sfc: Fix use-after-free due to selftest_work
There is a use-after-free scenario that is: When the NIC is down, user set mac address or vlan tag to VF, the xxx_set_vf_mac() or xxx_set_vf_vlan() will invoke efx_net_stop() and efx_net_open(), since netif_running() is false, the port will not start and keep port_enabled false, but selftest_work is scheduled in efx_net_open(). If we remove the device before selftest_work run, the efx_stop_port() will not be called since the NIC is down, and then efx is freed, we will soon get a UAF in run_timer_softirq() like this: [ 1178.907941] ================================================================== [ 1178.907948] BUG: KASAN: use-after-free in run_timer_softirq+0xdea/0xe90 [ 1178.907950] Write of size 8 at addr ff11001f449cdc80 by task swapper/47/0 [ 1178.907950] [ 1178.907953] CPU: 47 PID: 0 Comm: swapper/47 Kdump: loaded Tainted: G O --------- -t - 4.18.0 #1 [ 1178.907954] Hardware name: SANGFOR X620G40/WI2HG-208T1061A, BIOS SPYH051032-U01 04/01/2022 [ 1178.907955] Call Trace: [ 1178.907956] <IRQ> [ 1178.907960] dump_stack+0x71/0xab [ 1178.907963] print_address_description+0x6b/0x290 [ 1178.907965] ? run_timer_softirq+0xdea/0xe90 [ 1178.907967] kasan_report+0x14a/0x2b0 [ 1178.907968] run_timer_softirq+0xdea/0xe90 [ 1178.907971] ? init_timer_key+0x170/0x170 [ 1178.907973] ? hrtimer_cancel+0x20/0x20 [ 1178.907976] ? sched_clock+0x5/0x10 [ 1178.907978] ? sched_clock_cpu+0x18/0x170 [ 1178.907981] __do_softirq+0x1c8/0x5fa [ 1178.907985] irq_exit+0x213/0x240 [ 1178.907987] smp_apic_timer_interrupt+0xd0/0x330 [ 1178.907989] apic_timer_interrupt+0xf/0x20 [ 1178.907990] </IRQ> [ 1178.907991] RIP: 0010:mwait_idle+0xae/0x370 If the NIC is not actually brought up, there is no need to schedule selftest_work, so let's move invoking efx_selftest_async_start() into efx_start_all(), and it will be canceled by broughting down. Fixes: dd40781e ("sfc: Run event/IRQ self-test asynchronously when interface is brought up") Fixes: e340be92 ("sfc: add ndo_set_vf_mac() function for EF10") Debugged-by:Huang Cun <huangcun@sangfor.com.cn> Cc: Donglin Peng <pengdonglin@sangfor.com.cn> Suggested-by: