netdev - Re: v3 for tcp friends?

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Message-ID: <1358923606.12374.746.camel@edumazet-glaptop>
Date:	Tue, 22 Jan 2013 22:46:46 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Li Yu <raise.sail@...il.com>
Cc:	Bruce Curtis <brutus@...gle.com>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>
Subject: Re: v3 for tcp friends?

On Wed, 2013-01-23 at 14:12 +0800, Li Yu wrote:
> Oops, this hang is not since TCP friends patch!
> 
> sk_sndbuf_get() is broken by 32 bits integer overflow
> because of so large value in net.ipv4.tcp_{rmem,wmem}.
> 
> but this hang also can be found in net-next.git
> (3.8.0-rc3+), if we run below commands, then all new
> TCP connections stop working!
> 
> # when TCP friends is disabled
> sysctl -w net.ipv4.tcp_rmem="4096 4294967296 4294967296" # 4GB
> sysctl -w net.ipv4.tcp_wmem="4096 4294967296 4294967296"

Right we need to make sure we dont overflow.

Try the following fix :

diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index a25e1d2..1459145 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -549,14 +549,16 @@ static struct ctl_table ipv4_table[] = {
 		.data		= &sysctl_tcp_wmem,
 		.maxlen		= sizeof(sysctl_tcp_wmem),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.extra1		= &zero,
+		.proc_handler	= proc_dointvec_minmax
 	},
 	{
 		.procname	= "tcp_rmem",
 		.data		= &sysctl_tcp_rmem,
 		.maxlen		= sizeof(sysctl_tcp_rmem),
 		.mode		= 0644,
-		.proc_handler	= proc_dointvec
+		.extra1		= &zero,
+		.proc_handler	= proc_dointvec_minmax
 	},
 	{
 		.procname	= "tcp_app_win",


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