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Message-ID: <38e13999-b44d-40eb-96d9-01d4a3f4594e@embeddedor.com> Date: Fri, 13 Sep 2024 10:03:50 +0200 From: "Gustavo A. R. Silva" <gustavo@...eddedor.com> To: "Gustavo A. R. Silva" <gustavoars@...nel.org>, Miri Korenblit <miriam.rachel.korenblit@...el.com>, Kalle Valo <kvalo@...nel.org> Cc: linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org Subject: Re: [PATCH][next] wifi: iwlwifi: fw/mvm: Avoid multiple -Wflex-array-member-not-at-end warnings Hi all, Friendly ping: who can take this, please? 🙂 Thanks -- Gustavo On 15/08/24 21:54, Gustavo A. R. Silva wrote: > -Wflex-array-member-not-at-end was introduced in GCC-14, and we are > getting ready to enable it, globally. > > So, in order to avoid ending up with a flexible-array member in the > middle of multiple other structs, we use the `__struct_group()` > helper to create a new tagged `struct iwl_tx_cmd_hdr`. This structure > groups together all the members of the flexible `struct iwl_tx_cmd` > except the flexible array. > > As a result, the array is effectively separated from the rest of the > members without modifying the memory layout of the flexible structure. > We then change the type of the middle struct members currently causing > trouble from `struct iwl_tx_cmd` to `struct iwl_tx_cmd_hdr`. > > We also want to ensure that when new members need to be added to the > flexible structure, they are always included within the newly created > tagged struct. For this, we use `static_assert()`. This ensures that the > memory layout for both the flexible structure and the new tagged struct > is the same after any changes. > > This approach avoids having to implement `struct iwl_tx_cmd_hdr` > as a completely separate structure, thus preventing having to maintain > two independent but basically identical structures, closing the door > to potential bugs in the future. > > We also use `container_of()` whenever we need to retrieve a pointer to > the flexible structure, through which we can access the flexible-array > member, if necessary. > > Worth mentioning is that the union at the end of the flexible structure > was replaced by a direct declaration of flexible-array member `hdr[]` > as `payload` is unnecessary. > > So, with these changes, fix the following warnings: > > drivers/net/wireless/intel/iwlwifi/fw/api/tx.h:745:27: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > drivers/net/wireless/intel/iwlwifi/fw/api/tx.h:764:27: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > drivers/net/wireless/intel/iwlwifi/mvm/../fw/api/tdls.h:134:27: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > drivers/net/wireless/intel/iwlwifi/mvm/../fw/api/tdls.h:53:27: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > drivers/net/wireless/intel/iwlwifi/mvm/../fw/api/tx.h:745:27: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > drivers/net/wireless/intel/iwlwifi/mvm/../fw/api/tx.h:764:27: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end] > > Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org> > --- > .../net/wireless/intel/iwlwifi/fw/api/tdls.h | 4 +- > .../net/wireless/intel/iwlwifi/fw/api/tx.h | 61 ++++++++++--------- > .../net/wireless/intel/iwlwifi/mvm/mac-ctxt.c | 8 ++- > drivers/net/wireless/intel/iwlwifi/mvm/tdls.c | 8 ++- > 4 files changed, 45 insertions(+), 36 deletions(-) > > diff --git a/drivers/net/wireless/intel/iwlwifi/fw/api/tdls.h b/drivers/net/wireless/intel/iwlwifi/fw/api/tdls.h > index 893438aadab0..0ea6c0e37750 100644 > --- a/drivers/net/wireless/intel/iwlwifi/fw/api/tdls.h > +++ b/drivers/net/wireless/intel/iwlwifi/fw/api/tdls.h > @@ -50,7 +50,7 @@ struct iwl_tdls_channel_switch_timing { > */ > struct iwl_tdls_channel_switch_frame { > __le32 switch_time_offset; > - struct iwl_tx_cmd tx_cmd; > + struct iwl_tx_cmd_hdr tx_cmd; > u8 data[IWL_TDLS_CH_SW_FRAME_MAX_SIZE]; > } __packed; /* TDLS_STA_CHANNEL_SWITCH_FRAME_API_S_VER_1 */ > > @@ -131,7 +131,7 @@ struct iwl_tdls_config_cmd { > struct iwl_tdls_sta_info sta_info[IWL_MVM_TDLS_STA_COUNT]; > > __le32 pti_req_data_offset; > - struct iwl_tx_cmd pti_req_tx_cmd; > + struct iwl_tx_cmd_hdr pti_req_tx_cmd; > u8 pti_req_template[]; > } __packed; /* TDLS_CONFIG_CMD_API_S_VER_1 */ > > diff --git a/drivers/net/wireless/intel/iwlwifi/fw/api/tx.h b/drivers/net/wireless/intel/iwlwifi/fw/api/tx.h > index c5277e2f8cd4..903f0f7517e0 100644 > --- a/drivers/net/wireless/intel/iwlwifi/fw/api/tx.h > +++ b/drivers/net/wireless/intel/iwlwifi/fw/api/tx.h > @@ -222,34 +222,37 @@ enum iwl_tx_offload_assist_flags_pos { > * and then the actial payload. > */ > struct iwl_tx_cmd { > - __le16 len; > - __le16 offload_assist; > - __le32 tx_flags; > - struct { > - u8 try_cnt; > - u8 btkill_cnt; > - __le16 reserved; > - } scratch; /* DRAM_SCRATCH_API_U_VER_1 */ > - __le32 rate_n_flags; > - u8 sta_id; > - u8 sec_ctl; > - u8 initial_rate_index; > - u8 reserved2; > - u8 key[16]; > - __le32 reserved3; > - __le32 life_time; > - __le32 dram_lsb_ptr; > - u8 dram_msb_ptr; > - u8 rts_retry_limit; > - u8 data_retry_limit; > - u8 tid_tspec; > - __le16 pm_frame_timeout; > - __le16 reserved4; > - union { > - DECLARE_FLEX_ARRAY(u8, payload); > - DECLARE_FLEX_ARRAY(struct ieee80211_hdr, hdr); > - }; > + /* New members MUST be added within the __struct_group() macro below. */ > + __struct_group(iwl_tx_cmd_hdr, __hdr, __packed, > + __le16 len; > + __le16 offload_assist; > + __le32 tx_flags; > + struct { > + u8 try_cnt; > + u8 btkill_cnt; > + __le16 reserved; > + } scratch; /* DRAM_SCRATCH_API_U_VER_1 */ > + __le32 rate_n_flags; > + u8 sta_id; > + u8 sec_ctl; > + u8 initial_rate_index; > + u8 reserved2; > + u8 key[16]; > + __le32 reserved3; > + __le32 life_time; > + __le32 dram_lsb_ptr; > + u8 dram_msb_ptr; > + u8 rts_retry_limit; > + u8 data_retry_limit; > + u8 tid_tspec; > + __le16 pm_frame_timeout; > + __le16 reserved4; > + ); > + > + struct ieee80211_hdr hdr[]; > } __packed; /* TX_CMD_API_S_VER_6 */ > +static_assert(offsetof(struct iwl_tx_cmd, hdr) == sizeof(struct iwl_tx_cmd_hdr), > + "struct member likely outside of __struct_group()"); > > struct iwl_dram_sec_info { > __le32 pn_low; > @@ -742,7 +745,7 @@ struct iwl_mvm_compressed_ba_notif { > * @frame: the template of the beacon frame > */ > struct iwl_mac_beacon_cmd_v6 { > - struct iwl_tx_cmd tx; > + struct iwl_tx_cmd_hdr tx; > __le32 template_id; > __le32 tim_idx; > __le32 tim_size; > @@ -761,7 +764,7 @@ struct iwl_mac_beacon_cmd_v6 { > * @frame: the template of the beacon frame > */ > struct iwl_mac_beacon_cmd_v7 { > - struct iwl_tx_cmd tx; > + struct iwl_tx_cmd_hdr tx; > __le32 template_id; > __le32 tim_idx; > __le32 tim_size; > diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c b/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c > index dfcc96f18b4f..41e276f2fcf8 100644 > --- a/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c > +++ b/drivers/net/wireless/intel/iwlwifi/mvm/mac-ctxt.c > @@ -1053,8 +1053,10 @@ static int iwl_mvm_mac_ctxt_send_beacon_v6(struct iwl_mvm *mvm, > { > struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif); > struct iwl_mac_beacon_cmd_v6 beacon_cmd = {}; > + struct iwl_tx_cmd *beacon_cmd_tx = > + container_of(&beacon_cmd.tx, struct iwl_tx_cmd, __hdr); > > - iwl_mvm_mac_ctxt_set_tx(mvm, vif, beacon, &beacon_cmd.tx); > + iwl_mvm_mac_ctxt_set_tx(mvm, vif, beacon, beacon_cmd_tx); > > beacon_cmd.template_id = cpu_to_le32((u32)mvmvif->id); > > @@ -1073,8 +1075,10 @@ static int iwl_mvm_mac_ctxt_send_beacon_v7(struct iwl_mvm *mvm, > { > struct iwl_mvm_vif *mvmvif = iwl_mvm_vif_from_mac80211(vif); > struct iwl_mac_beacon_cmd_v7 beacon_cmd = {}; > + struct iwl_tx_cmd *beacon_cmd_tx = > + container_of(&beacon_cmd.tx, struct iwl_tx_cmd, __hdr); > > - iwl_mvm_mac_ctxt_set_tx(mvm, vif, beacon, &beacon_cmd.tx); > + iwl_mvm_mac_ctxt_set_tx(mvm, vif, beacon, beacon_cmd_tx); > > beacon_cmd.template_id = cpu_to_le32((u32)mvmvif->id); > > diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/tdls.c b/drivers/net/wireless/intel/iwlwifi/mvm/tdls.c > index 3d25ff5cd7e8..7e45445c3ce6 100644 > --- a/drivers/net/wireless/intel/iwlwifi/mvm/tdls.c > +++ b/drivers/net/wireless/intel/iwlwifi/mvm/tdls.c > @@ -341,6 +341,8 @@ iwl_mvm_tdls_config_channel_switch(struct iwl_mvm *mvm, > struct iwl_tdls_channel_switch_cmd cmd = {0}; > struct iwl_tdls_channel_switch_cmd_tail *tail = > iwl_mvm_chan_info_cmd_tail(mvm, &cmd.ci); > + struct iwl_tx_cmd *tail_frame_tx_cmd = > + container_of(&tail->frame.tx_cmd, struct iwl_tx_cmd, __hdr); > u16 len = sizeof(cmd) - iwl_mvm_chan_info_padding(mvm); > int ret; > > @@ -410,13 +412,13 @@ iwl_mvm_tdls_config_channel_switch(struct iwl_mvm *mvm, > ret = -EINVAL; > goto out; > } > - iwl_mvm_set_tx_cmd_ccmp(info, &tail->frame.tx_cmd); > + iwl_mvm_set_tx_cmd_ccmp(info, tail_frame_tx_cmd); > } > > - iwl_mvm_set_tx_cmd(mvm, skb, &tail->frame.tx_cmd, info, > + iwl_mvm_set_tx_cmd(mvm, skb, tail_frame_tx_cmd, info, > mvmsta->deflink.sta_id); > > - iwl_mvm_set_tx_cmd_rate(mvm, &tail->frame.tx_cmd, info, sta, > + iwl_mvm_set_tx_cmd_rate(mvm, tail_frame_tx_cmd, info, sta, > hdr->frame_control); > rcu_read_unlock(); >
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