[PATCH 3.4 092/107] net: avoid to hang up on sending due to sysctl configuration overflow.

From: lizf
Date: Wed Mar 16 2016 - 04:12:58 EST


From: "bingtian.ly@xxxxxxxxxx" <bingtian.ly@xxxxxxxxxx>

3.4.111-rc1 review patch. If anyone has any objections, please let me know.

------------------


commit cdda88912d62f9603d27433338a18be83ef23ac1 upstream.

I found if we write a larger than 4GB value to some sysctl
variables, the sending syscall will hang up forever, because these
variables are 32 bits, such large values make them overflow to 0 or
negative.

This patch try to fix overflow or prevent from zero value setup
of below sysctl variables:

net.core.wmem_default
net.core.rmem_default

net.core.rmem_max
net.core.wmem_max

net.ipv4.udp_rmem_min
net.ipv4.udp_wmem_min

net.ipv4.tcp_wmem
net.ipv4.tcp_rmem

Signed-off-by: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Signed-off-by: Li Yu <raise.sail@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
net/core/sysctl_net_core.c | 14 ++++++++++----
net/ipv4/sysctl_net_ipv4.c | 11 +++++++----
2 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 77d1550..c04dadd 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -22,6 +22,8 @@
static int zero = 0;
static int ushort_max = USHRT_MAX;

+static int one = 1;
+
#ifdef CONFIG_RPS
static int rps_sock_flow_sysctl(ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -94,28 +96,32 @@ static struct ctl_table net_core_table[] = {
.data = &sysctl_wmem_max,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
},
{
.procname = "rmem_max",
.data = &sysctl_rmem_max,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
},
{
.procname = "wmem_default",
.data = &sysctl_wmem_default,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
},
{
.procname = "rmem_default",
.data = &sysctl_rmem_default,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
},
{
.procname = "dev_weight",
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 086c973..009e36d 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -27,6 +27,7 @@
#include <net/tcp_memcontrol.h>

static int zero;
+static int one = 1;
static int tcp_retr1_max = 255;
static int ip_local_port_range_min[] = { 1, 1 };
static int ip_local_port_range_max[] = { 65535, 65535 };
@@ -486,14 +487,16 @@ static struct ctl_table ipv4_table[] = {
.data = &sysctl_tcp_wmem,
.maxlen = sizeof(sysctl_tcp_wmem),
.mode = 0644,
- .proc_handler = proc_dointvec
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
},
{
.procname = "tcp_rmem",
.data = &sysctl_tcp_rmem,
.maxlen = sizeof(sysctl_tcp_rmem),
.mode = 0644,
- .proc_handler = proc_dointvec
+ .proc_handler = proc_dointvec_minmax,
+ .extra1 = &one,
},
{
.procname = "tcp_app_win",
@@ -700,7 +703,7 @@ static struct ctl_table ipv4_table[] = {
.maxlen = sizeof(sysctl_udp_rmem_min),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
- .extra1 = &zero
+ .extra1 = &one
},
{
.procname = "udp_wmem_min",
@@ -708,7 +711,7 @@ static struct ctl_table ipv4_table[] = {
.maxlen = sizeof(sysctl_udp_wmem_min),
.mode = 0644,
.proc_handler = proc_dointvec_minmax,
- .extra1 = &zero
+ .extra1 = &one
},
{ }
};
--
1.9.1