From e0e05f20c200c41b34294078bbc29d67bfd607ea Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Thu, 7 May 2020 13:54:51 -0500 Subject: [PATCH] ipw2x00: 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 Signed-off-by: Kalle Valo Link: https://lore.kernel.org/r/20200507185451.GA14603@embeddedor --- drivers/net/wireless/intel/ipw2x00/ipw2200.c | 2 +- drivers/net/wireless/intel/ipw2x00/ipw2200.h | 10 +++++----- drivers/net/wireless/intel/ipw2x00/libipw.h | 28 ++++++++++++++-------------- 3 files changed, 20 insertions(+), 20 deletions(-) diff --git a/drivers/net/wireless/intel/ipw2x00/ipw2200.c b/drivers/net/wireless/intel/ipw2x00/ipw2200.c index e9e686a..661e63b 100644 --- a/drivers/net/wireless/intel/ipw2x00/ipw2200.c +++ b/drivers/net/wireless/intel/ipw2x00/ipw2200.c @@ -3386,7 +3386,7 @@ struct ipw_fw { __le32 boot_size; __le32 ucode_size; __le32 fw_size; - u8 data[0]; + u8 data[]; }; static int ipw_get_fw(struct ipw_priv *priv, diff --git a/drivers/net/wireless/intel/ipw2x00/ipw2200.h b/drivers/net/wireless/intel/ipw2x00/ipw2200.h index 4346520..09fa7f1 100644 --- a/drivers/net/wireless/intel/ipw2x00/ipw2200.h +++ b/drivers/net/wireless/intel/ipw2x00/ipw2200.h @@ -448,7 +448,7 @@ struct tfd_command { u8 index; u8 length; __le16 reserved; - u8 payload[0]; + u8 payload[]; } __packed; struct tfd_data { @@ -675,7 +675,7 @@ struct ipw_rx_frame { // is identical) u8 rtscts_seen; // 0x1 RTS seen ; 0x2 CTS seen __le16 length; - u8 data[0]; + u8 data[]; } __packed; struct ipw_rx_header { @@ -1002,7 +1002,7 @@ struct ipw_cmd { /* XXX */ * Incoming parameters listed 1-st, followed by outcoming params. * nParams=(len+3)/4+status_len */ - u32 param[0]; + u32 param[]; } __packed; #define STATUS_HCMD_ACTIVE (1<<0) /**< host command in progress */ @@ -1108,7 +1108,7 @@ struct ipw_fw_error { /* XXX */ u32 log_len; struct ipw_error_elem *elem; struct ipw_event *log; - u8 payload[0]; + u8 payload[]; } __packed; #ifdef CONFIG_IPW2200_PROMISCUOUS @@ -1153,7 +1153,7 @@ struct ipw_rt_hdr { s8 rt_dbmsignal; /* signal in dbM, kluged to signed */ s8 rt_dbmnoise; u8 rt_antenna; /* antenna number */ - u8 payload[0]; /* payload... */ + u8 payload[]; /* payload... */ } __packed; #endif diff --git a/drivers/net/wireless/intel/ipw2x00/libipw.h b/drivers/net/wireless/intel/ipw2x00/libipw.h index e4a6ab4..e87538a 100644 --- a/drivers/net/wireless/intel/ipw2x00/libipw.h +++ b/drivers/net/wireless/intel/ipw2x00/libipw.h @@ -334,7 +334,7 @@ struct libipw_hdr_1addr { __le16 frame_ctl; __le16 duration_id; u8 addr1[ETH_ALEN]; - u8 payload[0]; + u8 payload[]; } __packed; struct libipw_hdr_2addr { @@ -342,7 +342,7 @@ struct libipw_hdr_2addr { __le16 duration_id; u8 addr1[ETH_ALEN]; u8 addr2[ETH_ALEN]; - u8 payload[0]; + u8 payload[]; } __packed; struct libipw_hdr_3addr { @@ -352,7 +352,7 @@ struct libipw_hdr_3addr { u8 addr2[ETH_ALEN]; u8 addr3[ETH_ALEN]; __le16 seq_ctl; - u8 payload[0]; + u8 payload[]; } __packed; struct libipw_hdr_4addr { @@ -363,7 +363,7 @@ struct libipw_hdr_4addr { u8 addr3[ETH_ALEN]; __le16 seq_ctl; u8 addr4[ETH_ALEN]; - u8 payload[0]; + u8 payload[]; } __packed; struct libipw_hdr_3addrqos { @@ -380,7 +380,7 @@ struct libipw_hdr_3addrqos { struct libipw_info_element { u8 id; u8 len; - u8 data[0]; + u8 data[]; } __packed; /* @@ -406,7 +406,7 @@ struct libipw_auth { __le16 transaction; __le16 status; /* challenge */ - struct libipw_info_element info_element[0]; + struct libipw_info_element info_element[]; } __packed; struct libipw_channel_switch { @@ -442,7 +442,7 @@ struct libipw_disassoc { struct libipw_probe_request { struct libipw_hdr_3addr header; /* SSID, supported rates */ - struct libipw_info_element info_element[0]; + struct libipw_info_element info_element[]; } __packed; struct libipw_probe_response { @@ -452,7 +452,7 @@ struct libipw_probe_response { __le16 capability; /* SSID, supported rates, FH params, DS params, * CF params, IBSS params, TIM (if beacon), RSN */ - struct libipw_info_element info_element[0]; + struct libipw_info_element info_element[]; } __packed; /* Alias beacon for probe_response */ @@ -463,7 +463,7 @@ struct libipw_assoc_request { __le16 capability; __le16 listen_interval; /* SSID, supported rates, RSN */ - struct libipw_info_element info_element[0]; + struct libipw_info_element info_element[]; } __packed; struct libipw_reassoc_request { @@ -471,7 +471,7 @@ struct libipw_reassoc_request { __le16 capability; __le16 listen_interval; u8 current_ap[ETH_ALEN]; - struct libipw_info_element info_element[0]; + struct libipw_info_element info_element[]; } __packed; struct libipw_assoc_response { @@ -480,7 +480,7 @@ struct libipw_assoc_response { __le16 status; __le16 aid; /* supported rates */ - struct libipw_info_element info_element[0]; + struct libipw_info_element info_element[]; } __packed; struct libipw_txb { @@ -490,7 +490,7 @@ struct libipw_txb { u8 reserved; u16 frag_size; u16 payload_size; - struct sk_buff *fragments[0]; + struct sk_buff *fragments[]; }; /* SWEEP TABLE ENTRIES NUMBER */ @@ -594,7 +594,7 @@ struct libipw_ibss_dfs { struct libipw_info_element ie; u8 owner[ETH_ALEN]; u8 recovery_interval; - struct libipw_channel_map channel_map[0]; + struct libipw_channel_map channel_map[]; }; struct libipw_csa { @@ -830,7 +830,7 @@ struct libipw_device { /* This must be the last item so that it points to the data * allocated beyond this structure by alloc_libipw */ - u8 priv[0]; + u8 priv[]; }; #define IEEE_A (1<<0) -- 2.7.4