netdev - Re: [PATCH net-next] net: tipc: avoid possible garbage value

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Message-ID: <20240914094244.GG12935@kernel.org>
Date: Sat, 14 Sep 2024 10:42:44 +0100
From: Simon Horman <horms@...nel.org>
To: Su Hui <suhui@...china.com>
Cc: jmaloy@...hat.com, ying.xue@...driver.com, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	nathan@...nel.org, ndesaulniers@...gle.com, morbo@...gle.com,
	justinstitt@...gle.com, tuong.t.lien@...tech.com.au,
	netdev@...r.kernel.org, tipc-discussion@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org, llvm@...ts.linux.dev,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH net-next] net: tipc: avoid possible garbage value

On Thu, Sep 12, 2024 at 07:01:20PM +0800, Su Hui wrote:
> Clang static checker (scan-build) warning:
> net/tipc/bcast.c:305:4:
> The expression is an uninitialized value. The computed value will also
> be garbage [core.uninitialized.Assign]
>   305 |                         (*cong_link_cnt)++;
>       |                         ^~~~~~~~~~~~~~~~~~
> 
> tipc_rcast_xmit() will increase cong_link_cnt's value, but cong_link_cnt
> is uninitialized. Although it won't really cause a problem, it's better
> to fix it.
> 
> Fixes: dca4a17d24ee ("tipc: fix potential hanging after b/rcast changing")
> Signed-off-by: Su Hui <suhui@...china.com>

Hi Su Hui,

This looks like a bug fix. If so it should be targeted at net rather than
net-next. If not, the Fixes tag should be dropped, and the commit can be
referenced in the patch description with some other text around:

commit dca4a17d24ee ("tipc: fix potential hanging after b/rcast changing")

> ---
>  net/tipc/bcast.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/tipc/bcast.c b/net/tipc/bcast.c
> index 593846d25214..a3699be6a634 100644
> --- a/net/tipc/bcast.c
> +++ b/net/tipc/bcast.c
> @@ -321,7 +321,7 @@ static int tipc_mcast_send_sync(struct net *net, struct sk_buff *skb,
>  	struct tipc_msg *hdr, *_hdr;
>  	struct sk_buff_head tmpq;
>  	struct sk_buff *_skb;
> -	u16 cong_link_cnt;
> +	u16 cong_link_cnt = 0;
>  	int rc = 0;

I think we should preserve reverse xmas tree order - longest like to
shortest - for these local variable declarations.

>  
>  	/* Is a cluster supporting with new capabilities ? */
> -- 
> 2.30.2
> 
>