
@ -243,14 +243,14 @@ static int tcp_write_timeout(struct sock *sk)
READ_ONCE(net->ipv4.sysctl_tcp_syn_retries);
expired = icsk->icsk_retransmits >= retry_until;
} else {
if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1, 0)) {
if (retransmits_timed_out(sk, READ_ONCE(net->ipv4.sysctl_tcp_retries1), 0)) {
/* Black hole detection */
tcp_mtu_probing(icsk, sk);
__dst_negative_advice(sk);
}
retry_until = net->ipv4.sysctl_tcp_retries2;
retry_until = READ_ONCE(net->ipv4.sysctl_tcp_retries2);
if (sock_flag(sk, SOCK_DEAD)) {
const bool alive = icsk->icsk_rto < TCP_RTO_MAX;
@ -381,7 +381,7 @@ static void tcp_probe_timer(struct sock *sk)
msecs_to_jiffies(icsk->icsk_user_timeout))
goto abort;
max_probes = sock_net(sk)->ipv4.sysctl_tcp_retries2;
max_probes = READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_retries2);
if (sock_flag(sk, SOCK_DEAD)) {
const bool alive = inet_csk_rto_backoff(icsk, TCP_RTO_MAX) < TCP_RTO_MAX;
@ -589,7 +589,7 @@ out_reset_timer:
}
inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
tcp_clamp_rto_to_user_timeout(sk), TCP_RTO_MAX);
if (retransmits_timed_out(sk, net->ipv4.sysctl_tcp_retries1 + 1, 0))
if (retransmits_timed_out(sk, READ_ONCE(net->ipv4.sysctl_tcp_retries1) + 1, 0))
__sk_dst_reset(sk);
out:;