ath6kl: wmi: prevent a shift wrapping bug in ath6kl_wmi_delete_pstream_cmd()

The "tsid" is a user controlled u8 which comes from debugfs.  Values
more than 15 are invalid because "active_tsids" is a 16 bit variable.
If the value of "tsid" is more than 31 then that leads to a shift
wrapping bug.

Fixes: 8fffd9e5ec9e ("ath6kl: Implement support for QOS-enable and QOS-disable from userspace")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200918142732.GA909725@mwanda

diff --git a/drivers/net/wireless/ath/ath6kl/wmi.c b/drivers/net/wireless/ath/ath6kl/wmi.c
index a4339cc..dbc4770 100644 (file)
--- a/drivers/net/wireless/ath/ath6kl/wmi.c
+++ b/drivers/net/wireless/ath/ath6kl/wmi.c
@@ -2639,6 +2639,11 @@ int ath6kl_wmi_delete_pstream_cmd(struct wmi *wmi, u8 if_idx, u8 traffic_class,
                return -EINVAL;
        }
 
+       if (tsid >= 16) {
+               ath6kl_err("invalid tsid: %d\n", tsid);
+               return -EINVAL;
+       }
+
        skb = ath6kl_wmi_get_new_buf(sizeof(*cmd));
        if (!skb)
                return -ENOMEM;