From: Eric Dumazet edumazet@google.com

commit 607065bad9931e72207b0cac365d7d4abc06bd99 upstream.

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 [Backport: sysctl_tcp_rmem is not Namespace-ify'd in older kernels] Signed-off-by: Guenter Roeck linux@roeck-us.net --- Applies cleanly to v4.4.y and v4.9.y; v4.14.y needs "git am -3".

include/linux/tcp.h | 2 +- net/ipv4/tcp_input.c | 10 ++++++---- 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 2260f92f1492..5b6df1a8dc74 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -324,7 +324,7 @@ struct tcp_sock {

/* Receiver queue space */ struct { - int space; + u32 space; u32 seq; u32 time; } rcvq_space; diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index ed018760502e..23b95aead897 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -557,8 +557,8 @@ 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;

time = tcp_time_stamp - tp->rcvq_space.time; if (time < (tp->rcv_rtt_est.rtt >> 3) || tp->rcv_rtt_est.rtt == 0) @@ -580,12 +580,13 @@ void tcp_rcv_space_adjust(struct sock *sk)

if (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 @@ -605,7 +606,8 @@ void tcp_rcv_space_adjust(struct sock *sk) while (tcp_win_from_space(rcvmem) < tp->advmss) rcvmem += 128;

- rcvbuf = min(rcvwin / tp->advmss * rcvmem, sysctl_tcp_rmem[2]); + do_div(rcvwin, tp->advmss); + rcvbuf = min_t(u64, rcvwin * rcvmem, sysctl_tcp_rmem[2]); if (rcvbuf > sk->sk_rcvbuf) { sk->sk_rcvbuf = rcvbuf;