3.2.52-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Roman Gushchin <klamm@xxxxxxxxxxxxxx>
[ Upstream commit 5f671d6b4ec3e6d66c2a868738af2cdea09e7509 ]
It's possible to assign an invalid value to the net.core.somaxconn
sysctl variable, because there is no checks at all.
The sk_max_ack_backlog field of the sock structure is defined as
unsigned short. Therefore, the backlog argument in inet_listen()
shouldn't exceed USHRT_MAX. The backlog argument in the listen() syscall
is truncated to the somaxconn value. So, the somaxconn value shouldn't
exceed 65535 (USHRT_MAX).
Also, negative values of somaxconn are meaningless.
before:
$ sysctl -w net.core.somaxconn=256
net.core.somaxconn = 256
$ sysctl -w net.core.somaxconn=65536
net.core.somaxconn = 65536
$ sysctl -w net.core.somaxconn=-100
net.core.somaxconn = -100
after:
$ sysctl -w net.core.somaxconn=256
net.core.somaxconn = 256
$ sysctl -w net.core.somaxconn=65536
error: "Invalid argument" setting key "net.core.somaxconn"
$ sysctl -w net.core.somaxconn=-100
error: "Invalid argument" setting key "net.core.somaxconn"
Based on a prior patch from Changli Gao.
Signed-off-by: Roman Gushchin <klamm@xxxxxxxxxxxxxx>
Reported-by: Changli Gao <xiaosuo@xxxxxxxxx>
Suggested-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
net/core/sysctl_net_core.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/net/core/sysctl_net_core.c b/net/core/sysctl_net_core.c
index 77a65f0..f0bdd36 100644
--- a/net/core/sysctl_net_core.c
+++ b/net/core/sysctl_net_core.c
@@ -19,6 +19,9 @@
#include <net/sock.h>
#include <net/net_ratelimit.h>
+static int zero = 0;
+static int ushort_max = USHRT_MAX;
+
#ifdef CONFIG_RPS
static int rps_sock_flow_sysctl(ctl_table *table, int write,
void __user *buffer, size_t *lenp, loff_t *ppos)
@@ -192,7 +195,9 @@ static struct ctl_table netns_core_table[] = {
.data = &init_net.core.sysctl_somaxconn,
.maxlen = sizeof(int),
.mode = 0644,
- .proc_handler = proc_dointvec
+ .extra1 = &zero,
+ .extra2 = &ushort_max,
+ .proc_handler = proc_dointvec_minmax
},
{ }
};
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