wifi: iwlwifi: calib: Refactor iwl_calib_result usage for clarity

In preparation for FORTIFY_SOURCE performing run-time destination buffer
bounds checking for memcpy(), refactor the use of struct iwl_calib_result:

- Have struct iwl_calib_result contain struct iwl_calib_cmd since
  functions expect to operate on the "data" flex array in "cmd", which
  follows the "hdr" member.
- Switch argument passing around to use struct iwl_calib_cmd instead of
  struct iwl_calib_hdr to prepare functions to see the "data" member.
- Change iwl_calib_set()'s "len" argument to a size_t since it is always
  unsigned and is normally receiving the output of sizeof().
- Add an explicit length sanity check in iwl_calib_set().
- Adjust the memcpy() to avoid copying across the now visible composite
  flex array structure.

This avoids the future run-time warning:

  memcpy: detected field-spanning write (size 8) of single field "&res->hdr" (size 4)

Cc: Luca Coelho <luciano.coelho@intel.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Lee Jones <lee.jones@linaro.org>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Reported-by: Andy Lavr <andy.lavr@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20220901204558.2256458-1-keescook@chromium.org

diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/agn.h b/drivers/net/wireless/intel/iwlwifi/dvm/agn.h
index 411a6f6..fefaa41 100644 (file)
--- a/drivers/net/wireless/intel/iwlwifi/dvm/agn.h
+++ b/drivers/net/wireless/intel/iwlwifi/dvm/agn.h
@@ -112,7 +112,7 @@ int iwl_load_ucode_wait_alive(struct iwl_priv *priv,
                              enum iwl_ucode_type ucode_type);
 int iwl_send_calib_results(struct iwl_priv *priv);
 int iwl_calib_set(struct iwl_priv *priv,
-                 const struct iwl_calib_hdr *cmd, int len);
+                 const struct iwl_calib_cmd *cmd, size_t len);
 void iwl_calib_free_results(struct iwl_priv *priv);
 int iwl_dump_nic_event_log(struct iwl_priv *priv, bool full_log,
                            char **buf);

diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/calib.c b/drivers/net/wireless/intel/iwlwifi/dvm/calib.c
index a11884f..f488620 100644 (file)
--- a/drivers/net/wireless/intel/iwlwifi/dvm/calib.c
+++ b/drivers/net/wireless/intel/iwlwifi/dvm/calib.c
@@ -19,8 +19,7 @@
 struct iwl_calib_result {
        struct list_head list;
        size_t cmd_len;
-       struct iwl_calib_hdr hdr;
-       /* data follows */
+       struct iwl_calib_cmd cmd;
 };
 
 struct statistics_general_data {
@@ -43,12 +42,12 @@ int iwl_send_calib_results(struct iwl_priv *priv)
                int ret;
 
                hcmd.len[0] = res->cmd_len;
-               hcmd.data[0] = &res->hdr;
+               hcmd.data[0] = &res->cmd;
                hcmd.dataflags[0] = IWL_HCMD_DFL_NOCOPY;
                ret = iwl_dvm_send_cmd(priv, &hcmd);
                if (ret) {
                        IWL_ERR(priv, "Error %d on calib cmd %d\n",
-                               ret, res->hdr.op_code);
+                               ret, res->cmd.hdr.op_code);
                        return ret;
                }
        }
@@ -57,19 +56,22 @@ int iwl_send_calib_results(struct iwl_priv *priv)
 }
 
 int iwl_calib_set(struct iwl_priv *priv,
-                 const struct iwl_calib_hdr *cmd, int len)
+                 const struct iwl_calib_cmd *cmd, size_t len)
 {
        struct iwl_calib_result *res, *tmp;
 
-       res = kmalloc(sizeof(*res) + len - sizeof(struct iwl_calib_hdr),
-                     GFP_ATOMIC);
+       if (check_sub_overflow(len, sizeof(*cmd), &len))
+               return -ENOMEM;
+
+       res = kmalloc(struct_size(res, cmd.data, len), GFP_ATOMIC);
        if (!res)
                return -ENOMEM;
-       memcpy(&res->hdr, cmd, len);
-       res->cmd_len = len;
+       res->cmd = *cmd;
+       memcpy(res->cmd.data, cmd->data, len);
+       res->cmd_len = struct_size(cmd, data, len);
 
        list_for_each_entry(tmp, &priv->calib_results, list) {
-               if (tmp->hdr.op_code == res->hdr.op_code) {
+               if (tmp->cmd.hdr.op_code == res->cmd.hdr.op_code) {
                        list_replace(&tmp->list, &res->list);
                        kfree(tmp);
                        return 0;

diff --git a/drivers/net/wireless/intel/iwlwifi/dvm/ucode.c b/drivers/net/wireless/intel/iwlwifi/dvm/ucode.c
index 4b27a53..bb13ca5 100644 (file)
--- a/drivers/net/wireless/intel/iwlwifi/dvm/ucode.c
+++ b/drivers/net/wireless/intel/iwlwifi/dvm/ucode.c
@@ -356,18 +356,18 @@ static bool iwlagn_wait_calib(struct iwl_notif_wait_data *notif_wait,
                              struct iwl_rx_packet *pkt, void *data)
 {
        struct iwl_priv *priv = data;
-       struct iwl_calib_hdr *hdr;
+       struct iwl_calib_cmd *cmd;
 
        if (pkt->hdr.cmd != CALIBRATION_RES_NOTIFICATION) {
                WARN_ON(pkt->hdr.cmd != CALIBRATION_COMPLETE_NOTIFICATION);
                return true;
        }
 
-       hdr = (struct iwl_calib_hdr *)pkt->data;
+       cmd = (struct iwl_calib_cmd *)pkt->data;
 
-       if (iwl_calib_set(priv, hdr, iwl_rx_packet_payload_len(pkt)))
+       if (iwl_calib_set(priv, cmd, iwl_rx_packet_payload_len(pkt)))
                IWL_ERR(priv, "Failed to record calibration data %d\n",
-                       hdr->op_code);
+                       cmd->hdr.op_code);
 
        return false;
 }