treewide: Replace open-coded flex arrays in unions

In support of enabling -Warray-bounds and -Wzero-length-bounds and
correctly handling run-time memcpy() bounds checking, replace all
open-coded flexible arrays (i.e. 0-element arrays) in unions with the
flex_array() helper macro.

This fixes warnings such as:

fs/hpfs/anode.c: In function 'hpfs_add_sector_to_btree':
fs/hpfs/anode.c:209:27: warning: array subscript 0 is outside the bounds of an interior zero-length array 'struct bplus_internal_node[0]' [-Wzero-length-bounds]
  209 |    anode->btree.u.internal[0].down = cpu_to_le32(a);
      |    ~~~~~~~~~~~~~~~~~~~~~~~^~~
In file included from fs/hpfs/hpfs_fn.h:26,
                 from fs/hpfs/anode.c:10:
fs/hpfs/hpfs.h:412:32: note: while referencing 'internal'
  412 |     struct bplus_internal_node internal[0]; /* (internal) 2-word entries giving
      |                                ^~~~~~~~

drivers/net/can/usb/etas_es58x/es58x_fd.c: In function 'es58x_fd_tx_can_msg':
drivers/net/can/usb/etas_es58x/es58x_fd.c:360:35: warning: array subscript 65535 is outside the bounds of an interior zero-length array 'u8[0]' {aka 'unsigned char[]'} [-Wzero-length-bounds]
  360 |  tx_can_msg = (typeof(tx_can_msg))&es58x_fd_urb_cmd->raw_msg[msg_len];
      |                                   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from drivers/net/can/usb/etas_es58x/es58x_core.h:22,
                 from drivers/net/can/usb/etas_es58x/es58x_fd.c:17:
drivers/net/can/usb/etas_es58x/es58x_fd.h:231:6: note: while referencing 'raw_msg'
  231 |   u8 raw_msg[0];
      |      ^~~~~~~

Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Ayush Sawal <ayush.sawal@chelsio.com>
Cc: Vinay Kumar Yadav <vinay.yadav@chelsio.com>
Cc: Rohit Maheshwari <rohitm@chelsio.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Stanislaw Gruszka <stf_xl@wp.pl>
Cc: Luca Coelho <luciano.coelho@intel.com>
Cc: "James E.J. Bottomley" <jejb@linux.ibm.com>
Cc: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Song Liu <songliubraving@fb.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@kernel.org>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Mordechay Goodstein <mordechay.goodstein@intel.com>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Arunachalam Santhanam <arunachalam.santhanam@in.bosch.com>
Cc: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Cc: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz>
Cc: linux-crypto@vger.kernel.org
Cc: ath10k@lists.infradead.org
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: linux-can@vger.kernel.org
Cc: bpf@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

13 files changed, 56 insertions, 31 deletions

diff --git a/drivers/crypto/chelsio/chcr_crypto.h b/drivers/crypto/chelsio/chcr_crypto.h
index e89f9e0094b40..1cadc231c6b01 100644
--- a/drivers/crypto/chelsio/chcr_crypto.h
+++ b/drivers/crypto/chelsio/chcr_crypto.h
@@ -222,8 +222,10 @@ struct chcr_authenc_ctx {
 };
 
 struct __aead_ctx {
-	struct chcr_gcm_ctx gcm[0];
-	struct chcr_authenc_ctx authenc[];
+	union {
+		flex_array(struct chcr_gcm_ctx gcm[]);
+		flex_array(struct chcr_authenc_ctx authenc[]);
+	};
 };
 
 struct chcr_aead_ctx {
@@ -245,9 +247,11 @@ struct hmac_ctx {
 };
 
 struct __crypto_ctx {
-	struct hmac_ctx hmacctx[0];
-	struct ablk_ctx ablkctx[0];
-	struct chcr_aead_ctx aeadctx[];
+	union {
+		flex_array(struct hmac_ctx hmacctx[]);
+		flex_array(struct ablk_ctx ablkctx[]);
+		flex_array(struct chcr_aead_ctx aeadctx[]);
+	};
 };
 
 struct chcr_context {
diff --git a/drivers/net/can/usb/etas_es58x/es581_4.h b/drivers/net/can/usb/etas_es58x/es581_4.h
index 4bc60a6df697d..8657145dc2a92 100644
--- a/drivers/net/can/usb/etas_es58x/es581_4.h
+++ b/drivers/net/can/usb/etas_es58x/es581_4.h
@@ -192,7 +192,7 @@ struct es581_4_urb_cmd {
 		struct es581_4_rx_cmd_ret rx_cmd_ret;
 		__le64 timestamp;
 		u8 rx_cmd_ret_u8;
-		u8 raw_msg[0];
+		flex_array(u8 raw_msg);
 	} __packed;
 
