[ Upstream commit d1b355438b8325a486f087e506d412c4e852f37b ]
efx_net_stats() (.ndo_get_stats64) can be called during an ethtool
selftest, during which time nic_data->mc_stats is NULL as the NIC has
been fini'd. In this case do not attempt to fetch the latest stats
from the hardware, else we will crash on a NULL dereference:
BUG: kernel NULL pointer dereference, address: 0000000000000038
RIP efx_nic_update_stats
abridged calltrace:
efx_ef10_update_stats_pf
efx_net_stats
dev_get_stats
dev_seq_printf_stats
Skipping the read is safe, we will simply give out stale stats.
To ensure that the free in efx_ef10_fini_nic() does not race against
efx_ef10_update_stats_pf(), which could cause a TOCTTOU bug, take the
efx->stats_lock in fini_nic (it is already held across update_stats).
Fixes: d3142c193d ("sfc: refactor EF10 stats handling")
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>
Signed-off-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
cb1aa7cc56