net/smc: Avoid overwriting the copies of clcsock callback functions

mainline inclusion
from mainline-v5.17-rc5
commit 1de9770d
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IA72JN
CVE: CVE-2022-48721

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1de9770d121ee9294794cca0e0be8fbfa0134ee8



--------------------------------

The callback functions of clcsock will be saved and replaced during
the fallback. But if the fallback happens more than once, then the
copies of these callback functions will be overwritten incorrectly,
resulting in a loop call issue:

clcsk->sk_error_report
 |- smc_fback_error_report() <------------------------------|
     |- smc_fback_forward_wakeup()                          | (loop)
         |- clcsock_callback()  (incorrectly overwritten)   |
             |- smc->clcsk_error_report() ------------------|

So this patch fixes the issue by saving these function pointers only
once in the fallback and avoiding overwriting.

Reported-by:  <syzbot+4de3c0e8a263e1e499bc@syzkaller.appspotmail.com>
Fixes: 341adeec ("net/smc: Forward wakeup to smc socket waitqueue after fallback")
Link: https://lore.kernel.org/r/0000000000006d045e05d78776f6@google.com


Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Conflicts:
	net/smc/af_smc.c
[The conflict occurs because the commit c0bf3d8a("net/smc:
Transitional solution for clcsock race issue") and
e0e4b8fa("net/smc: Add SMC statistics support") are not
merged]
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>