Re: [PATCH 5.10 35/38] rtnetlink: Fix missing error code in rtnl_bridge_notify()

[Alexander Tsoy]

В Ср, 16/06/2021 в 17:33 +0200, Greg Kroah-Hartman пишет:
> From: Jiapeng Chong <jiapeng.chong@xxxxxxxxxxxxxxxxx>
> 
> [ Upstream commit a8db57c1d285c758adc7fb43d6e2bad2554106e1 ]
> 
> The error code is missing in this code scenario, add the error code
> '-EINVAL' to the return value 'err'.
> 
> Eliminate the follow smatch warning:
> 
> net/core/rtnetlink.c:4834 rtnl_bridge_notify() warn: missing error code
> 'err'.

This patch breaks systemd-resolved. It is 100% reproducible on two of
my systems, but there are also systems where I cannot reproduce it. The
problem manifests itself as SERVFAIL on every DNS query.

Just reverting this patch from 5.10.45 fixes the problem for me.

> 
> Reported-by: Abaci Robot <abaci@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Jiapeng Chong <jiapeng.chong@xxxxxxxxxxxxxxxxx>
> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
>  net/core/rtnetlink.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
> index eae8e87930cd..83894723ebee 100644
> --- a/net/core/rtnetlink.c
> +++ b/net/core/rtnetlink.c
> @@ -4842,8 +4842,10 @@ static int rtnl_bridge_notify(struct net_device
> *dev)
>         if (err < 0)
>                 goto errout;
>  
> -       if (!skb->len)
> +       if (!skb->len) {
> +               err = -EINVAL;
>                 goto errout;
> +       }
>  
>         rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_ATOMIC);
>         return 0;