-------- Original Message -------- Subject: Re: [PATCH] net: check net.core.somaxconn sysctl values Date: Wed, 31 Jul 2013 07:37:37 -0700 From: Eric Dumazet <[email protected]> To: Roman Gushchin <[email protected]> CC: David S. Miller <[email protected]>, [email protected], [email protected], [email protected], [email protected] 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 <[email protected]> --- 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 ;) Based on a prior patch from Changli Gao Reported-by: Changli Gao <[email protected]> Suggested-by: Eric Dumazet <[email protected]> Acked-by: Eric Dumazet <[email protected]> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
