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

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Message-ID: <f1279370-a127-4946-8c46-cc89fd2a90a6@stanley.mountain>
Date: Sat, 14 Sep 2024 13:05:29 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Simon Horman <horms@...nel.org>
Cc: Su Hui <suhui@...china.com>, 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 Sat, Sep 14, 2024 at 10:42:44AM +0100, Simon Horman wrote:
> 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:
> 


It's one of those borderline things.  As the commit message says it doesn't
really cause a problem because cong_link_cnt is never used.  I guess if you had
UBSan turned on it would generate a runtime warning.  Still it also doesn't seem
intentional so I would probably count it as a bugfix and target net like you
suggest.

regards,
dan carpenter