 	__le16 reserved_for_crc16_do_not_use;
diff --git a/drivers/net/can/usb/etas_es58x/es58x_fd.h b/drivers/net/can/usb/etas_es58x/es58x_fd.h
index ee18a87e40c00..3053e09581329 100644
--- a/drivers/net/can/usb/etas_es58x/es58x_fd.h
+++ b/drivers/net/can/usb/etas_es58x/es58x_fd.h
@@ -228,7 +228,7 @@ struct es58x_fd_urb_cmd {
 		struct es58x_fd_tx_ack_msg tx_ack_msg;
 		__le64 timestamp;
 		__le32 rx_cmd_ret_le32;
-		u8 raw_msg[0];
+		flex_array(u8 raw_msg[]);
 	} __packed;
 
 	__le16 reserved_for_crc16_do_not_use;
diff --git a/drivers/net/wireless/ath/ath10k/htt.h b/drivers/net/wireless/ath/ath10k/htt.h
index ec689e3ce48a7..c0729f8825564 100644
--- a/drivers/net/wireless/ath/ath10k/htt.h
+++ b/drivers/net/wireless/ath/ath10k/htt.h
@@ -1674,8 +1674,11 @@ struct htt_tx_fetch_ind {
 	__le32 token;
 	__le16 num_resp_ids;
 	__le16 num_records;
-	__le32 resp_ids[0]; /* ath10k_htt_get_tx_fetch_ind_resp_ids() */
-	struct htt_tx_fetch_record records[];
+	union {
+		/* ath10k_htt_get_tx_fetch_ind_resp_ids() */
+		flex_array(__le32 resp_ids[]);
+		flex_array(struct htt_tx_fetch_record records[]);
+	};
 } __packed;
 
 static inline void *
diff --git a/drivers/net/wireless/intel/iwlegacy/commands.h b/drivers/net/wireless/intel/iwlegacy/commands.h
index 89c6671b32bcb..ec0bc534c503c 100644
--- a/drivers/net/wireless/intel/iwlegacy/commands.h
+++ b/drivers/net/wireless/intel/iwlegacy/commands.h
@@ -1408,8 +1408,10 @@ struct il3945_tx_cmd {
 	 * MAC header goes here, followed by 2 bytes padding if MAC header
 	 * length is 26 or 30 bytes, followed by payload data
 	 */
-	u8 payload[0];
-	struct ieee80211_hdr hdr[];
+	union {
+		flex_array(u8 payload[]);
+		flex_array(struct ieee80211_hdr hdr[]);
+	};
 } __packed;
 
 /*
diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/commands.h b/drivers/net/wireless/intel/iwlwifi/dvm/commands.h
index 235c7a2e3483f..efe205929a217 100644
--- a/drivers/net/wireless/intel/iwlwifi/dvm/commands.h
+++ b/drivers/net/wireless/intel/iwlwifi/dvm/commands.h
@@ -1251,8 +1251,10 @@ struct iwl_tx_cmd {
 	 * MAC header goes here, followed by 2 bytes padding if MAC header
 	 * length is 26 or 30 bytes, followed by payload data
 	 */
-	u8 payload[0];
-	struct ieee80211_hdr hdr[];
+	union {
+		flex_array(u8 payload[]);
+		flex_array(struct ieee80211_hdr hdr[]);
+	};
 } __packed;
 
 /*
diff --git a/drivers/net/wireless/intel/iwlwifi/fw/api/tx.h b/drivers/net/wireless/intel/iwlwifi/fw/api/tx.h
index 24e4a82a55da1..d183f4856220d 100644
--- a/drivers/net/wireless/intel/iwlwifi/fw/api/tx.h
+++ b/drivers/net/wireless/intel/iwlwifi/fw/api/tx.h
@@ -713,8 +713,10 @@ struct iwl_mvm_compressed_ba_notif {
 	__le32 tx_rate;
 	__le16 tfd_cnt;
 	__le16 ra_tid_cnt;
-	struct iwl_mvm_compressed_ba_ratid ra_tid[0];
-	struct iwl_mvm_compressed_ba_tfd tfd[];
+	union {
+		flex_array(struct iwl_mvm_compressed_ba_ratid ra_tid[]);
+		flex_array(struct iwl_mvm_compressed_ba_tfd tfd[]);
+	};
 } __packed; /* COMPRESSED_BA_RES_API_S_VER_4 */
 
