[PATCH 2/4] wifi: ath12k: hal_rx: Use memset_startat() for clearing queue descriptors

[Thiraviyam Mariyappan]

In preparation for FORTIFY_SOURCE performing compile-time and run-time
field bounds checking for memset(), avoid intentionally writing across
neighboring fields.

Use memset_startat() so memset() doesn't get confused about writing
beyond the destination member that is intended to be the starting point
of zeroing through the end of the struct and fixes the below clang
warning.

Warning:
include/linux/fortify-string.h:314:4: warning: call to '__write_overflow_field' declared with 'warning' attribute:
detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribute-warning]

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.0-03171-QCAHKSWPL_SILICONZ-1
Reported-by: kernel test robot <lkp at intel.com>
Signed-off-by: Thiraviyam Mariyappan <quic_tmariyap at quicinc.com>
---
 drivers/net/wireless/ath/ath12k/hal_rx.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/ath/ath12k/hal_rx.c b/drivers/net/wireless/ath/ath12k/hal_rx.c
index d47befb83e38..ee61a6462fdc 100644
--- a/drivers/net/wireless/ath/ath12k/hal_rx.c
+++ b/drivers/net/wireless/ath/ath12k/hal_rx.c
@@ -30,8 +30,7 @@ static int ath12k_hal_reo_cmd_queue_stats(struct hal_tlv_64_hdr *tlv,
 		  u32_encode_bits(sizeof(*desc), HAL_TLV_HDR_LEN);
 
 	desc = (struct hal_reo_get_queue_stats *)tlv->value;
-	memset(&desc->queue_addr_lo, 0,
-	       (sizeof(*desc) - sizeof(struct hal_reo_cmd_hdr)));
+	memset_startat(desc, 0, queue_addr_lo);
 
 	desc->cmd.info0 &= ~cpu_to_le32(HAL_REO_CMD_HDR_INFO0_STATUS_REQUIRED);
 	if (cmd->flag & HAL_REO_CMD_FLG_NEED_STATUS)
@@ -64,8 +63,7 @@ static int ath12k_hal_reo_cmd_flush_cache(struct ath12k_hal *hal,
 		  u32_encode_bits(sizeof(*desc), HAL_TLV_HDR_LEN);
 
 	desc = (struct hal_reo_flush_cache *)tlv->value;
-	memset(&desc->cache_addr_lo, 0,
-	       (sizeof(*desc) - sizeof(struct hal_reo_cmd_hdr)));
+	memset_startat(desc, 0, cache_addr_lo);
 
 	desc->cmd.info0 &= ~cpu_to_le32(HAL_REO_CMD_HDR_INFO0_STATUS_REQUIRED);
 	if (cmd->flag & HAL_REO_CMD_FLG_NEED_STATUS)
@@ -103,8 +101,7 @@ static int ath12k_hal_reo_cmd_update_rx_queue(struct hal_tlv_64_hdr *tlv,
 		  u32_encode_bits(sizeof(*desc), HAL_TLV_HDR_LEN);
 
 	desc = (struct hal_reo_update_rx_queue *)tlv->value;
-	memset(&desc->queue_addr_lo, 0,
-	       (sizeof(*desc) - sizeof(struct hal_reo_cmd_hdr)));
+	memset_startat(desc, 0, queue_addr_lo);
 
 	desc->cmd.info0 &= ~cpu_to_le32(HAL_REO_CMD_HDR_INFO0_STATUS_REQUIRED);
 	if (cmd->flag & HAL_REO_CMD_FLG_NEED_STATUS)
-- 
2.17.1