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SubjectRe: [PATCH] net: check net.core.somaxconn sysctl values
On 31.07.2013 18:37, Eric Dumazet wrote:
> On Wed, 2013-07-31 at 17:57 +0400, Roman Gushchin wrote:
>> 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"
>>
>> Signed-off-by: Roman Gushchin <klamm@yandex-team.ru>
>> ---
>> net/core/sysctl_net_core.c | 6 +++++-
>> 1 file changed, 5 insertions(+), 1 deletion(-)
>
>
> We had a discussion about this one month ago, as Changli Gao posted a
> patch. http://patchwork.ozlabs.org/patch/255460/
>
> So proper credits would be nice ;)

Ok :)

> Based on a prior patch from Changli Gao
>
> Reported-by: Changli Gao <xiaosuo@gmail.com>
> Suggested-by: Eric Dumazet <edumazet@google.com>
>
> Acked-by: Eric Dumazet <edumazet@google.com>
>

Thanks!

PS I've forwarded your letter back to the lkml by mistake.
Sorry)

Regards,
Roman



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