drivers/net/ethernet/mellanox/mlx5/core/fs_core.c:1555 dest_is_valid() error: we previously assumed 'dest' could be null (see line 1545)

[Dan Carpenter]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   581cb3a26baf846ee9636214afaa5333919875b1
commit: ff189b43568216c6211e9e7ddd9026cb8295e744 net/mlx5: Add ignore level support fwd to table rules
config: powerpc-randconfig-m031-20200911 (attached as .config)
compiler: powerpc64-linux-gcc (GCC) 9.3.0

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

New smatch warnings:
drivers/net/ethernet/mellanox/mlx5/core/fs_core.c:1555 dest_is_valid() error: we previously assumed 'dest' could be null (see line 1545)

# https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ff189b43568216c6211e9e7ddd9026cb8295e744
git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
git fetch --no-tags linus master
git checkout ff189b43568216c6211e9e7ddd9026cb8295e744
vim +/dest +1555 drivers/net/ethernet/mellanox/mlx5/core/fs_core.c

d63cd28608bb563 Maor Gottlieb 2016-04-29  1538  static bool dest_is_valid(struct mlx5_flow_destination *dest,
ff189b43568216c Paul Blakey   2020-01-05  1539  			  struct mlx5_flow_act *flow_act,
d63cd28608bb563 Maor Gottlieb 2016-04-29  1540  			  struct mlx5_flow_table *ft)
d63cd28608bb563 Maor Gottlieb 2016-04-29  1541  {
ff189b43568216c Paul Blakey   2020-01-05  1542  	bool ignore_level = flow_act->flags & FLOW_ACT_IGNORE_FLOW_LEVEL;
ff189b43568216c Paul Blakey   2020-01-05  1543  	u32 action = flow_act->action;
ff189b43568216c Paul Blakey   2020-01-05  1544  
bd5251dbf156b6b Amir Vadai    2016-05-13 @1545  	if (dest && (dest->type == MLX5_FLOW_DESTINATION_TYPE_COUNTER))
                                                            ^^^^
Check for NULL.

171c7625bef9998 Mark Bloch    2018-10-03  1546  		return counter_is_valid(action);
bd5251dbf156b6b Amir Vadai    2016-05-13  1547  
d63cd28608bb563 Maor Gottlieb 2016-04-29  1548  	if (!(action & MLX5_FLOW_CONTEXT_ACTION_FWD_DEST))
d63cd28608bb563 Maor Gottlieb 2016-04-29  1549  		return true;
d63cd28608bb563 Maor Gottlieb 2016-04-29  1550  
ff189b43568216c Paul Blakey   2020-01-05  1551  	if (ignore_level) {
ff189b43568216c Paul Blakey   2020-01-05  1552  		if (ft->type != FS_FT_FDB)
ff189b43568216c Paul Blakey   2020-01-05  1553  			return false;
ff189b43568216c Paul Blakey   2020-01-05  1554  
ff189b43568216c Paul Blakey   2020-01-05 @1555  		if (dest->type == MLX5_FLOW_DESTINATION_TYPE_FLOW_TABLE &&
                                                                    ^^^^^^^^^^
Unchecked dereference.

ff189b43568216c Paul Blakey   2020-01-05  1556  		    dest->ft->type != FS_FT_FDB)
ff189b43568216c Paul Blakey   2020-01-05  1557  			return false;
ff189b43568216c Paul Blakey   2020-01-05  1558  	}
ff189b43568216c Paul Blakey   2020-01-05  1559  
d63cd28608bb563 Maor Gottlieb 2016-04-29  1560  	if (!dest || ((dest->type ==
                                                            ^^^^^
Check.

d63cd28608bb563 Maor Gottlieb 2016-04-29  1561  	    MLX5_FLOW_DESTINATION_TYPE_FLOW_TABLE) &&
ff189b43568216c Paul Blakey   2020-01-05  1562  	    (dest->ft->level <= ft->level && !ignore_level)))
d63cd28608bb563 Maor Gottlieb 2016-04-29  1563  		return false;
d63cd28608bb563 Maor Gottlieb 2016-04-29  1564  	return true;
d63cd28608bb563 Maor Gottlieb 2016-04-29  1565  }

---
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