linux-kernel - drivers/net/ethernet/intel/ice/ice_main.c:5677 ice_update_vsi_tx_ring_stats() error: we previously assumed 'ring' could be null (see line 5673)

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Date:   Mon, 21 Feb 2022 16:09:14 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     kbuild@...ts.01.org,
        Maciej Fijalkowski <maciej.fijalkowski@...el.com>
Cc:     lkp@...el.com, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org,
        Tony Nguyen <anthony.l.nguyen@...el.com>
Subject: drivers/net/ethernet/intel/ice/ice_main.c:5677
 ice_update_vsi_tx_ring_stats() error: we previously assumed 'ring' could be
 null (see line 5673)

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   cfb92440ee71adcc2105b0890bb01ac3cddb8507
commit: e72bba21355dbb67512a0d666fec9f4b56dbfc2f ice: split ice_ring onto Tx/Rx separate structs
config: ia64-randconfig-m031-20220220 (https://download.01.org/0day-ci/archive/20220221/202202211208.RSlRUGsa-lkp@intel.com/config)
compiler: ia64-linux-gcc (GCC) 11.2.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Dan Carpenter <dan.carpenter@...cle.com>

smatch warnings:
drivers/net/ethernet/intel/ice/ice_main.c:5677 ice_update_vsi_tx_ring_stats() error: we previously assumed 'ring' could be null (see line 5673)

vim +/ring +5677 drivers/net/ethernet/intel/ice/ice_main.c

49d358e0e746dc Marta Plantykow        2020-05-15  5661  static void
e72bba21355dbb Maciej Fijalkowski     2021-08-19  5662  ice_update_vsi_tx_ring_stats(struct ice_vsi *vsi, struct ice_tx_ring **rings,
49d358e0e746dc Marta Plantykow        2020-05-15  5663  			     u16 count)
49d358e0e746dc Marta Plantykow        2020-05-15  5664  {
49d358e0e746dc Marta Plantykow        2020-05-15  5665  	struct rtnl_link_stats64 *vsi_stats = &vsi->net_stats;
49d358e0e746dc Marta Plantykow        2020-05-15  5666  	u16 i;
49d358e0e746dc Marta Plantykow        2020-05-15  5667  
49d358e0e746dc Marta Plantykow        2020-05-15  5668  	for (i = 0; i < count; i++) {
e72bba21355dbb Maciej Fijalkowski     2021-08-19  5669  		struct ice_tx_ring *ring;
e72bba21355dbb Maciej Fijalkowski     2021-08-19  5670  		u64 pkts = 0, bytes = 0;
49d358e0e746dc Marta Plantykow        2020-05-15  5671  
49d358e0e746dc Marta Plantykow        2020-05-15  5672  		ring = READ_ONCE(rings[i]);
e72bba21355dbb Maciej Fijalkowski     2021-08-19 @5673  		if (ring)
                                                                            ^^^^
Check for NULL

e72bba21355dbb Maciej Fijalkowski     2021-08-19  5674  			ice_fetch_u64_stats_per_ring(&ring->syncp, ring->stats, &pkts, &bytes);
49d358e0e746dc Marta Plantykow        2020-05-15  5675  		vsi_stats->tx_packets += pkts;
49d358e0e746dc Marta Plantykow        2020-05-15  5676  		vsi_stats->tx_bytes += bytes;
49d358e0e746dc Marta Plantykow        2020-05-15 @5677  		vsi->tx_restart += ring->tx_stats.restart_q;

Unchecked dereferences on the following lines

49d358e0e746dc Marta Plantykow        2020-05-15  5678  		vsi->tx_busy += ring->tx_stats.tx_busy;
49d358e0e746dc Marta Plantykow        2020-05-15  5679  		vsi->tx_linearize += ring->tx_stats.tx_linearize;
49d358e0e746dc Marta Plantykow        2020-05-15  5680  	}
49d358e0e746dc Marta Plantykow        2020-05-15  5681  }

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org