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Message-ID: <c7b8017b-2234-92f5-de3a-f189d52f4da8@linux.alibaba.com>
Date: Thu, 28 Dec 2023 19:02:31 +0800
From: Wen Gu <guwen@...ux.alibaba.com>
To: Tony Lu <tonylu@...ux.alibaba.com>
Cc: wenjia@...ux.ibm.com, jaka@...ux.ibm.com, davem@...emloft.net,
edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
alibuda@...ux.alibaba.com, ubraun@...ux.vnet.ibm.com,
linux-s390@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net/smc: fix invalid link access in dumping SMC-R
connections
On 2023/12/28 17:32, Tony Lu wrote:
> On Wed, Dec 27, 2023 at 03:40:35PM +0800, Wen Gu wrote:
>> A crash was found when dumping SMC-R connections. It can be reproduced
>> by following steps:
>>
>> - environment: two RNICs on both sides.
>> - run SMC-R between two sides, now a SMC_LGR_SYMMETRIC type link group
>> will be created.
>> - set the first RNIC down on either side and link group will turn to
>> SMC_LGR_ASYMMETRIC_LOCAL then.
>> - run 'smcss -R' and the crash will be triggered.
>>
>> BUG: kernel NULL pointer dereference, address: 0000000000000010
>> #PF: supervisor read access in kernel mode
>> #PF: error_code(0x0000) - not-present page
>> PGD 8000000101fdd067 P4D 8000000101fdd067 PUD 10ce46067 PMD 0
>> Oops: 0000 [#1] PREEMPT SMP PTI
>> CPU: 3 PID: 1810 Comm: smcss Kdump: loaded Tainted: G W E 6.7.0-rc6+ #51
>> RIP: 0010:__smc_diag_dump.constprop.0+0x36e/0x620 [smc_diag]
>> Call Trace:
>> <TASK>
>> ? __die+0x24/0x70
>> ? page_fault_oops+0x66/0x150
>> ? exc_page_fault+0x69/0x140
>> ? asm_exc_page_fault+0x26/0x30
>> ? __smc_diag_dump.constprop.0+0x36e/0x620 [smc_diag]
>> smc_diag_dump_proto+0xd0/0xf0 [smc_diag]
>> smc_diag_dump+0x26/0x60 [smc_diag]
>> netlink_dump+0x19f/0x320
>> __netlink_dump_start+0x1dc/0x300
>> smc_diag_handler_dump+0x6a/0x80 [smc_diag]
>> ? __pfx_smc_diag_dump+0x10/0x10 [smc_diag]
>> sock_diag_rcv_msg+0x121/0x140
>> ? __pfx_sock_diag_rcv_msg+0x10/0x10
>> netlink_rcv_skb+0x5a/0x110
>> sock_diag_rcv+0x28/0x40
>> netlink_unicast+0x22a/0x330
>> netlink_sendmsg+0x240/0x4a0
>> __sock_sendmsg+0xb0/0xc0
>> ____sys_sendmsg+0x24e/0x300
>> ? copy_msghdr_from_user+0x62/0x80
>> ___sys_sendmsg+0x7c/0xd0
>> ? __do_fault+0x34/0x1a0
>> ? do_read_fault+0x5f/0x100
>> ? do_fault+0xb0/0x110
>> __sys_sendmsg+0x4d/0x80
>> do_syscall_64+0x45/0xf0
>> entry_SYSCALL_64_after_hwframe+0x6e/0x76
>>
>> When the first RNIC is set down, the lgr->lnk[0] will be cleared and an
>> asymmetric link will be allocated in lgr->link[SMC_LINKS_PER_LGR_MAX - 1]
>> by smc_llc_alloc_alt_link(). Then when we try to dump SMC-R connections
>> in __smc_diag_dump(), the invalid lgr->lnk[0] will be accessed, resulting
>> in this issue. So fix it by accessing the right link.
>>
>> Fixes: f16a7dd5cf27 ("smc: netlink interface for SMC sockets")
>> Reported-by: henaumars <henaumars@...a.com>
>> Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7616
>
> What about using Link: http... here?
>
Thank you, Tony.
According to [1],
"
The Reported-by tag gives credit to people who find bugs and report them and it
hopefully inspires them to help us again in the future. The tag is intended for
bugs; please do not use it to credit feature requests. The tag should be followed
by a Closes: tag pointing to the report, unless the report is not available on
the web. The Link: tag can be used instead of Closes: if the patch fixes a part
of the issue(s) being reported.
"
So I guess the Closes: tag is fine here.
[1] https://docs.kernel.org/process/submitting-patches.html
>> Signed-off-by: Wen Gu <guwen@...ux.alibaba.com>
>
> Reviewed-by: Tony Lu <tonylu@...ux.alibaba.com>
>
>> ---
>> net/smc/smc_diag.c | 3 +--
>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/net/smc/smc_diag.c b/net/smc/smc_diag.c
>> index a584613aca12..5cc376834c57 100644
>> --- a/net/smc/smc_diag.c
>> +++ b/net/smc/smc_diag.c
>> @@ -153,8 +153,7 @@ static int __smc_diag_dump(struct sock *sk, struct sk_buff *skb,
>> .lnk[0].link_id = link->link_id,
>> };
>>
>> - memcpy(linfo.lnk[0].ibname,
>> - smc->conn.lgr->lnk[0].smcibdev->ibdev->name,
>> + memcpy(linfo.lnk[0].ibname, link->smcibdev->ibdev->name,
>> sizeof(link->smcibdev->ibdev->name));
>> smc_gid_be16_convert(linfo.lnk[0].gid, link->gid);
>> smc_gid_be16_convert(linfo.lnk[0].peer_gid, link->peer_gid);
>> --
>> 2.43.0
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