net/mlx5: DR, Prefer kcalloc over open coded arithmetic

As noted in the "Deprecated Interfaces, Language Features, Attributes,
and Conventions" documentation [1], size calculations (especially
multiplication) should not be performed in memory allocator (or similar)
function arguments due to the risk of them overflowing. This could lead
to values wrapping around and a smaller allocation being made than the
caller was expecting. Using those allocations could lead to linear
overflows of heap memory and other misbehaviors.

So, refactor the code a bit to use the purpose specific kcalloc()
function instead of the argument size * count in the kzalloc() function.

[1] https://www.kernel.org/doc/html/v5.14/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments

Signed-off-by: Len Baker <len.baker@gmx.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_action.c b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_action.c
index 5063011..0793684 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_action.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_action.c
@@ -854,6 +854,7 @@ mlx5dr_action_create_mult_dest_tbl(struct mlx5dr_domain *dmn,
        struct mlx5dr_action *action;
        bool reformat_req = false;
        u32 num_of_ref = 0;
+       u32 ref_act_cnt;
        int ret;
        int i;
 
@@ -862,11 +863,14 @@ mlx5dr_action_create_mult_dest_tbl(struct mlx5dr_domain *dmn,
                return NULL;
        }
 
-       hw_dests = kzalloc(sizeof(*hw_dests) * num_of_dests, GFP_KERNEL);
+       hw_dests = kcalloc(num_of_dests, sizeof(*hw_dests), GFP_KERNEL);
        if (!hw_dests)
                return NULL;
 
-       ref_actions = kzalloc(sizeof(*ref_actions) * num_of_dests * 2, GFP_KERNEL);
+       if (unlikely(check_mul_overflow(num_of_dests, 2u, &ref_act_cnt)))
+               goto free_hw_dests;
+
+       ref_actions = kcalloc(ref_act_cnt, sizeof(*ref_actions), GFP_KERNEL);
        if (!ref_actions)
                goto free_hw_dests;