netdev - Re: [PATCH net 3/3] sched: cls_flow: fix panic on filter replace

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Date:	Fri, 17 Jul 2015 14:07:33 -0700
From:	John Fastabend <john.fastabend@...il.com>
To:	Daniel Borkmann <daniel@...earbox.net>, davem@...emloft.net
CC:	ast@...mgrid.com, jiri@...nulli.us, jhs@...atatu.com,
	edumazet@...gle.com, netdev@...r.kernel.org
Subject: Re: [PATCH net 3/3] sched: cls_flow: fix panic on filter replace

On 15-07-17 01:38 PM, Daniel Borkmann wrote:
> The following test case causes a NULL pointer dereference in cls_flow:
> 
>   tc filter add dev foo parent 1: handle 0x1 flow hash keys dst action ok
>   tc filter replace dev foo parent 1: pref 49152 handle 0x1 \
>             flow hash keys mark action drop
> 
> To be more precise, actually two different panics are fixed, the first
> occurs because tcf_exts_init() is not called on the newly allocated
> filter when we do a replace. And the second panic uncovered after that
> happens since the arguments of list_replace_rcu() are swapped, the old
> element needs to be the first argument and the new element the second.
> 
> Fixes: 70da9f0bf999 ("net: sched: cls_flow use RCU")
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> ---
>  net/sched/cls_flow.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 

Thanks again, I must have missed running replace tests in these cases.

Acked-by: John Fastabend <john.r.fastabend@...el.com>

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