9p/net: fix missing error check in p9_check_errors

stable inclusion
from stable-5.10.80
commit 32246cefb9920e6f72a121f43cc3e06037fab63c
bugzilla: 185821 https://gitee.com/openeuler/kernel/issues/I4L7CG

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=32246cefb9920e6f72a121f43cc3e06037fab63c

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

commit 27eb4c31 upstream.

Link: https://lkml.kernel.org/r/99338965-d36c-886e-cd0e-1d8fff2b4746@gmail.com


Reported-by:  <syzbot+06472778c97ed94af66d@syzkaller.appspotmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Dominique Martinet <asmadeus@codewreck.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>

Signed-off-by: Chen Jun <chenjun102@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>