From: Karsten Graul <kgraul@linux.ibm.com>
To: Dust Li <dust.li@linux.alibaba.com>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>
Cc: linux-s390@vger.kernel.org, netdev@vger.kernel.org,
Wen Gu <guwen@linux.alibaba.com>,
Tony Lu <tonylu@linux.alibaba.com>
Subject: Re: [PATCH net 2/2] net/smc: fix kernel panic caused by race of smc_sock
Date: Wed, 29 Dec 2021 13:33:20 +0100 [thread overview]
Message-ID: <444f15e6-db60-3e86-fe20-32f24928844c@linux.ibm.com> (raw)
In-Reply-To: <20211228090325.27263-3-dust.li@linux.alibaba.com>
On 28/12/2021 10:03, Dust Li wrote:
> A crash occurs when smc_cdc_tx_handler() tries to access smc_sock
> but smc_release() has already freed it.
I am not sure about what happened here.
Your patch removes the whole dismisser concept that was introduced to
solve exactly the problem you describe. And you implemented a different approach.
In theory, when smc_cdc_tx_handler() is called but the connection is already
freed than the connection should have gone through smc_cdc_tx_dismiss_slots(),
called by smc_conn_kill() or smc_conn_free(). If that happened there would be no
access to an already freed address in smc_cdc_tx_handler().
Can you explain why the code reached smc_cdc_tx_handler() with cdcpend->conn
pointing to a connection that is already freed? I think if there is a bug it should
be fixed instead of replacing the code by a new construct.
Thoughts?
next prev parent reply other threads:[~2021-12-29 12:33 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-28 9:03 [PATCH net 0/2] net/smc: fix kernel panic caused by race of smc_sock Dust Li
2021-12-28 9:03 ` [PATCH net 1/2] net/smc: don't send CDC/LLC message if link not ready Dust Li
2021-12-29 12:36 ` Karsten Graul
2021-12-30 3:02 ` dust.li
2021-12-30 18:55 ` Karsten Graul
2021-12-31 3:15 ` dust.li
2022-01-03 10:40 ` Karsten Graul
2021-12-31 6:08 ` [PATCH net] net/smc: add comments for smc_link_{usable|sendable} Dust Li
2022-01-02 16:20 ` patchwork-bot+netdevbpf
2021-12-28 9:03 ` [PATCH net 2/2] net/smc: fix kernel panic caused by race of smc_sock Dust Li
2021-12-29 12:33 ` Karsten Graul [this message]
2021-12-30 3:46 ` dust.li
2021-12-28 12:50 ` [PATCH net 0/2] " patchwork-bot+netdevbpf
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