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tcp: avoid possible arithmetic overflows

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icsk_rto is a 32bit field, and icsk_backoff can reach 15 by default,
or more if some sysctl (eg tcp_retries2) are changed.

Better use 64bit to perform icsk_rto << icsk_backoff operations

As Joe Perches suggested, add a helper for this.

Yuchung spotted the tcp_v4_err() case.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2014-09-22 13:19:44 -07:00 committed by David S. Miller
parent 35f7aa5309
commit fcdd1cf4dd
5 changed files with 23 additions and 14 deletions
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9
include/net/inet_connection_sock.h
View File

@ -242,6 +242,15 @@ static inline void inet_csk_reset_xmit_timer(struct sock *sk, const int what,
#endif
}
static inline unsigned long
inet_csk_rto_backoff(const struct inet_connection_sock *icsk,
unsigned long max_when)
{
u64 when = (u64)icsk->icsk_rto << icsk->icsk_backoff;
return (unsigned long)min_t(u64, when, max_when);
}
struct sock *inet_csk_accept(struct sock *sk, int flags, int *err);
struct request_sock *inet_csk_search_req(const struct sock *sk,

5
net/ipv4/tcp_input.c
View File

@ -3208,9 +3208,10 @@ static void tcp_ack_probe(struct sock *sk)
* This function is not for random using!
*/
} else {
unsigned long when = inet_csk_rto_backoff(icsk, TCP_RTO_MAX);
inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX),
TCP_RTO_MAX);
when, TCP_RTO_MAX);
}
}

6
net/ipv4/tcp_ipv4.c
View File

@ -430,9 +430,9 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info)
break;
icsk->icsk_backoff--;
inet_csk(sk)->icsk_rto = (tp->srtt_us ? __tcp_set_rto(tp) :
TCP_TIMEOUT_INIT) << icsk->icsk_backoff;
tcp_bound_rto(sk);
icsk->icsk_rto = tp->srtt_us ? __tcp_set_rto(tp) :
TCP_TIMEOUT_INIT;
icsk->icsk_rto = inet_csk_rto_backoff(icsk, TCP_RTO_MAX);
skb = tcp_write_queue_head(sk);
BUG_ON(!skb);

13
net/ipv4/tcp_output.c
View File

@ -3279,6 +3279,7 @@ void tcp_send_probe0(struct sock *sk)
{
struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
unsigned long probe_max;
int err;
err = tcp_write_wakeup(sk);
@ -3294,9 +3295,7 @@ void tcp_send_probe0(struct sock *sk)
if (icsk->icsk_backoff < sysctl_tcp_retries2)
icsk->icsk_backoff++;
icsk->icsk_probes_out++;
inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
min(icsk->icsk_rto << icsk->icsk_backoff, TCP_RTO_MAX),
TCP_RTO_MAX);
probe_max = TCP_RTO_MAX;
} else {
/* If packet was not sent due to local congestion,
* do not backoff and do not remember icsk_probes_out.
@ -3306,11 +3305,11 @@ void tcp_send_probe0(struct sock *sk)
*/
if (!icsk->icsk_probes_out)
icsk->icsk_probes_out = 1;
inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
min(icsk->icsk_rto << icsk->icsk_backoff,
TCP_RESOURCE_PROBE_INTERVAL),
TCP_RTO_MAX);
probe_max = TCP_RESOURCE_PROBE_INTERVAL;
}
inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
inet_csk_rto_backoff(icsk, probe_max),
TCP_RTO_MAX);
}
int tcp_rtx_synack(struct sock *sk, struct request_sock *req)

4
net/ipv4/tcp_timer.c
View File

@ -180,7 +180,7 @@ static int tcp_write_timeout(struct sock *sk)
retry_until = sysctl_tcp_retries2;
if (sock_flag(sk, SOCK_DEAD)) {
const int alive = (icsk->icsk_rto < TCP_RTO_MAX);
const int alive = icsk->icsk_rto < TCP_RTO_MAX;
retry_until = tcp_orphan_retries(sk, alive);
do_reset = alive ||
@ -294,7 +294,7 @@ static void tcp_probe_timer(struct sock *sk)
max_probes = sysctl_tcp_retries2;
if (sock_flag(sk, SOCK_DEAD)) {
const int alive = ((icsk->icsk_rto << icsk->icsk_backoff) < TCP_RTO_MAX);
const int alive = inet_csk_rto_backoff(icsk, TCP_RTO_MAX) < TCP_RTO_MAX;
max_probes = tcp_orphan_retries(sk, alive);