ath11k: Use memset_startat() for clearing queue descriptors

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. Additionally split up a later
field-spanning memset() so that memset() can reason about the size.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20211118202416.1286046-1-keescook@chromium.org

diff --git a/drivers/net/wireless/ath/ath11k/hal_rx.c b/drivers/net/wireless/ath/ath11k/hal_rx.c
index 329c404cfa80dcb697043113b4df3427f9b26b76..0e43e215c10af0b196e12fc5f2ff27d777812569 100644 (file)
--- a/drivers/net/wireless/ath/ath11k/hal_rx.c
+++ b/drivers/net/wireless/ath/ath11k/hal_rx.c
@@ -29,8 +29,7 @@ static int ath11k_hal_reo_cmd_queue_stats(struct hal_tlv_hdr *tlv,
                  FIELD_PREP(HAL_TLV_HDR_LEN, sizeof(*desc));
 
        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 &= ~HAL_REO_CMD_HDR_INFO0_STATUS_REQUIRED;
        if (cmd->flag & HAL_REO_CMD_FLG_NEED_STATUS)
@@ -62,8 +61,7 @@ static int ath11k_hal_reo_cmd_flush_cache(struct ath11k_hal *hal, struct hal_tlv
                  FIELD_PREP(HAL_TLV_HDR_LEN, sizeof(*desc));
 
        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 &= ~HAL_REO_CMD_HDR_INFO0_STATUS_REQUIRED;
        if (cmd->flag & HAL_REO_CMD_FLG_NEED_STATUS)
@@ -101,8 +99,7 @@ static int ath11k_hal_reo_cmd_update_rx_queue(struct hal_tlv_hdr *tlv,
                  FIELD_PREP(HAL_TLV_HDR_LEN, sizeof(*desc));
 
        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 &= ~HAL_REO_CMD_HDR_INFO0_STATUS_REQUIRED;
        if (cmd->flag & HAL_REO_CMD_FLG_NEED_STATUS)
@@ -764,15 +761,17 @@ void ath11k_hal_reo_qdesc_setup(void *vaddr, int tid, u32 ba_window_size,
         * size changes and also send WMI message to FW to change the REO
         * queue descriptor in Rx peer entry as part of dp_rx_tid_update.
         */
-       memset(ext_desc, 0, 3 * sizeof(*ext_desc));
+       memset(ext_desc, 0, sizeof(*ext_desc));
        ath11k_hal_reo_set_desc_hdr(&ext_desc->desc_hdr, HAL_DESC_REO_OWNED,
                                    HAL_DESC_REO_QUEUE_EXT_DESC,
                                    REO_QUEUE_DESC_MAGIC_DEBUG_PATTERN_1);
        ext_desc++;
+       memset(ext_desc, 0, sizeof(*ext_desc));
        ath11k_hal_reo_set_desc_hdr(&ext_desc->desc_hdr, HAL_DESC_REO_OWNED,
                                    HAL_DESC_REO_QUEUE_EXT_DESC,
                                    REO_QUEUE_DESC_MAGIC_DEBUG_PATTERN_2);
        ext_desc++;
+       memset(ext_desc, 0, sizeof(*ext_desc));
        ath11k_hal_reo_set_desc_hdr(&ext_desc->desc_hdr, HAL_DESC_REO_OWNED,
                                    HAL_DESC_REO_QUEUE_EXT_DESC,
                                    REO_QUEUE_DESC_MAGIC_DEBUG_PATTERN_3);