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SubjectRe: [PATCH net] ipv6: fix panic when forwarding a pkt with no in6 dev
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On 4/8/22 07:03, Nicolas Dichtel wrote:
> kongweibin reported a kernel panic in ip6_forward() when input interface
> has no in6 dev associated.
>
> The following tc commands were used to reproduce this panic:
> tc qdisc del dev vxlan100 root
> tc qdisc add dev vxlan100 root netem corrupt 5%

Not sure I understand how these qdisc changes can trigger a NULL idev ?

Do we have another bug, like skb->cb[] content being mangled ?


>
> CC: stable@vger.kernel.org
> Fixes: ccd27f05ae7b ("ipv6: fix 'disable_policy' for fwd packets")
> Reported-by: kongweibin <kongweibin2@huawei.com>
> Signed-off-by: Nicolas Dichtel <nicolas.dichtel@6wind.com>
> ---
>
> kongweibin, could you test this patch with your setup?
>
> Thanks,
> Nicolas
>
> net/ipv6/ip6_output.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
> index e23f058166af..fa63ef2bd99c 100644
> --- a/net/ipv6/ip6_output.c
> +++ b/net/ipv6/ip6_output.c
> @@ -485,7 +485,7 @@ int ip6_forward(struct sk_buff *skb)
> goto drop;
>
> if (!net->ipv6.devconf_all->disable_policy &&
> - !idev->cnf.disable_policy &&
> + (!idev || !idev->cnf.disable_policy) &&
> !xfrm6_policy_check(NULL, XFRM_POLICY_FWD, skb)) {
> __IP6_INC_STATS(net, idev, IPSTATS_MIB_INDISCARDS);
> goto drop;

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