iwlwifi: mvm: do string formatting in debug triggers

The current code has a lot of duplicates of printing into a buffer
(while having to make sure it's NUL-filled and -terminated) and
then passing that to the debug trigger collection.

Since that's error-prone, instead make the debug trigger collection
function take a format string and format arguments (with compiler
validity checking) and handle the buffer internally.

This makes one behavioural change -- instead of sending the whole
buffer to userspace (clearing is needed to not leak stack data) it
just passes the actual string (including NUL-terminator.)

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

1 files changed, 20 insertions, 3 deletions

diff --git a/drivers/net/wireless/iwlwifi/mvm/fw.c b/drivers/net/wireless/iwlwifi/mvm/fw.c
index 6cf7d9837ca5..bc5eac4960e1 100644
--- a/drivers/net/wireless/iwlwifi/mvm/fw.c
+++ b/drivers/net/wireless/iwlwifi/mvm/fw.c
@@ -526,16 +526,33 @@ int iwl_mvm_fw_dbg_collect(struct iwl_mvm *mvm, enum iwl_fw_dbg_trigger trig,
 
 int iwl_mvm_fw_dbg_collect_trig(struct iwl_mvm *mvm,
 				struct iwl_fw_dbg_trigger_tlv *trigger,
-				const char *str, size_t len)
+				const char *fmt, ...)
 {
 	unsigned int delay = msecs_to_jiffies(le32_to_cpu(trigger->stop_delay));
 	u16 occurrences = le16_to_cpu(trigger->occurrences);
-	int ret;
+	int ret, len = 0;
+	char buf[64];
 
 	if (!occurrences)
 		return 0;
 
-	ret = iwl_mvm_fw_dbg_collect(mvm, le32_to_cpu(trigger->id), str,
+	if (fmt) {
+		va_list ap;
+
+		buf[sizeof(buf) - 1] = '\0';
+
+		va_start(ap, fmt);
+		vsnprintf(buf, sizeof(buf), fmt, ap);
+		va_end(ap);
+
+		/* check for truncation */
+		if (WARN_ON_ONCE(buf[sizeof(buf) - 1]))
+			buf[sizeof(buf) - 1] = '\0';
+
+		len = strlen(buf) + 1;
+	}
+
+	ret = iwl_mvm_fw_dbg_collect(mvm, le32_to_cpu(trigger->id), buf,
 				     len, delay);
 	if (ret)
 		return ret;