From: Wen Gu <guwen@linux.alibaba.com>
To: kgraul@linux.ibm.com, davem@davemloft.net, kuba@kernel.org
Cc: linux-s390@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH net] net/smc: Transitional solution for clcsock race issue
Date: Fri, 21 Jan 2022 15:05:02 +0800 [thread overview]
Message-ID: <ad5c1c9b-5d9e-cd0f-88c7-4420bc9ed0e5@linux.alibaba.com> (raw)
In-Reply-To: <1642086177-130611-1-git-send-email-guwen@linux.alibaba.com>
On 2022/1/13 11:02 pm, Wen Gu wrote:
> We encountered a crash in smc_setsockopt() and it is caused by
> accessing smc->clcsock after clcsock was released.
>
> BUG: kernel NULL pointer dereference, address: 0000000000000020
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 0 P4D 0
> Oops: 0000 [#1] PREEMPT SMP PTI
> CPU: 1 PID: 50309 Comm: nginx Kdump: loaded Tainted: G E 5.16.0-rc4+ #53
> RIP: 0010:smc_setsockopt+0x59/0x280 [smc]
> Call Trace:
> <TASK>
> __sys_setsockopt+0xfc/0x190
> __x64_sys_setsockopt+0x20/0x30
> do_syscall_64+0x34/0x90
> entry_SYSCALL_64_after_hwframe+0x44/0xae
> RIP: 0033:0x7f16ba83918e
> </TASK>
>
> This patch tries to fix it by holding clcsock_release_lock and
> checking whether clcsock has already been released before access.
>
> In case that a crash of the same reason happens in smc_getsockopt()
> or smc_switch_to_fallback(), this patch also checkes smc->clcsock
> in them too. And the caller of smc_switch_to_fallback() will identify
> whether fallback succeeds according to the return value.
>
> Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
> ---
> net/smc/af_smc.c | 63 +++++++++++++++++++++++++++++++++++++++++++++-----------
> 1 file changed, 51 insertions(+), 12 deletions(-)
>
Sorry for bothering, just wonder if this patch needs further improvements?
The previous discussion can be found in:
https://lore.kernel.org/lkml/5dd7ffd1-28e2-24cc-9442-1defec27375e@linux.ibm.com/T/
I sent this patch with a new subject instead of sending a v2 of the previously
discussed patch because I think the original subject seems not appropriate anymore
after introducing check of clcsock in smc_switch_to_fallback().
Thanks,
Wen Gu
next prev parent reply other threads:[~2022-01-21 7:05 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-13 15:02 [PATCH net] net/smc: Transitional solution for clcsock race issue Wen Gu
2022-01-21 7:05 ` Wen Gu [this message]
2022-01-21 8:46 ` Karsten Graul
2022-01-21 9:11 ` Wen Gu
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