[PATCH] ath11k: Replace zero-length array with flexible-array
From: Gustavo A. R. Silva
Date: Mon May 04 2020 - 16:28:40 EST
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 <gustavo@xxxxxxxxxxxxxx>
---
drivers/net/wireless/ath/ath11k/debug.h | 4 ++--
drivers/net/wireless/ath/ath11k/debug_htt_stats.h | 8 ++++----
drivers/net/wireless/ath/ath11k/hal_desc.h | 4 ++--
drivers/net/wireless/ath/ath11k/hal_rx.h | 2 +-
drivers/net/wireless/ath/ath11k/hw.h | 2 +-
drivers/net/wireless/ath/ath11k/wmi.h | 2 +-
6 files changed, 11 insertions(+), 11 deletions(-)
diff --git a/drivers/net/wireless/ath/ath11k/debug.h b/drivers/net/wireless/ath/ath11k/debug.h
index 97e7306c506d..c7edf946ff5c 100644
--- a/drivers/net/wireless/ath/ath11k/debug.h
+++ b/drivers/net/wireless/ath/ath11k/debug.h
@@ -67,7 +67,7 @@ struct debug_htt_stats_req {
u8 peer_addr[ETH_ALEN];
struct completion cmpln;
u32 buf_len;
- u8 buf[0];
+ u8 buf[];
};
struct ath_pktlog_hdr {
@@ -77,7 +77,7 @@ struct ath_pktlog_hdr {
u16 size;
u32 timestamp;
u32 type_specific_data;
- u8 payload[0];
+ u8 payload[];
};
#define ATH11K_HTT_STATS_BUF_SIZE (1024 * 512)
diff --git a/drivers/net/wireless/ath/ath11k/debug_htt_stats.h b/drivers/net/wireless/ath/ath11k/debug_htt_stats.h
index 23a6baa9e95a..682a6ff222bd 100644
--- a/drivers/net/wireless/ath/ath11k/debug_htt_stats.h
+++ b/drivers/net/wireless/ath/ath11k/debug_htt_stats.h
@@ -239,7 +239,7 @@ struct htt_tx_pdev_stats_tx_ppdu_stats_tlv_v {
*/
struct htt_tx_pdev_stats_tried_mpdu_cnt_hist_tlv_v {
u32 hist_bin_size;
- u32 tried_mpdu_cnt_hist[0]; /* HTT_TX_PDEV_TRIED_MPDU_CNT_HIST */
+ u32 tried_mpdu_cnt_hist[]; /* HTT_TX_PDEV_TRIED_MPDU_CNT_HIST */
};
/* == SOC ERROR STATS == */
@@ -550,7 +550,7 @@ struct htt_tx_hwq_stats_cmn_tlv {
struct htt_tx_hwq_difs_latency_stats_tlv_v {
u32 hist_intvl;
/* histogram of ppdu post to hwsch - > cmd status received */
- u32 difs_latency_hist[0]; /* HTT_TX_HWQ_MAX_DIFS_LATENCY_BINS */
+ u32 difs_latency_hist[]; /* HTT_TX_HWQ_MAX_DIFS_LATENCY_BINS */
};
/* NOTE: Variable length TLV, use length spec to infer array size */
@@ -586,7 +586,7 @@ struct htt_tx_hwq_fes_result_stats_tlv_v {
struct htt_tx_hwq_tried_mpdu_cnt_hist_tlv_v {
u32 hist_bin_size;
/* Histogram of number of mpdus on tried mpdu */
- u32 tried_mpdu_cnt_hist[0]; /* HTT_TX_HWQ_TRIED_MPDU_CNT_HIST */
+ u32 tried_mpdu_cnt_hist[]; /* HTT_TX_HWQ_TRIED_MPDU_CNT_HIST */
};
/* NOTE: Variable length TLV, use length spec to infer array size
@@ -1584,7 +1584,7 @@ struct htt_pdev_stats_twt_session_tlv {
struct htt_pdev_stats_twt_sessions_tlv {
u32 pdev_id;
u32 num_sessions;
- struct htt_pdev_stats_twt_session_tlv twt_session[0];
+ struct htt_pdev_stats_twt_session_tlv twt_session[];
};
enum htt_rx_reo_resource_sample_id_enum {
diff --git a/drivers/net/wireless/ath/ath11k/hal_desc.h b/drivers/net/wireless/ath/ath11k/hal_desc.h
index 5e200380cca4..a1f747c1c44d 100644
--- a/drivers/net/wireless/ath/ath11k/hal_desc.h
+++ b/drivers/net/wireless/ath/ath11k/hal_desc.h
@@ -477,7 +477,7 @@ enum hal_tlv_tag {
struct hal_tlv_hdr {
u32 tl;
- u8 value[0];
+ u8 value[];
} __packed;
#define RX_MPDU_DESC_INFO0_MSDU_COUNT GENMASK(7, 0)
@@ -1972,7 +1972,7 @@ struct hal_rx_reo_queue {
u32 processed_total_bytes;
u32 info5;
u32 rsvd[3];
- struct hal_rx_reo_queue_ext ext_desc[0];
+ struct hal_rx_reo_queue_ext ext_desc[];
} __packed;
/* hal_rx_reo_queue
diff --git a/drivers/net/wireless/ath/ath11k/hal_rx.h b/drivers/net/wireless/ath/ath11k/hal_rx.h
index e863e4abfcc1..c436191ae1e8 100644
--- a/drivers/net/wireless/ath/ath11k/hal_rx.h
+++ b/drivers/net/wireless/ath/ath11k/hal_rx.h
@@ -23,7 +23,7 @@ struct hal_rx_wbm_rel_info {
struct hal_rx_mon_status_tlv_hdr {
u32 hdr;
- u8 value[0];
+ u8 value[];
};
enum hal_rx_su_mu_coding {
diff --git a/drivers/net/wireless/ath/ath11k/hw.h b/drivers/net/wireless/ath/ath11k/hw.h
index 9973477ae373..cdec95644758 100644
--- a/drivers/net/wireless/ath/ath11k/hw.h
+++ b/drivers/net/wireless/ath/ath11k/hw.h
@@ -111,7 +111,7 @@ struct ath11k_hw_params {
struct ath11k_fw_ie {
__le32 id;
__le32 len;
- u8 data[0];
+ u8 data[];
};
enum ath11k_bd_ie_board_type {
diff --git a/drivers/net/wireless/ath/ath11k/wmi.h b/drivers/net/wireless/ath/ath11k/wmi.h
index 510f9c6bc1d7..717e87db91cb 100644
--- a/drivers/net/wireless/ath/ath11k/wmi.h
+++ b/drivers/net/wireless/ath/ath11k/wmi.h
@@ -39,7 +39,7 @@ struct wmi_cmd_hdr {
struct wmi_tlv {
u32 header;
- u8 value[0];
+ u8 value[];
} __packed;
#define WMI_TLV_LEN GENMASK(15, 0)
--
2.26.2