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Date:   Mon, 18 Jul 2022 15:30:43 +0300
From:   Leon Romanovsky <leon@kernel.org>
To:     Dennis Dalessandro <dennis.dalessandro@cornelisnetworks.com>
Cc:     Jianglei Nie <niejianglei2021@163.com>, jgg@ziepe.ca,
        linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] RDMA/hfi1: fix potential memory leak in setup_base_ctxt()
Message-ID: <YtVSc7aazgxVFHRa@unreal>
References: <20220711070718.2318320-1-niejianglei2021@163.com>
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 <YtU4eXQCVEPGnh9b@unreal>
 <be437471-0080-8e9c-978a-6029c7826335@cornelisnetworks.com>
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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@163.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;


> 
> -Denny
> 
>