netdev - [BUG] net: rds: rds_send

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Date:   Sun, 14 Mar 2021 11:23:10 +0300
From:   Fatih Yildirim <yildirim.fatih@...il.com>
To:     santosh.shilimkar@...cle.com, davem@...emloft.net, kuba@...nel.org
Cc:     gregkh@...uxfoundation.org, netdev@...r.kernel.org,
        linux-rdma@...r.kernel.org, rds-devel@....oracle.com,
        linux-kernel@...r.kernel.org
Subject: [BUG] net: rds: rds_send_probe memory leak

Hi Santosh,

I've been working on a memory leak bug reported by syzbot.
https://syzkaller.appspot.com/bug?id=39b72114839a6dbd66c1d2104522698a813f9ae2

It seems that memory allocated in rds_send_probe function is not freed.

Let me share my observations.
rds_message is allocated at the beginning of rds_send_probe function.
Then it is added to cp_send_queue list of rds_conn_path and refcount
is increased by one.
Next, in rds_send_xmit function it is moved from cp_send_queue list to
cp_retrans list, and again refcount is increased by one.
Finally in rds_loop_xmit function refcount is increased by one.
So, total refcount is 4.
However, rds_message_put is called three times, in rds_send_probe,
rds_send_remove_from_sock and rds_send_xmit functions. It seems that
one more rds_message_put is needed.
Would you please check and share your comments on this issue?

Thanks,
Fatih