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Subject: Re: [PATCH] fuse: Put leaked request on error path of fuse_retrieve()
To:     Miklos Szeredi <miklos@szeredi.hu>
Cc:     linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org
References: <154149557692.17196.12607896696117775780.stgit@localhost.localdomain>
 <CAJfpegtMmrvnZE3xtMDNTmF=pSmqFROtehamivbLeAh2E_qZ6Q@mail.gmail.com>
From:   Kirill Tkhai <ktkhai@virtuozzo.com>
Message-ID: <b3162ccb-f6d8-b0d4-5cfe-313e89c49a1d@virtuozzo.com>
Date:   Tue, 6 Nov 2018 12:25:47 +0300
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On 06.11.2018 12:23, Miklos Szeredi wrote:
> On Tue, Nov 6, 2018 at 10:13 AM, Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
>> fuse_request_send_notify_reply() may fail, and this case
>> it remains leaked (fuse_retrieve_end(), which is called
>> on error path, does not do that). Also, fc->num_waiting,
>> will never be decremented, and fuse_wait_aborted() will
>> never finish. So, put the request patently.
>>
>> Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
> 
> Posted same patch yesterday for a syzbot report.   How did you notice this?

I've found this by code review. I did this last week and I have 10 patches more
on different theme. I was waiting for when the merge window opens.
 
> 
>> ---
>>  fs/fuse/dev.c |    4 +++-
>>  1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
>> index ae813e609932..6fe330cc9709 100644
>> --- a/fs/fuse/dev.c
>> +++ b/fs/fuse/dev.c
>> @@ -1768,8 +1768,10 @@ static int fuse_retrieve(struct fuse_conn *fc, struct inode *inode,
>>         req->in.args[1].size = total_len;
>>
>>         err = fuse_request_send_notify_reply(fc, req, outarg->notify_unique);
>> -       if (err)
>> +       if (err) {
>>                 fuse_retrieve_end(fc, req);
>> +               fuse_put_request(fc, req);
>> +       }
>>
>>         return err;
>>  }
>>