ath9k: fix tx99 potential info leak

[ Upstream commit ee0a47186e2fa9aa1c56cadcea470ca0ba8c8692 ]

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>
Reviewed-by: Christoph Böhmwalder <christoph@boehmwalder.at>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/wireless/ath/ath9k/tx99.c b/drivers/net/wireless/ath/ath9k/tx99.c
index 2ea3589f709f5587685cb19e6e92a22ef83228b0..b7ab8455ffbd9561e3f31e664073d2251d17dd4b 100644 (file)
--- a/drivers/net/wireless/ath/ath9k/tx99.c
+++ b/drivers/net/wireless/ath/ath9k/tx99.c
@@ -180,6 +180,9 @@ 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;
 
@@ -187,6 +190,8 @@ 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;