2 files changed, 6 insertions, 1 deletions

diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index fe95105992c5..3c5e465296e1 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -144,6 +144,7 @@ tcp_adv_win_scale - INTEGER
         Count buffering overhead as bytes/2^tcp_adv_win_scale
         (if tcp_adv_win_scale > 0) or bytes-bytes/2^(-tcp_adv_win_scale),
         if it is <= 0.
+        Possible values are [-31, 31], inclusive.
         Default: 2
 
 tcp_allowed_congestion_control - STRING
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index e91911d7aae2..1b4ec21497a4 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -26,6 +26,8 @@ static int zero;
 static int tcp_retr1_max = 255;
 static int ip_local_port_range_min[] = { 1, 1 };
 static int ip_local_port_range_max[] = { 65535, 65535 };
+static int tcp_adv_win_scale_min = -31;
+static int tcp_adv_win_scale_max = 31;
 
 /* Update system visible IP port range */
 static void set_local_port_range(int range[2])
@@ -426,7 +428,9 @@ static struct ctl_table ipv4_table[] = {
                 .data           = &sysctl_tcp_adv_win_scale,
                 .maxlen         = sizeof(int),
                 .mode           = 0644,
-                .proc_handler   = proc_dointvec
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = &tcp_adv_win_scale_min,
+                .extra2         = &tcp_adv_win_scale_max,
         },
         {
                 .procname       = "tcp_tw_reuse",