On 9/19/21 06:40, 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, use the struct_size() helper to do the arithmetic instead of the
> argument "size + count * size" in the kzalloc() functions.
>
> Also, take the opportunity to refactor the memcpy() call to use the
> flex_array_size() helper.
>
> [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#open-coded-arithmetic-in-allocator-arguments
>
> Signed-off-by: Len Baker <[email protected]>
> ---
> net/wireless/nl80211.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
> index bf7cd4752547..b56856349ced 100644
> --- a/net/wireless/nl80211.c
> +++ b/net/wireless/nl80211.c
> @@ -11766,9 +11766,10 @@ static int nl80211_set_cqm_rssi(struct genl_info *info,
> wdev_lock(wdev);
> if (n_thresholds) {
> struct cfg80211_cqm_config *cqm_config;
> + size_t size = struct_size(cqm_config, rssi_thresholds,
> + n_thresholds);
>
> - cqm_config = kzalloc(sizeof(struct cfg80211_cqm_config) +
> - n_thresholds * sizeof(s32), GFP_KERNEL);
> + cqm_config = kzalloc(size, GFP_KERNEL);
I don't think variable _size_ is needed here; this is just fine:
- cqm_config = kzalloc(sizeof(struct cfg80211_cqm_config) +
- n_thresholds * sizeof(s32), GFP_KERNEL);
+ cqm_config = kzalloc(struct_size(cqm_config, rssi_thresholds,
+ n_thresholds), GFP_KERNEL);
Thanks
--
Gustavo
> if (!cqm_config) {
> err = -ENOMEM;
> goto unlock;
> @@ -11777,7 +11778,8 @@ static int nl80211_set_cqm_rssi(struct genl_info *info,
> cqm_config->rssi_hyst = hysteresis;
> cqm_config->n_rssi_thresholds = n_thresholds;
> memcpy(cqm_config->rssi_thresholds, thresholds,
> - n_thresholds * sizeof(s32));
> + flex_array_size(cqm_config, rssi_thresholds,
> + n_thresholds));
>
> wdev->cqm_config = cqm_config;
> }
> @@ -15081,9 +15083,7 @@ static int nl80211_set_sar_specs(struct sk_buff *skb, struct genl_info *info)
> if (specs > rdev->wiphy.sar_capa->num_freq_ranges)
> return -EINVAL;
>
> - sar_spec = kzalloc(sizeof(*sar_spec) +
> - specs * sizeof(struct cfg80211_sar_sub_specs),
> - GFP_KERNEL);
> + sar_spec = kzalloc(struct_size(sar_spec, sub_specs, specs), GFP_KERNEL);
> if (!sar_spec)
> return -ENOMEM;
>
> --
> 2.25.1
>