In the Linux kernel, the following vulnerability has been resolved:
wifi: iwlwifi: mvm: Fix a memory corruption issue
A few lines above, space is kzalloc()ed for: sizeof(struct iwl_nvm_data) + sizeof(struct ieee80211_channel) + sizeof(struct ieee80211_rate)
mvm->nvm_data is a struct iwl_nvm_data, so it is fine.
At the end of this structure, there is the channels flex array. Each element is of type struct ieee80211_channel. So only 1 element is allocated in this array.
When doing: mvm->nvm_data->bands[0].channels = mvm->nvm_data->channels; We point at the first element of the channels flex array. So this is fine.
However, when doing: mvm->nvm_data->bands[0].bitrates = (void *)((u8 *)mvm->nvm_data->channels + 1); because of the (u8 *) cast, we add only 1 to the address of the beginning of the flex array.
It is likely that we want point at the struct ieee80211_rate allocated just after.
Remove the spurious casting so that the pointer arithmetic works as expected.