[PATCH] ath9k: fix tx99 potential info leak

[miaoqing@codeaurora.org]

From: Miaoqing Pan <miaoqing@codeaurora.org>

When the user sets count to zero the string buffer would remain
completely uninitialized which causes the kernel to parse its
own stack data, potentially leading to an info leak. In addition
to that, the string might be not terminated properly when the
user data does not contain a 0-terminator.

Signed-off-by: Miaoqing Pan <miaoqing@codeaurora.org>
---
 drivers/net/wireless/ath/ath9k/tx99.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/wireless/ath/ath9k/tx99.c b/drivers/net/wireless/ath/ath9k/tx99.c
index 49ed1af..fe3a826 100644
--- a/drivers/net/wireless/ath/ath9k/tx99.c
+++ b/drivers/net/wireless/ath/ath9k/tx99.c
@@ -179,6 +179,9 @@ static ssize_t write_file_tx99(struct file *file, const char __user *user_buf,
 	ssize_t len;
 	int r;
 
+	if (count < 1)
+		return -EINVAL;
+
 	if (sc->cur_chan->nvifs > 1)
 		return -EOPNOTSUPP;
 
@@ -186,6 +189,8 @@ static ssize_t write_file_tx99(struct file *file, const char __user *user_buf,
 	if (copy_from_user(buf, user_buf, len))
 		return -EFAULT;
 
+	buf[len] = '\0';
+
 	if (strtobool(buf, &start))
 		return -EINVAL;
 
-- 
1.9.1