linux-kernel - Re: [PATCH] RDMA/hfi1: fix potential memory leak in setup_base

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Date:   Tue, 19 Jul 2022 08:26:39 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>
Cc:     Jianglei Nie <niejianglei2021@....com>, jgg@...pe.ca,
        linux-rdma@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] RDMA/hfi1: fix potential memory leak in setup_base_ctxt()

On Mon, Jul 18, 2022 at 09:56:48AM -0400, Dennis Dalessandro wrote:
> On 7/18/22 8:30 AM, Leon Romanovsky wrote:
> > On Mon, Jul 18, 2022 at 08:11:59AM -0400, Dennis Dalessandro wrote:
> >> On 7/18/22 6:39 AM, Leon Romanovsky wrote:
> >>> On Mon, Jul 11, 2022 at 07:52:25AM -0400, Dennis Dalessandro wrote:
> >>>> On 7/11/22 3:07 AM, Jianglei Nie wrote:
> >>>>> setup_base_ctxt() allocates a memory chunk for uctxt->groups with
> >>>>> hfi1_alloc_ctxt_rcv_groups(). When init_user_ctxt() fails, uctxt->groups
> >>>>> is not released, which will lead to a memory leak.
> >>>>>
> >>>>> We should release the uctxt->groups with hfi1_free_ctxt_rcv_groups()
> >>>>> when init_user_ctxt() fails.
> >>>>>
> >>>>> Signed-off-by: Jianglei Nie <niejianglei2021@....com>
> >>>>> ---
> >>>>>  drivers/infiniband/hw/hfi1/file_ops.c | 4 +++-
> >>>>>  1 file changed, 3 insertions(+), 1 deletion(-)
> >>>>>
> >>>>> diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/file_ops.c
> >>>>> index 2e4cf2b11653..629beff053ad 100644
> >>>>> --- a/drivers/infiniband/hw/hfi1/file_ops.c
> >>>>> +++ b/drivers/infiniband/hw/hfi1/file_ops.c
> >>>>> @@ -1179,8 +1179,10 @@ static int setup_base_ctxt(struct hfi1_filedata *fd,
> >>>>>  		goto done;
> >>>>>  
> >>>>>  	ret = init_user_ctxt(fd, uctxt);
> >>>>> -	if (ret)
> >>>>> +	if (ret) {
> >>>>> +		hfi1_free_ctxt_rcv_groups(uctxt);
> >>>>>  		goto done;
> >>>>> +	}
> >>>>>  
> >>>>>  	user_init(uctxt);
> >>>>>  
> >>>>
> >>>> Doesn't seem like this patch is correct. The free is done when the file is
> >>>> closed, along with other clean up stuff. See hfi1_file_close().
> >>>
> >>> Can setup_base_ctxt() be called twice for same uctxt?
> >>> You are allocating rcd->groups and not releasing.
> >>
> >> The first thing assign_ctxt() does is a check of the fd->uctxt and it bails with
> >> -EINVAL. So effectively only once.
> > 
> > I'm slightly confused. How will you release rcd->groups?
> > 
> > assign_ctxt()
> >  -> setup_base_ctxt()
> >    -> hfi1_alloc_ctxt_rcv_groups()
> >       ,,,
> >       rcd->groups = kzalloc...
> >       ...
> >    -> init_user_ctxt() <-- fails and leaves fd->uctx == NULL
> > 
> > 
> > ...
> > hfi1_file_close()
> >   struct hfi1_ctxtdata *uctxt = fdata->uctxt;
> >   ...
> >   if (!uctxt)             <-- This is our case
> >      goto done; 
> >   ...
> > 
> > done:
> >   if (refcount_dec_and_test(&dd->user_refcount))
> >      complete(&dd->user_comp);
> > 
> >   cleanup_srcu_struct(&fdata->pq_srcu);
> >   kfree(fdata);
> >   return 0;
> > 
> 
> Looks like this may have been broken with:
> 
> e87473bc1b6c ("IB/hfi1: Only set fd pointer when base context is completely
> initialized")
> 
> The question is does it make more sense to just move the fd->uctxt assignment
> up, or call the free directly. I think that might be opening a bigger can of
> worms though, as this was part of a larger patch set. Maybe it is best after all
> to go with this patch.
> 
> Let's add the above as a fixes line and tack on:
> 
> Acked-by: Dennis Dalessandro <dennis.dalessandro@...nelisnetworks.com>
> 
> It's been like this since 4.14, so no rush to get it in for the ultra late RC.
> I'll get it tested as part of the next cycle.
> 

Thanks, applied.