From patchwork Tue Feb 25 01:18:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Gustavo A. R. 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R. Silva" To: Christian Lamparter , Kalle Valo , "David S. Miller" Cc: linux-wireless@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, "Gustavo A. R. Silva" Subject: [PATCH][next] p54: Replace zero-length array with flexible-array member Message-ID: <20200225011846.GA2773@embeddedor> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - gator4166.hostgator.com X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - embeddedor.com X-BWhitelist: no X-Source-IP: 201.166.191.27 X-Source-L: No X-Exim-ID: 1j6OpI-002uUc-U7 X-Source: X-Source-Args: X-Source-Dir: X-Source-Sender: (embeddedor) [201.166.191.27]:58584 X-Source-Auth: gustavo@embeddedor.com X-Email-Count: 21 X-Source-Cap: Z3V6aWRpbmU7Z3V6aWRpbmU7Z2F0b3I0MTY2Lmhvc3RnYXRvci5jb20= X-Local-Domain: yes Sender: linux-wireless-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-wireless@vger.kernel.org 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] 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 --- drivers/net/wireless/intersil/p54/eeprom.h | 8 ++++---- drivers/net/wireless/intersil/p54/lmac.h | 6 +++--- drivers/net/wireless/intersil/p54/p54.h | 2 +- 3 files changed, 8 insertions(+), 8 deletions(-) diff --git a/drivers/net/wireless/intersil/p54/eeprom.h b/drivers/net/wireless/intersil/p54/eeprom.h index b8f46883a292..1d0aaf54389a 100644 --- a/drivers/net/wireless/intersil/p54/eeprom.h +++ b/drivers/net/wireless/intersil/p54/eeprom.h @@ -24,7 +24,7 @@ struct pda_entry { __le16 len; /* includes both code and data */ __le16 code; - u8 data[0]; + u8 data[]; } __packed; struct eeprom_pda_wrap { @@ -32,7 +32,7 @@ struct eeprom_pda_wrap { __le16 pad; __le16 len; __le32 arm_opcode; - u8 data[0]; + u8 data[]; } __packed; struct p54_iq_autocal_entry { @@ -87,7 +87,7 @@ struct pda_pa_curve_data { u8 channels; u8 points_per_channel; u8 padding; - u8 data[0]; + u8 data[]; } __packed; struct pda_rssi_cal_ext_entry { @@ -119,7 +119,7 @@ struct pda_custom_wrapper { __le16 entry_size; __le16 offset; __le16 len; - u8 data[0]; + u8 data[]; } __packed; /* diff --git a/drivers/net/wireless/intersil/p54/lmac.h b/drivers/net/wireless/intersil/p54/lmac.h index e00761536cfc..8adde6ba35ab 100644 --- a/drivers/net/wireless/intersil/p54/lmac.h +++ b/drivers/net/wireless/intersil/p54/lmac.h @@ -81,7 +81,7 @@ struct p54_hdr { __le16 type; /* enum p54_control_frame_types */ u8 rts_tries; u8 tries; - u8 data[0]; + u8 data[]; } __packed; #define GET_REQ_ID(skb) \ @@ -176,7 +176,7 @@ struct p54_rx_data { u8 rssi_raw; __le32 tsf32; __le32 unalloc0; - u8 align[0]; + u8 align[]; } __packed; enum p54_trap_type { @@ -267,7 +267,7 @@ struct p54_tx_data { } __packed normal; } __packed; u8 unalloc2[2]; - u8 align[0]; + u8 align[]; } __packed; /* unit is ms */ diff --git a/drivers/net/wireless/intersil/p54/p54.h b/drivers/net/wireless/intersil/p54/p54.h index 0a9c1a19380f..3356ea708d81 100644 --- a/drivers/net/wireless/intersil/p54/p54.h +++ b/drivers/net/wireless/intersil/p54/p54.h @@ -126,7 +126,7 @@ struct p54_cal_database { size_t entry_size; size_t offset; size_t len; - u8 data[0]; + u8 data[]; }; #define EEPROM_READBACK_LEN 0x3fc