From da60fbe7ef942d64b4d80e99cc9b0205db5964b9 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Wed, 26 Feb 2020 15:20:00 -0600 Subject: [PATCH] NFC: Replace zero-length array with flexible-array member 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 Signed-off-by: David S. Miller --- drivers/nfc/fdp/fdp.c | 2 +- drivers/nfc/st21nfca/dep.c | 4 ++-- include/net/nfc/nci.h | 14 +++++++------- include/net/nfc/nfc.h | 2 +- 4 files changed, 11 insertions(+), 11 deletions(-) diff --git a/drivers/nfc/fdp/fdp.c b/drivers/nfc/fdp/fdp.c index 0cc9ac856fe2..7c0b1e6b80ff 100644 --- a/drivers/nfc/fdp/fdp.c +++ b/drivers/nfc/fdp/fdp.c @@ -76,7 +76,7 @@ static u8 nci_core_get_config_otp_ram_version[5] = { struct nci_core_get_config_rsp { u8 status; u8 count; - u8 data[0]; + u8 data[]; }; static int fdp_nci_create_conn(struct nci_dev *ndev) diff --git a/drivers/nfc/st21nfca/dep.c b/drivers/nfc/st21nfca/dep.c index 60acdfd1cb8c..a1d69f9b2d4a 100644 --- a/drivers/nfc/st21nfca/dep.c +++ b/drivers/nfc/st21nfca/dep.c @@ -66,7 +66,7 @@ struct st21nfca_atr_req { u8 bsi; u8 bri; u8 ppi; - u8 gbi[0]; + u8 gbi[]; } __packed; struct st21nfca_atr_res { @@ -79,7 +79,7 @@ struct st21nfca_atr_res { u8 bri; u8 to; u8 ppi; - u8 gbi[0]; + u8 gbi[]; } __packed; struct st21nfca_psl_req { diff --git a/include/net/nfc/nci.h b/include/net/nfc/nci.h index 6ab5a83f597c..0550e0380b8d 100644 --- a/include/net/nfc/nci.h +++ b/include/net/nfc/nci.h @@ -244,13 +244,13 @@ struct dest_spec_params { struct core_conn_create_dest_spec_params { __u8 type; __u8 length; - __u8 value[0]; + __u8 value[]; } __packed; struct nci_core_conn_create_cmd { __u8 destination_type; __u8 number_destination_params; - struct core_conn_create_dest_spec_params params[0]; + struct core_conn_create_dest_spec_params params[]; } __packed; #define NCI_OP_CORE_CONN_CLOSE_CMD nci_opcode_pack(NCI_GID_CORE, 0x05) @@ -321,7 +321,7 @@ struct nci_core_init_rsp_1 { __u8 status; __le32 nfcc_features; __u8 num_supported_rf_interfaces; - __u8 supported_rf_interfaces[0]; /* variable size array */ + __u8 supported_rf_interfaces[]; /* variable size array */ /* continuted in nci_core_init_rsp_2 */ } __packed; @@ -338,7 +338,7 @@ struct nci_core_init_rsp_2 { struct nci_core_set_config_rsp { __u8 status; __u8 num_params; - __u8 params_id[0]; /* variable size array */ + __u8 params_id[]; /* variable size array */ } __packed; #define NCI_OP_CORE_CONN_CREATE_RSP nci_opcode_pack(NCI_GID_CORE, 0x04) @@ -501,18 +501,18 @@ struct nci_rf_nfcee_action_ntf { __u8 nfcee_id; __u8 trigger; __u8 supported_data_length; - __u8 supported_data[0]; + __u8 supported_data[]; } __packed; #define NCI_OP_NFCEE_DISCOVER_NTF nci_opcode_pack(NCI_GID_NFCEE_MGMT, 0x00) struct nci_nfcee_supported_protocol { __u8 num_protocol; - __u8 supported_protocol[0]; + __u8 supported_protocol[]; } __packed; struct nci_nfcee_information_tlv { __u8 num_tlv; - __u8 information_tlv[0]; + __u8 information_tlv[]; } __packed; struct nci_nfcee_discover_ntf { diff --git a/include/net/nfc/nfc.h b/include/net/nfc/nfc.h index 5d277d68fd8d..2cd3a261bcbc 100644 --- a/include/net/nfc/nfc.h +++ b/include/net/nfc/nfc.h @@ -146,7 +146,7 @@ struct nfc_evt_transaction { u32 aid_len; u8 aid[NFC_MAX_AID_LENGTH]; u8 params_len; - u8 params[0]; + u8 params[]; } __packed; struct nfc_genl_data { -- 2.20.1