Re: [dpdk-stable] [dpdk-dev] [PATCH v1] app/testpmd: fix DCB set failure in FreeBSD by clang

["Xu, Ting" <ting.xu@intel.com>]

> -----Original Message-----
> From: Yigit, Ferruh <ferruh.yigit@intel.com>
> Sent: Tuesday, May 12, 2020 12:29 AM
> To: Xu, Ting <ting.xu@intel.com>; dev@dpdk.org
> Cc: Lu, Wenzhuo <wenzhuo.lu@intel.com>; Xing, Beilei
> <beilei.xing@intel.com>; Iremonger, Bernard
> <bernard.iremonger@intel.com>; stable@dpdk.org; Andrew Rybchenko
> <arybchenko@solarflare.com>; Thomas Monjalon <thomas@monjalon.net>
> Subject: Re: [dpdk-dev] [PATCH v1] app/testpmd: fix DCB set failure in
> FreeBSD by clang
> 
> On 5/11/2020 11:25 AM, Ting Xu wrote:
> > When set DCB in testpmd by clang, there is a segmentation fault.
> > It is because the local variable rss_conf in get_eth_dcb_conf() is not
> > cleared, so that the pointer member variable rss_key has a random
> > address, which leads to an error in the following processing. This
> > patch initialized the local variable rss_conf to avoid random address.
> 
> This is nothing really FreeBSD or clang issue, although it may be reproduced
> that environment, this is a pointer with random value issue. We may drop
> FreeBSD and clang reference to not create confusion.
> 

OK,  I will modify the commit log.

> >
> > Fixes: b57b66a97ebf ("app/testpmd: support mbuf dynamic flag")
> 
> This commit looks unrelated, if not can you please explain why above
> commit causing the issue?
> 

This is the bad commit the validation team find for this issue. Honestly speaking,
I did not find the relation between this commit and the issue either.

> > Cc: stable@dpdk.org
> >
> > Signed-off-by: Ting Xu <ting.xu@intel.com>
> > ---
> >  app/test-pmd/testpmd.c | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/app/test-pmd/testpmd.c b/app/test-pmd/testpmd.c index
> > 99bacddbf..1276476ca 100644
> > --- a/app/test-pmd/testpmd.c
> > +++ b/app/test-pmd/testpmd.c
> > @@ -3408,6 +3408,7 @@ get_eth_dcb_conf(portid_t pid, struct
> rte_eth_conf *eth_conf,
> >  	int32_t rc;
> >  	struct rte_eth_rss_conf rss_conf;
> >
> > +	memset(&rss_conf, 0, sizeof(struct rte_eth_rss_conf));
> 
> The variable is used in the 'else' leg, memset can be moved there, but more
> importantly should this be done in the 'rte_eth_dev_rss_hash_conf_get()' API.
> 
> @Andrew, @Thomas,
> 
> What do you think 'rte_eth_dev_rss_hash_conf_get()' memset the 'rss_conf'
> param before passing it to the PMD? To prevent issues like above in user
> application.

I will move it to the else leg first in the v2 patch. Wait for more comments. Thanks!