treewide: Replace open-coded flex array unions

Many places in the kernel try to have an effective union of typed trailing
flexible arrays, but since the C standard doesn't like this, such structs
stack a zero-element array with a flexible array. This will cause problems
with size checks against such zero-element arrays, so they must all be
converted to "real" flexible array unions using the new helper.

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: "Gustavo A. R. Silva" <gustavoars@kernel.org>
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: bpf@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>

8 files changed, 41 insertions, 21 deletions

diff --git a/drivers/crypto/chelsio/chcr_crypto.h b/drivers/crypto/chelsio/chcr_crypto.h
index e89f9e0094b40..332ea73aab898 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[];
+	flex_array_union(
+		struct chcr_gcm_ctx gcm[],
+		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[];
+	flex_array_union3(
+		struct hmac_ctx hmacctx[],
+		struct ablk_ctx ablkctx[],
+		struct chcr_aead_ctx aeadctx[]
+	);
 };
 
 struct chcr_context {
diff --git a/drivers/net/wireless/ath/ath10k/htt.h b/drivers/net/wireless/ath/ath10k/htt.h
index ec689e3ce48a7..2b67f2c2a4311 100644
--- a/drivers/net/wireless/ath/ath10k/htt.h
+++ b/drivers/net/wireless/ath/ath10k/htt.h
@@ -1674,8 +1674,10 @@ 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[];
+	flex_array_union(
+		__le32 resp_ids[], /* ath10k_htt_get_tx_fetch_ind_resp_ids() */
+		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..7a4fdf9d2ffe4 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[];
+	flex_array_union(
+		u8 payload[],
+		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..ee556fb780620 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[];
+	flex_array_union(
+		u8 payload[],
+		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..f897ad7a9878e 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[];
+	flex_array_union(
+		struct iwl_mvm_compressed_ba_ratid ra_tid[],
+		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..19ec17de66802 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[];
+	flex_array_union(
+		struct asd_ms_conn_desc conn_desc[],
+		struct asd_ms_node_desc node_desc[]
+	);
 } __attribute__ ((packed));
 
 struct asd_ctrla_phy_entry {
diff --git a/include/linux/filter.h b/include/linux/filter.h
index ff698c9d1c946..21e32f04f5df1 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[];
+	flex_array_union(
+		struct sock_filter	insns[],
+		struct bpf_insn		insnsi[]
+	);
 };
 
 struct sk_filter {
diff --git a/include/scsi/sas.h b/include/scsi/sas.h
index 4726c1bbec659..4e99335e3685a 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[];
+	flex_array_union(
+		u8     resp_data[],
+		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[];
+	flex_array_union(
+		u8     resp_data[],
+		u8     sense_data[]
+	);
 } __attribute__ ((packed));
 
 struct ssp_command_iu {