| Message ID | 20210905074936.15723-1-len.baker@gmx.com |
|---|---|
| State | New |
| Headers | show |
| Series | net/mlx5: DR, Prefer kcalloc over open coded arithmetic | expand |
On Sun, 2021-09-05 at 09:49 +0200, Len Baker wrote: > 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> applied to net-next-mlx5, Thanks.
On Sun, Sep 05, 2021 at 09:49:36AM +0200, Len Baker wrote: > 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> > --- > .../net/ethernet/mellanox/mlx5/core/steering/dr_action.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > 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 6475ba35cf6b..e8957dad3bb1 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_action.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_action.c > @@ -716,6 +716,7 @@ 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; > > @@ -724,11 +725,14 @@ 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); In the future, consider array3_size(), but this is fine too. :) -Kees > if (!ref_actions) > goto free_hw_dests; > > -- > 2.25.1 > -- Kees Cook
Hi, On Mon, Sep 20, 2021 at 09:06:35PM -0700, Kees Cook wrote: > > > > - 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); > > In the future, consider array3_size(), but this is fine too. :) Ok, thanks for the advise. Regards, Len
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 6475ba35cf6b..e8957dad3bb1 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_action.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/steering/dr_action.c @@ -716,6 +716,7 @@ 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; @@ -724,11 +725,14 @@ 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;
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> --- .../net/ethernet/mellanox/mlx5/core/steering/dr_action.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) -- 2.25.1