From 45c21a0e5ba461b5fe537ac20d6506f63995ce2d Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Thu, 7 May 2020 13:55:38 -0500 Subject: iwlwifi: Replace zero-length array with flexible-array 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 Link: https://lore.kernel.org/r/20200507185538.GA14674@embeddedor Signed-off-by: Luca Coelho --- drivers/net/wireless/intel/iwlwifi/dvm/commands.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'drivers/net/wireless/intel/iwlwifi/dvm') 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 */ -- cgit v1.2.3