netdev - Re: [PATCH net] net:sysctl fix the confusing corner of tcp

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 09 Dec 2015 10:38:01 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Wang Yufen <wangyufen@...wei.com>
Cc:	<davem@...emloft.net>, <netdev@...r.kernel.org>,
	<guohanjun@...wei.com>, <zhangdianfang@...wei.com>,
	<dingtianhong@...wei.com>, <huxinwei@...wei.com>,
	Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: [PATCH net] net:sysctl fix the confusing corner of tcp_mem

Wang Yufen <wangyufen@...wei.com> writes:

> From: Yufen Wang <wangyufen@...wei.com>
>
> I tried on linux-4.1:
>     linux:~# cat /proc/sys/net/ipv4/tcp_mem 
>     8388608	12582912	16777216
>     linux:~# echo 1234 >/proc/sys/net/ipv4/tcp_mem 
>     -bash: echo: write error: Invalid argument
>     linux:~# cat /proc/sys/net/ipv4/tcp_mem 
>     1234	12582912	16777216
>
> the echo operation got error, but value already written to tcp_mem.
> If a write() returns an error like EINVAL, we expect no change occurred.
> This patch fix the confusing corner and makes __do_proc_doulongvec_minmax 
> works the same as __do_proc_dointvec

Nacked-by: "Eric W. Biederman" <ebiederm@...ssion.com>

Except for possibly breaking your muscle memory this does not explain
why this is a problem.

Further you are changing a whole lot more than tcp_mem, without a word
of justification in your description.

I do not think changing every integer use of sysctl for some unknown
reason.  Is justified in this case.

Eric



> Signed-off-by: Yufen Wang <wangyufen@...wei.com>
> Cc: Eric Dumazet <eric.dumazet@...il.com>
> Cc: "Eric W. Biederman" <ebiederm@...ssion.com>
> ---
>  kernel/sysctl.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index c3eee4c..e3ee4be 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -2318,6 +2318,8 @@ static int __do_proc_doulongvec_minmax(void *data, struct ctl_table *table, int
>  			bool neg;
>  
>  			left -= proc_skip_spaces(&kbuf);
> +                        if (!left)
> +                                break;
>  
>  			err = proc_get_long(&kbuf, &left, &val, &neg,
>  					     proc_wspace_sep,
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html