[PATCH iwl-net v1] libie: prevent memleak in fwlog code

[Michal Swiatkowski <michal.swiatkowski@linux.intel.com>]

All cmd_buf buffers are allocated and need to be freed after usage.
Add an error unwinding path that properly frees these buffers.

The memory leak  happens whenever fwlog configuration is changed. For
example:

$echo 256K > /sys/kernel/debug/ixgbe/0000\:32\:00.0/fwlog/log_size

Fixes: 96a9a9341cda ("ice: configure FW logging")
Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@intel.com>
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
---
 drivers/net/ethernet/intel/libie/fwlog.c | 49 +++++++++++++++++-------
 1 file changed, 36 insertions(+), 13 deletions(-)

diff --git a/drivers/net/ethernet/intel/libie/fwlog.c b/drivers/net/ethernet/intel/libie/fwlog.c
index f39cc11cb7c5..30a6bd095f18 100644
--- a/drivers/net/ethernet/intel/libie/fwlog.c
+++ b/drivers/net/ethernet/intel/libie/fwlog.c
@@ -433,17 +433,21 @@ libie_debugfs_module_write(struct file *filp, const char __user *buf,
 	module = libie_find_module_by_dentry(fwlog->debugfs_modules, dentry);
 	if (module < 0) {
 		dev_info(dev, "unknown module\n");
-		return -EINVAL;
+		count = -EINVAL;
+		goto free_cmd_buf;
 	}
 
 	cnt = sscanf(cmd_buf, "%s", user_val);
-	if (cnt != 1)
-		return -EINVAL;
+	if (cnt != 1) {
+		count = -EINVAL;
+		goto free_cmd_buf;
+	}
 
 	log_level = sysfs_match_string(libie_fwlog_level_string, user_val);
 	if (log_level < 0) {
 		dev_info(dev, "unknown log level '%s'\n", user_val);
-		return -EINVAL;
+		count = -EINVAL;
+		goto free_cmd_buf;
 	}
 
 	if (module != LIBIE_AQC_FW_LOG_ID_MAX) {
@@ -458,6 +462,9 @@ libie_debugfs_module_write(struct file *filp, const char __user *buf,
 			fwlog->cfg.module_entries[i].log_level = log_level;
 	}
 
+free_cmd_buf:
+	kfree(cmd_buf);
+
 	return count;
 }
 
@@ -515,23 +522,31 @@ libie_debugfs_nr_messages_write(struct file *filp, const char __user *buf,
 		return PTR_ERR(cmd_buf);
 
 	ret = sscanf(cmd_buf, "%s", user_val);
-	if (ret != 1)
-		return -EINVAL;
+	if (ret != 1) {
+		count = -EINVAL;
+		goto free_cmd_buf;
+	}
 
 	ret = kstrtos16(user_val, 0, &nr_messages);
-	if (ret)
-		return ret;
+	if (ret) {
+		count = ret;
+		goto free_cmd_buf;
+	}
 
 	if (nr_messages < LIBIE_AQC_FW_LOG_MIN_RESOLUTION ||
 	    nr_messages > LIBIE_AQC_FW_LOG_MAX_RESOLUTION) {
 		dev_err(dev, "Invalid FW log number of messages %d, value must be between %d - %d\n",
 			nr_messages, LIBIE_AQC_FW_LOG_MIN_RESOLUTION,
 			LIBIE_AQC_FW_LOG_MAX_RESOLUTION);
-		return -EINVAL;
+		count = -EINVAL;
+		goto free_cmd_buf;
 	}
 
 	fwlog->cfg.log_resolution = nr_messages;
 
+free_cmd_buf:
+	kfree(cmd_buf);
+
 	return count;
 }
 
@@ -588,8 +603,10 @@ libie_debugfs_enable_write(struct file *filp, const char __user *buf,
 		return PTR_ERR(cmd_buf);
 
 	ret = sscanf(cmd_buf, "%s", user_val);
-	if (ret != 1)
-		return -EINVAL;
+	if (ret != 1) {
+		ret = -EINVAL;
+		goto free_cmd_buf;
+	}
 
 	ret = kstrtobool(user_val, &enable);
 	if (ret)
@@ -624,6 +641,8 @@ libie_debugfs_enable_write(struct file *filp, const char __user *buf,
 	 */
 	if (WARN_ON(ret != (ssize_t)count && ret >= 0))
 		ret = -EIO;
+free_cmd_buf:
+	kfree(cmd_buf);
 
 	return ret;
 }
@@ -682,8 +701,10 @@ libie_debugfs_log_size_write(struct file *filp, const char __user *buf,
 		return PTR_ERR(cmd_buf);
 
 	ret = sscanf(cmd_buf, "%s", user_val);
-	if (ret != 1)
-		return -EINVAL;
+	if (ret != 1) {
+		ret = -EINVAL;
+		goto free_cmd_buf;
+	}
 
 	index = sysfs_match_string(libie_fwlog_log_size, user_val);
 	if (index < 0) {
@@ -712,6 +733,8 @@ libie_debugfs_log_size_write(struct file *filp, const char __user *buf,
 	 */
 	if (WARN_ON(ret != (ssize_t)count && ret >= 0))
 		ret = -EIO;
+free_cmd_buf:
+	kfree(cmd_buf);
 
 	return ret;
 }
-- 
2.49.0