From: Edward Cree ecree.xilinx@gmail.com
[ 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: d3142c193dca ("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 --- drivers/net/ethernet/sfc/ef10.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c index b63e47af63655..8c019f382a7f3 100644 --- a/drivers/net/ethernet/sfc/ef10.c +++ b/drivers/net/ethernet/sfc/ef10.c @@ -1297,8 +1297,10 @@ static void efx_ef10_fini_nic(struct efx_nic *efx) { struct efx_ef10_nic_data *nic_data = efx->nic_data;
+ spin_lock_bh(&efx->stats_lock); kfree(nic_data->mc_stats); nic_data->mc_stats = NULL; + spin_unlock_bh(&efx->stats_lock); }
static int efx_ef10_init_nic(struct efx_nic *efx) @@ -1852,9 +1854,14 @@ static size_t efx_ef10_update_stats_pf(struct efx_nic *efx, u64 *full_stats,
efx_ef10_get_stat_mask(efx, mask);
- efx_nic_copy_stats(efx, nic_data->mc_stats); - efx_nic_update_stats(efx_ef10_stat_desc, EF10_STAT_COUNT, - mask, stats, nic_data->mc_stats, false); + /* If NIC was fini'd (probably resetting), then we can't read + * updated stats right now. + */ + if (nic_data->mc_stats) { + efx_nic_copy_stats(efx, nic_data->mc_stats); + efx_nic_update_stats(efx_ef10_stat_desc, EF10_STAT_COUNT, + mask, stats, nic_data->mc_stats, false); + }
/* Update derived statistics */ efx_nic_fix_nodesc_drop_stat(efx,