 /**
diff --git a/drivers/scsi/aic94xx/aic94xx_sds.c b/drivers/scsi/aic94xx/aic94xx_sds.c
index 46815e65f7a45..ae20b855d449e 100644
--- a/drivers/scsi/aic94xx/aic94xx_sds.c
+++ b/drivers/scsi/aic94xx/aic94xx_sds.c
@@ -517,8 +517,10 @@ struct asd_ms_conn_map {
 	u8    num_nodes;
 	u8    usage_model_id;
 	u32   _resvd;
-	struct asd_ms_conn_desc conn_desc[0];
-	struct asd_ms_node_desc node_desc[];
+	union {
+		flex_array(struct asd_ms_conn_desc conn_desc[]);
+		flex_array(struct asd_ms_node_desc node_desc[]);
+	};
 } __attribute__ ((packed));
 
 struct asd_ctrla_phy_entry {
diff --git a/fs/hpfs/hpfs.h b/fs/hpfs/hpfs.h
index d92c4af3e1b43..ee26c85d57a7b 100644
--- a/fs/hpfs/hpfs.h
+++ b/fs/hpfs/hpfs.h
@@ -409,10 +409,10 @@ struct bplus_header
   __le16 first_free;			/* offset from start of header to
 					   first free node in array */
   union {
-    struct bplus_internal_node internal[0]; /* (internal) 2-word entries giving
-					       subtree pointers */
-    struct bplus_leaf_node external[0];	    /* (external) 3-word entries giving
-					       sector runs */
+	/* (internal) 2-word entries giving subtree pointers */
+	flex_array(struct bplus_internal_node internal[]);
+	/* (external) 3-word entries giving sector runs */
+	flex_array(struct bplus_leaf_node external[]);
   } u;
 };
 
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 1797e8506929d..6c41c03b791ce 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -588,8 +588,10 @@ struct bpf_prog {
 	struct bpf_prog_aux	*aux;		/* Auxiliary fields */
 	struct sock_fprog_kern	*orig_prog;	/* Original BPF program */
 	/* Instructions for interpreter */
-	struct sock_filter	insns[0];
-	struct bpf_insn		insnsi[];
+	union {
+		flex_array(struct sock_filter	insns[]);
+		flex_array(struct bpf_insn	insnsi[]);
+	};
 };
 
 struct sk_filter {
diff --git a/include/scsi/sas.h b/include/scsi/sas.h
index 4726c1bbec659..67c63a87602fe 100644
--- a/include/scsi/sas.h
+++ b/include/scsi/sas.h
@@ -323,8 +323,10 @@ struct ssp_response_iu {
 	__be32 sense_data_len;
 	__be32 response_data_len;
 
-	u8     resp_data[0];
-	u8     sense_data[];
+	union {
+		flex_array(u8     resp_data[]);
+		flex_array(u8     sense_data[]);
+	};
 } __attribute__ ((packed));
 
 struct ssp_command_iu {
@@ -554,8 +556,10 @@ struct ssp_response_iu {
 	__be32 sense_data_len;
 	__be32 response_data_len;
 
-	u8     resp_data[0];
-	u8     sense_data[];
+	union {
+		flex_array(u8     resp_data[]);
+		flex_array(u8     sense_data[]);
+	};
 } __attribute__ ((packed));
 
 struct ssp_command_iu {
diff --git a/include/uapi/rdma/rdma_user_rxe.h b/include/uapi/rdma/rdma_user_rxe.h
index e283c2220abaf..fb63de88423be 100644
--- a/include/uapi/rdma/rdma_user_rxe.h
+++ b/include/uapi/rdma/rdma_user_rxe.h
@@ -141,8 +141,10 @@ struct rxe_dma_info {
 	__u32			sge_offset;
 	__u32			reserved;
 	union {
-		__u8		inline_data[0];
-		struct rxe_sge	sge[0];
+		__flex_array(__fa1,
+			     __u8 inline_data[]);
+		__flex_array(__fa2,
+			     struct rxe_sge sge[]);
 	};
 };
 
diff --git a/include/uapi/sound/asoc.h b/include/uapi/sound/asoc.h
index da61398b1f8f3..aa4e9dd94d29c 100644
--- a/include/uapi/sound/asoc.h
+++ b/include/uapi/sound/asoc.h
@@ -240,8 +240,10 @@ struct snd_soc_tplg_vendor_array {
 struct snd_soc_tplg_private {
 	__le32 size;	/* in bytes of private data */
 	union {
-		char data[0];
-		struct snd_soc_tplg_vendor_array array[0];
+		__flex_array(__fa1,
+			     char data[]);
+		__flex_array(__fa2,
+			     struct snd_soc_tplg_vendor_array array[]);
 	};
 } __attribute__((packed));