Re: [PATCH net v4 2/2] iavf: Fix out-of-bounds when setting channels on remove

[Chittim, Madhu]

On 5/3/2023 9:29 AM, Leon Romanovsky wrote:
> On Wed, May 03, 2023 at 10:00:49PM +0800, Ding Hui wrote:
> > On 2023/5/3 4:24 下午, Leon Romanovsky wrote:
> > > On Wed, May 03, 2023 at 11:15:41AM +0800, Ding Hui wrote:
> >
> > > > If we detected removing is in processing, we can avoid unnecessary
> > > > waiting and return error faster.
> > > >
> > > > On the other hand in timeout handling, we should keep the original
> > > > num_active_queues and reset num_req_queues to 0.
> > > >
> > > > Fixes: 4e5e6b5d9d13 ("iavf: Fix return of set the new channel count")
> > > > Signed-off-by: Ding Hui <dinghui@xxxxxxxxxxxxxx>
> > > > Cc: Donglin Peng <pengdonglin@xxxxxxxxxxxxxx>
> > > > Cc: Huang Cun <huangcun@xxxxxxxxxxxxxx>
> > > > Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxx>
> > > > Reviewed-by: Michal Kubiak <michal.kubiak@xxxxxxxxx>
> > > > ---
> > > > v3 to v4:
> > > >     - nothing changed
> > > >
> > > > v2 to v3:
> > > >     - fix review tag
> > > >
> > > > v1 to v2:
> > > >     - add reproduction script
> > > >
> > > > ---
> > > >    drivers/net/ethernet/intel/iavf/iavf_ethtool.c | 4 +++-
> > > >    1 file changed, 3 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
> > > > index 6f171d1d85b7..d8a3c0cfedd0 100644
> > > > --- a/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
> > > > +++ b/drivers/net/ethernet/intel/iavf/iavf_ethtool.c
> > > > @@ -1857,13 +1857,15 @@ static int iavf_set_channels(struct net_device *netdev,
> > > >    	/* wait for the reset is done */
> > > >    	for (i = 0; i < IAVF_RESET_WAIT_COMPLETE_COUNT; i++) {
> > > >    		msleep(IAVF_RESET_WAIT_MS);
> > > > +		if (test_bit(__IAVF_IN_REMOVE_TASK, &adapter->crit_section))
> > > > +			return -EOPNOTSUPP;
> > >
> > > This makes no sense without locking as change to __IAVF_IN_REMOVE_TASK
> > > can happen any time.
> >
> > The state doesn't need to be that precise here, it is optimized only for
> > the fast path. During the lifecycle of the adapter, the __IAVF_IN_REMOVE_TASK
> > state will only be set and not cleared.
> >
> > If we didn't detect the "removing" state, we also can fallback to timeout
> > handling.
> >
> > So I don't think the locking is necessary here, what do the maintainers
> > at Intel think?
>
> I'm not Intel maintainer, but your change, explanation and the following
> line from your commit message aren't really aligned.
>
> [ 3510.400799] ==================================================================
> [ 3510.400820] BUG: KASAN: slab-out-of-bounds in iavf_free_all_tx_resources+0x156/0x160 [iavf]

__IAVF_IN_REMOVE_TASK is being set only in iavf_remove() and the above 
change is ok in terms of coming out of setting channels early enough 
while remove is in progress.

Reviewed-by: madhu.chittim@xxxxxxxxx

> > > Thanks
> > >
> > > >    		if (adapter->flags & IAVF_FLAG_RESET_PENDING)
> > > >    			continue;
> > > >    		break;
> > > >    	}
> > > >    	if (i == IAVF_RESET_WAIT_COMPLETE_COUNT) {
> > > >    		adapter->flags &= ~IAVF_FLAG_REINIT_ITR_NEEDED;
> > > > -		adapter->num_active_queues = num_req;
> > > > +		adapter->num_req_queues = 0;
> > > >    		return -EOPNOTSUPP;
> > > >    	}
> > > > --
> > > > 2.17.1
> >
> > --
> > Thanks,
> > -dinghui