Re: [PATCH net v2] octeontx2-pf: Fix potential memory leak in otx2_init_tc()

From: Ziyang Xuan (William)
Date: Sun Dec 04 2022 - 21:35:05 EST


> 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@xxxxxxxxxx>
>> ---
>> 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);

...
}

Hello Leon Romanovsky,

It will kfree(tc->tc_entries_bitmap) firstly, and otx2_tc_alloc_ent_bitmap()
is called by otx2_dl_mcam_count_set() and otx2_init_tc(). I am not sure their
sequence and whether it will cause double free for tc->tc_entries_bitmap. So
setting tc->tc_entries_bitmap to NULL is safe, I think.

Thank you!

>
>> + }
>> + return err;
>> }
>> EXPORT_SYMBOL(otx2_init_tc);
>>
>> --
>> 2.25.1
>>
> .
>