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tcp: avoid integer overflows in tcp_rcv_space_adjust()

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When using large tcp_rmem[2] values (I did tests with 500 MB),
I noticed overflows while computing rcvwin.

Lets fix this before the following patch.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Soheil Hassas Yeganeh <soheil@google.com>
Acked-by: Wei Wang <weiwan@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2017-12-10 17:55:03 -08:00 committed by David S. Miller
parent 02db55718d
commit 607065bad9
2 changed files with 8 additions and 6 deletions
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2
include/linux/tcp.h
View File

@ -344,7 +344,7 @@ struct tcp_sock {
/* Receiver queue space */
struct {
int space;
u32 space;
u32 seq;
u64 time;
} rcvq_space;

12
net/ipv4/tcp_input.c
View File

@ -576,8 +576,8 @@ static inline void tcp_rcv_rtt_measure_ts(struct sock *sk,
void tcp_rcv_space_adjust(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
u32 copied;
int time;
int copied;
tcp_mstamp_refresh(tp);
time = tcp_stamp_us_delta(tp->tcp_mstamp, tp->rcvq_space.time);
@ -600,12 +600,13 @@ void tcp_rcv_space_adjust(struct sock *sk)
if (sock_net(sk)->ipv4.sysctl_tcp_moderate_rcvbuf &&
!(sk->sk_userlocks & SOCK_RCVBUF_LOCK)) {
int rcvwin, rcvmem, rcvbuf;
int rcvmem, rcvbuf;
u64 rcvwin;
/* minimal window to cope with packet losses, assuming
* steady state. Add some cushion because of small variations.
*/
rcvwin = (copied << 1) + 16 * tp->advmss;
rcvwin = ((u64)copied << 1) + 16 * tp->advmss;
/* If rate increased by 25%,
* assume slow start, rcvwin = 3 * copied
@ -625,8 +626,9 @@ void tcp_rcv_space_adjust(struct sock *sk)
while (tcp_win_from_space(sk, rcvmem) < tp->advmss)
rcvmem += 128;
rcvbuf = min(rcvwin / tp->advmss * rcvmem,
sock_net(sk)->ipv4.sysctl_tcp_rmem[2]);
do_div(rcvwin, tp->advmss);
rcvbuf = min_t(u64, rcvwin * rcvmem,
sock_net(sk)->ipv4.sysctl_tcp_rmem[2]);
if (rcvbuf > sk->sk_rcvbuf) {
sk->sk_rcvbuf = rcvbuf;