netdev - Re: [PATCH net v2] octeontx2-pf: Fix potential memory leak in otx2_init

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Date:   Mon, 5 Dec 2022 09:59:02 +0200
From:   Leon Romanovsky <leon@...nel.org>
To:     "Ziyang Xuan (William)" <william.xuanziyang@...wei.com>
Cc:     sgoutham@...vell.com, gakula@...vell.com, sbhatta@...vell.com,
        hkelam@...vell.com, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net v2] octeontx2-pf: Fix potential memory leak in
 otx2_init_tc()

On Mon, Dec 05, 2022 at 10:31:02AM +0800, Ziyang Xuan (William) wrote:
> > On Fri, Dec 02, 2022 at 07:04:30PM +0800, Ziyang Xuan wrote:
> >> In otx2_init_tc(), if rhashtable_init() failed, it does not free
> >> tc->tc_entries_bitmap which is allocated in otx2_tc_alloc_ent_bitmap().
> >>
> >> Fixes: 2e2a8126ffac ("octeontx2-pf: Unify flow management variables")
> >> Signed-off-by: Ziyang Xuan <william.xuanziyang@...wei.com>
> >> ---
> >> v2:
> >>   - Remove patch 2 which is not a problem, see the following link:
> >>     https://www.spinics.net/lists/netdev/msg864159.html
> >> ---
> >>  drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c | 7 ++++++-
> >>  1 file changed, 6 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c
> >> index e64318c110fd..6a01ab1a6e6f 100644
> >> --- a/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c
> >> +++ b/drivers/net/ethernet/marvell/octeontx2/nic/otx2_tc.c
> >> @@ -1134,7 +1134,12 @@ int otx2_init_tc(struct otx2_nic *nic)
> >>  		return err;
> >>  
> >>  	tc->flow_ht_params = tc_flow_ht_params;
> >> -	return rhashtable_init(&tc->flow_table, &tc->flow_ht_params);
> >> +	err = rhashtable_init(&tc->flow_table, &tc->flow_ht_params);
> >> +	if (err) {
> >> +		kfree(tc->tc_entries_bitmap);
> >> +		tc->tc_entries_bitmap = NULL;
> > 
> > Why do you set NULL here? All callers of otx2_init_tc() unwind error
> > properly.
> 
> See the implementation of otx2_tc_alloc_ent_bitmap() as following:
> 
> int otx2_tc_alloc_ent_bitmap(struct otx2_nic *nic)
> {
> 	struct otx2_tc_info *tc = &nic->tc_info;
> 
> 	if (!nic->flow_cfg->max_flows)
> 		return 0;
> 
> 	/* Max flows changed, free the existing bitmap */
> 	kfree(tc->tc_entries_bitmap);

It is worthless call for probe() calls as tc->tc_entries_bitmap is always NULL
at this point for them.

The kfree(tc->tc_entries_bitmap); needs to be moved into otx2_dl_mcam_count_set()
as it is the one place which can change bitmap.

But ok, it is probably too much to request.

Thanks,
Reviewed-by: Leon Romanovsky <leonro@...dia.com>