[PATCH] mac80211: add check on hw->max_signal value on ieee80211_register_hw

[PATCH] mac80211: add check on hw->max_signal value on ieee80211_register_hw

[andrea merello]

When IEEE80211_HW_SIGNAL_UNSPEC is set, mac80211 will perform a
division by max_signal in ieee80211_bss_info_update. If max_signal
is not properly set by the driver (for example it is zero) this
leads to a divide error and crash.
Thanks to Larry Finger, who pointed me to this.
This patch adds in ieee80211_register_hw one more check to detect
this condition and eventually returns -EINVAL, as already done for
other checks already performed there.

Signed-off-by: andrea merello <andrea.merello@gmail.com>
---
 net/mac80211/main.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index d767cfb..913307a 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -758,6 +758,9 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 	     local->hw.offchannel_tx_hw_queue >= local->hw.queues))
 		return -EINVAL;
 
+	if (hw->flags & IEEE80211_HW_SIGNAL_UNSPEC && hw->max_signal <= 0)
+		return -EINVAL;
+
 #ifdef CONFIG_PM
 	if (hw->wiphy->wowlan && (!local->ops->suspend || !local->ops->resume))
 		return -EINVAL;
-- 
1.8.3.2

Re: [PATCH] mac80211: add check on hw->max_signal value on ieee80211_register_hw

[Johannes Berg]

On Sun, 2014-01-19 at 22:21 +0100, andrea merello wrote:
> When IEEE80211_HW_SIGNAL_UNSPEC is set, mac80211 will perform a
> division by max_signal in ieee80211_bss_info_update. If max_signal
> is not properly set by the driver (for example it is zero) this
> leads to a divide error and crash.
> Thanks to Larry Finger, who pointed me to this.
> This patch adds in ieee80211_register_hw one more check to detect
> this condition and eventually returns -EINVAL, as already done for
> other checks already performed there.

Applied.

johannes

Re: [PATCH] mac80211: add check on hw->max_signal value on ieee80211_register_hw

[Krishna Chaitanya]

On Mon, Jan 20, 2014 at 2:51 AM, andrea merello
<andrea.merello@gmail.com> wrote:
>
> +       if (hw->flags &
> IEEE80211_HW_SIGNAL_UNSPEC && hw->max_signal <= 0)
> +               return -EINVAL;
> +

Should we add a check for > 100 as well, similar to cfg?