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Date: Sat, 20 Sep 2014 10:19:10 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: David Miller <davem@...emloft.net>
Cc: netdev <netdev@...r.kernel.org>,
Neal Cardwell <ncardwell@...gle.com>,
Yuchung Cheng <ycheng@...gle.com>
Subject: [PATCH net-next] tcp: avoid possible arithmetic overflows
From: Eric Dumazet <edumazet@...gle.com>
icsk_rto is an 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
From: Eric Dumazet <edumazet@...gle.com>
---
net/ipv4/tcp_input.c | 7 +++++--
net/ipv4/tcp_output.c | 13 ++++++-------
net/ipv4/tcp_timer.c | 5 +++--
3 files changed, 14 insertions(+), 11 deletions(-)
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index 02fb66d4a018..1ea3847c62fc 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -3208,9 +3208,12 @@ static void tcp_ack_probe(struct sock *sk)
* This function is not for random using!
*/
} else {
+ unsigned long when;
+
+ when = min((u64)icsk->icsk_rto << icsk->icsk_backoff,
+ (u64)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);
}
}
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 7f1280dcad57..2231b400f3ce 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -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 when;
int err;
err = tcp_write_wakeup(sk);
@@ -3294,9 +3295,8 @@ 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);
+ when = min((u64)icsk->icsk_rto << icsk->icsk_backoff,
+ (u64)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 +3306,10 @@ 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);
+ when = min((u64)icsk->icsk_rto << icsk->icsk_backoff,
+ (u64)TCP_RESOURCE_PROBE_INTERVAL);
}
+ inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0, when, TCP_RTO_MAX);
}
int tcp_rtx_synack(struct sock *sk, struct request_sock *req)
diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c
index a339e7ba05a4..05e1d0723233 100644
--- a/net/ipv4/tcp_timer.c
+++ b/net/ipv4/tcp_timer.c
@@ -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 +294,8 @@ 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);
+ u64 exp_rto = (u64)icsk->icsk_rto << icsk->icsk_backoff;
+ const int alive = exp_rto < TCP_RTO_MAX;
max_probes = tcp_orphan_retries(sk, alive);
--
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