[PATCH 4.9 18/61] tcp: avoid integer overflows in tcp_rcv_space_adjust()
From: Greg Kroah-Hartman
Date: Tue Jun 05 2018 - 13:15:58 EST
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
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@xxxxxxxxxx>
Acked-by: Soheil Hassas Yeganeh <soheil@xxxxxxxxxx>
Acked-by: Wei Wang <weiwan@xxxxxxxxxx>
Acked-by: Neal Cardwell <ncardwell@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[Backport: sysctl_tcp_rmem is not Namespace-ify'd in older kernels]
Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/linux/tcp.h | 2 +-
net/ipv4/tcp_input.c | 10 ++++++----
2 files changed, 7 insertions(+), 5 deletions(-)
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -337,7 +337,7 @@ struct tcp_sock {
/* Receiver queue space */
struct {
- int space;
+ u32 space;
u32 seq;
u32 time;
} rcvq_space;
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -581,8 +581,8 @@ static inline void tcp_rcv_rtt_measure_t
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)
@@ -604,12 +604,13 @@ void tcp_rcv_space_adjust(struct sock *s
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
@@ -629,7 +630,8 @@ void tcp_rcv_space_adjust(struct sock *s
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;