| Message ID | 20200507185538.GA14674@embeddedor (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 45c21a0e5ba461b5fe537ac20d6506f63995ce2d |
| Delegated to: | Luca Coelho |
| Headers | show |
| Series | iwlwifi: Replace zero-length array with flexible-array | expand |
Hi all, Friendly ping: who can take this? Thanks -- Gustavo On Thu, May 07, 2020 at 01:55:38PM -0500, Gustavo A. R. Silva wrote: > The current codebase makes use of the zero-length array language > extension to the C90 standard, but the preferred mechanism to declare > variable-length types such as these ones is a flexible array member[1][2], > introduced in C99: > > struct foo { > int stuff; > struct boo array[]; > }; > > By making use of the mechanism above, we will get a compiler warning > in case the flexible array does not occur last in the structure, which > will help us prevent some kind of undefined behavior bugs from being > inadvertently introduced[3] to the codebase from now on. > > Also, notice that, dynamic memory allocations won't be affected by > this change: > > "Flexible array members have incomplete type, and so the sizeof operator > may not be applied. As a quirk of the original implementation of > zero-length arrays, sizeof evaluates to zero."[1] > > sizeof(flexible-array-member) triggers a warning because flexible array > members have incomplete type[1]. There are some instances of code in > which the sizeof operator is being incorrectly/erroneously applied to > zero-length arrays and the result is zero. Such instances may be hiding > some bugs. So, this work (flexible-array member conversions) will also > help to get completely rid of those sorts of issues. > > This issue was found with the help of Coccinelle. > > [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html > [2] https://github.com/KSPP/linux/issues/21 > [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> > --- > drivers/net/wireless/intel/iwlwifi/dvm/commands.h | 12 ++++++------ > drivers/net/wireless/intel/iwlwifi/fw/api/nvm-reg.h | 4 ++-- > drivers/net/wireless/intel/iwlwifi/fw/debugfs.c | 2 +- > drivers/net/wireless/intel/iwlwifi/iwl-op-mode.h | 2 +- > drivers/net/wireless/intel/iwlwifi/iwl-trans.h | 2 +- > 5 files changed, 11 insertions(+), 11 deletions(-) > > diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/commands.h b/drivers/net/wireless/intel/iwlwifi/dvm/commands.h > index 0f4be4be181c..fdcc1292a92b 100644 > --- a/drivers/net/wireless/intel/iwlwifi/dvm/commands.h > +++ b/drivers/net/wireless/intel/iwlwifi/dvm/commands.h > @@ -1023,7 +1023,7 @@ struct iwl_wep_cmd { > u8 global_key_type; > u8 flags; > u8 reserved; > - struct iwl_wep_key key[0]; > + struct iwl_wep_key key[]; > } __packed; > > #define WEP_KEY_WEP_TYPE 1 > @@ -1305,7 +1305,7 @@ struct iwl_tx_cmd { > * length is 26 or 30 bytes, followed by payload data > */ > u8 payload[0]; > - struct ieee80211_hdr hdr[0]; > + struct ieee80211_hdr hdr[]; > } __packed; > > /* > @@ -2380,7 +2380,7 @@ struct iwl_scan_cmd { > * for one scan to complete (i.e. receive SCAN_COMPLETE_NOTIFICATION) > * before requesting another scan. > */ > - u8 data[0]; > + u8 data[]; > } __packed; > > /* Can abort will notify by complete notification with abort status. */ > @@ -2475,7 +2475,7 @@ struct iwl_tx_beacon_cmd { > __le16 tim_idx; > u8 tim_size; > u8 reserved1; > - struct ieee80211_hdr frame[0]; /* beacon frame */ > + struct ieee80211_hdr frame[]; /* beacon frame */ > } __packed; > > /****************************************************************************** > @@ -3188,7 +3188,7 @@ struct iwl_calib_hdr { > > struct iwl_calib_cmd { > struct iwl_calib_hdr hdr; > - u8 data[0]; > + u8 data[]; > } __packed; > > struct iwl_calib_xtal_freq_cmd { > @@ -3216,7 +3216,7 @@ struct iwl_calib_temperature_offset_v2_cmd { > /* IWL_PHY_CALIBRATE_CHAIN_NOISE_RESET_CMD */ > struct iwl_calib_chain_noise_reset_cmd { > struct iwl_calib_hdr hdr; > - u8 data[0]; > + u8 data[]; > }; > > /* IWL_PHY_CALIBRATE_CHAIN_NOISE_GAIN_CMD */ > diff --git a/drivers/net/wireless/intel/iwlwifi/fw/api/nvm-reg.h b/drivers/net/wireless/intel/iwlwifi/fw/api/nvm-reg.h > index 97b49843e318..397ac89a04c2 100644 > --- a/drivers/net/wireless/intel/iwlwifi/fw/api/nvm-reg.h > +++ b/drivers/net/wireless/intel/iwlwifi/fw/api/nvm-reg.h > @@ -351,7 +351,7 @@ struct iwl_mcc_update_resp_v3 { > __le16 time; > __le16 geo_info; > __le32 n_channels; > - __le32 channels[0]; > + __le32 channels[]; > } __packed; /* LAR_UPDATE_MCC_CMD_RESP_S_VER_3 */ > > /** > @@ -380,7 +380,7 @@ struct iwl_mcc_update_resp { > u8 source_id; > u8 reserved[3]; > __le32 n_channels; > - __le32 channels[0]; > + __le32 channels[]; > } __packed; /* LAR_UPDATE_MCC_CMD_RESP_S_VER_4 */ > > /** > diff --git a/drivers/net/wireless/intel/iwlwifi/fw/debugfs.c b/drivers/net/wireless/intel/iwlwifi/fw/debugfs.c > index 89f74116569d..cc1d93606d9b 100644 > --- a/drivers/net/wireless/intel/iwlwifi/fw/debugfs.c > +++ b/drivers/net/wireless/intel/iwlwifi/fw/debugfs.c > @@ -261,7 +261,7 @@ struct hcmd_write_data { > __be32 cmd_id; > __be32 flags; > __be16 length; > - u8 data[0]; > + u8 data[]; > } __packed; > > static ssize_t iwl_dbgfs_send_hcmd_write(struct iwl_fw_runtime *fwrt, char *buf, > diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-op-mode.h b/drivers/net/wireless/intel/iwlwifi/iwl-op-mode.h > index 3008a5246be8..b35b8920941b 100644 > --- a/drivers/net/wireless/intel/iwlwifi/iwl-op-mode.h > +++ b/drivers/net/wireless/intel/iwlwifi/iwl-op-mode.h > @@ -175,7 +175,7 @@ void iwl_opmode_deregister(const char *name); > struct iwl_op_mode { > const struct iwl_op_mode_ops *ops; > > - char op_mode_specific[0] __aligned(sizeof(void *)); > + char op_mode_specific[] __aligned(sizeof(void *)); > }; > > static inline void iwl_op_mode_stop(struct iwl_op_mode *op_mode) > diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-trans.h b/drivers/net/wireless/intel/iwlwifi/iwl-trans.h > index bba527b339b5..3fbbbac0953d 100644 > --- a/drivers/net/wireless/intel/iwlwifi/iwl-trans.h > +++ b/drivers/net/wireless/intel/iwlwifi/iwl-trans.h > @@ -878,7 +878,7 @@ struct iwl_trans { > > /* pointer to trans specific struct */ > /*Ensure that this pointer will always be aligned to sizeof pointer */ > - char trans_specific[0] __aligned(sizeof(void *)); > + char trans_specific[] __aligned(sizeof(void *)); > }; > > const char *iwl_get_cmd_string(struct iwl_trans *trans, u32 id); >
"Gustavo A. R. Silva" <gustavoars@kernel.org> wrote: > The current codebase makes use of the zero-length array language > extension to the C90 standard, but the preferred mechanism to declare > variable-length types such as these ones is a flexible array member[1][2], > introduced in C99: > > struct foo { > int stuff; > struct boo array[]; > }; > > By making use of the mechanism above, we will get a compiler warning > in case the flexible array does not occur last in the structure, which > will help us prevent some kind of undefined behavior bugs from being > inadvertently introduced[3] to the codebase from now on. > > Also, notice that, dynamic memory allocations won't be affected by > this change: > > "Flexible array members have incomplete type, and so the sizeof operator > may not be applied. As a quirk of the original implementation of > zero-length arrays, sizeof evaluates to zero."[1] > > sizeof(flexible-array-member) triggers a warning because flexible array > members have incomplete type[1]. There are some instances of code in > which the sizeof operator is being incorrectly/erroneously applied to > zero-length arrays and the result is zero. Such instances may be hiding > some bugs. So, this work (flexible-array member conversions) will also > help to get completely rid of those sorts of issues. > > This issue was found with the help of Coccinelle. > > [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html > [2] https://github.com/KSPP/linux/issues/21 > [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") > > Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> Patch applied to iwlwifi-next.git, thanks. 45c21a0e5ba4 iwlwifi: Replace zero-length array with flexible-array
diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/commands.h b/drivers/net/wireless/intel/iwlwifi/dvm/commands.h index 0f4be4be181c..fdcc1292a92b 100644 --- a/drivers/net/wireless/intel/iwlwifi/dvm/commands.h +++ b/drivers/net/wireless/intel/iwlwifi/dvm/commands.h @@ -1023,7 +1023,7 @@ struct iwl_wep_cmd { u8 global_key_type; u8 flags; u8 reserved; - struct iwl_wep_key key[0]; + struct iwl_wep_key key[]; } __packed; #define WEP_KEY_WEP_TYPE 1 @@ -1305,7 +1305,7 @@ struct iwl_tx_cmd { * length is 26 or 30 bytes, followed by payload data */ u8 payload[0]; - struct ieee80211_hdr hdr[0]; + struct ieee80211_hdr hdr[]; } __packed; /* @@ -2380,7 +2380,7 @@ struct iwl_scan_cmd { * for one scan to complete (i.e. receive SCAN_COMPLETE_NOTIFICATION) * before requesting another scan. */ - u8 data[0]; + u8 data[]; } __packed; /* Can abort will notify by complete notification with abort status. */ @@ -2475,7 +2475,7 @@ struct iwl_tx_beacon_cmd { __le16 tim_idx; u8 tim_size; u8 reserved1; - struct ieee80211_hdr frame[0]; /* beacon frame */ + struct ieee80211_hdr frame[]; /* beacon frame */ } __packed; /****************************************************************************** @@ -3188,7 +3188,7 @@ struct iwl_calib_hdr { struct iwl_calib_cmd { struct iwl_calib_hdr hdr; - u8 data[0]; + u8 data[]; } __packed; struct iwl_calib_xtal_freq_cmd { @@ -3216,7 +3216,7 @@ struct iwl_calib_temperature_offset_v2_cmd { /* IWL_PHY_CALIBRATE_CHAIN_NOISE_RESET_CMD */ struct iwl_calib_chain_noise_reset_cmd { struct iwl_calib_hdr hdr; - u8 data[0]; + u8 data[]; }; /* IWL_PHY_CALIBRATE_CHAIN_NOISE_GAIN_CMD */ diff --git a/drivers/net/wireless/intel/iwlwifi/fw/api/nvm-reg.h b/drivers/net/wireless/intel/iwlwifi/fw/api/nvm-reg.h index 97b49843e318..397ac89a04c2 100644 --- a/drivers/net/wireless/intel/iwlwifi/fw/api/nvm-reg.h +++ b/drivers/net/wireless/intel/iwlwifi/fw/api/nvm-reg.h @@ -351,7 +351,7 @@ struct iwl_mcc_update_resp_v3 { __le16 time; __le16 geo_info; __le32 n_channels; - __le32 channels[0]; + __le32 channels[]; } __packed; /* LAR_UPDATE_MCC_CMD_RESP_S_VER_3 */ /** @@ -380,7 +380,7 @@ struct iwl_mcc_update_resp { u8 source_id; u8 reserved[3]; __le32 n_channels; - __le32 channels[0]; + __le32 channels[]; } __packed; /* LAR_UPDATE_MCC_CMD_RESP_S_VER_4 */ /** diff --git a/drivers/net/wireless/intel/iwlwifi/fw/debugfs.c b/drivers/net/wireless/intel/iwlwifi/fw/debugfs.c index 89f74116569d..cc1d93606d9b 100644 --- a/drivers/net/wireless/intel/iwlwifi/fw/debugfs.c +++ b/drivers/net/wireless/intel/iwlwifi/fw/debugfs.c @@ -261,7 +261,7 @@ struct hcmd_write_data { __be32 cmd_id; __be32 flags; __be16 length; - u8 data[0]; + u8 data[]; } __packed; static ssize_t iwl_dbgfs_send_hcmd_write(struct iwl_fw_runtime *fwrt, char *buf, diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-op-mode.h b/drivers/net/wireless/intel/iwlwifi/iwl-op-mode.h index 3008a5246be8..b35b8920941b 100644 --- a/drivers/net/wireless/intel/iwlwifi/iwl-op-mode.h +++ b/drivers/net/wireless/intel/iwlwifi/iwl-op-mode.h @@ -175,7 +175,7 @@ void iwl_opmode_deregister(const char *name); struct iwl_op_mode { const struct iwl_op_mode_ops *ops; - char op_mode_specific[0] __aligned(sizeof(void *)); + char op_mode_specific[] __aligned(sizeof(void *)); }; static inline void iwl_op_mode_stop(struct iwl_op_mode *op_mode) diff --git a/drivers/net/wireless/intel/iwlwifi/iwl-trans.h b/drivers/net/wireless/intel/iwlwifi/iwl-trans.h index bba527b339b5..3fbbbac0953d 100644 --- a/drivers/net/wireless/intel/iwlwifi/iwl-trans.h +++ b/drivers/net/wireless/intel/iwlwifi/iwl-trans.h @@ -878,7 +878,7 @@ struct iwl_trans { /* pointer to trans specific struct */ /*Ensure that this pointer will always be aligned to sizeof pointer */ - char trans_specific[0] __aligned(sizeof(void *)); + char trans_specific[] __aligned(sizeof(void *)); }; const char *iwl_get_cmd_string(struct iwl_trans *trans, u32 id);
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member conversions) will also help to get completely rid of those sorts of issues. This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732932f ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org> --- drivers/net/wireless/intel/iwlwifi/dvm/commands.h | 12 ++++++------ drivers/net/wireless/intel/iwlwifi/fw/api/nvm-reg.h | 4 ++-- drivers/net/wireless/intel/iwlwifi/fw/debugfs.c | 2 +- drivers/net/wireless/intel/iwlwifi/iwl-op-mode.h | 2 +- drivers/net/wireless/intel/iwlwifi/iwl-trans.h | 2 +- 5 files changed, 11 insertions(+), 11 deletions(-)