[PATCH 091/118] iwlwifi: fix freeing uninitialized pointer

[Luis Henriques]

3.5.7.12 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Stanislaw Gruszka <sgruszka at redhat.com>

commit 3309ccf7fcebceef540ebe90c65d2f94d745a45b upstream.

If on iwl_dump_nic_event_log() error occurs before that function
initialize buf, we process uninitiated pointer in
iwl_dbgfs_log_event_read() and can hit "BUG at mm/slub.c:3409"

Resolves:
https://bugzilla.redhat.com/show_bug.cgi?id=951241

Reported-by: ian.odette at eprize.com
Signed-off-by: Stanislaw Gruszka <sgruszka at redhat.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach at intel.com>
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
[ luis: backport to 3.5:
  - file rename: dvm/debugfs.c -> iwl-debugfs.c ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/wireless/iwlwifi/iwl-debugfs.c | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/iwl-debugfs.c b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
index 5000690..ba376ec 100644
--- a/drivers/net/wireless/iwlwifi/iwl-debugfs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
@@ -2248,15 +2248,15 @@ static ssize_t iwl_dbgfs_log_event_read(struct file *file,
 					 size_t count, loff_t *ppos)
 {
 	struct iwl_priv *priv = file->private_data;
-	char *buf;
-	int pos = 0;
-	ssize_t ret = -ENOMEM;
+	char *buf = NULL;
+	ssize_t ret;
 
-	ret = pos = iwl_dump_nic_event_log(priv, true, &buf, true);
-	if (buf) {
-		ret = simple_read_from_buffer(user_buf, count, ppos, buf, pos);
-		kfree(buf);
-	}
+	ret = iwl_dump_nic_event_log(priv, true, &buf, true);
+	if (ret < 0)
+		goto err;
+	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
+err:
+	kfree(buf);
 	return ret;
 }
 
-- 
1.8.1.2