[PATCH] mac80211: fix crash if bitrate calculation goes wrong

[PATCH] mac80211: fix crash if bitrate calculation goes wrong

[Johannes Berg]

From: Johannes Berg <johannes.berg@intel.com>

If a frame's timestamp is calculated, and the bitrate
calculation goes wrong and returns zero, the system
will attempt to divide by zero and crash. Catch this
case and print the rate information that the driver
reported when this happens.

Reported-by: Thomas Lindroth <thomas.lindroth@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/mac80211/util.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index 9c3200b..69e4ef5 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2238,6 +2238,10 @@ u64 ieee80211_calculate_rx_timestamp(struct ieee80211_local *local,
 	}
 
 	rate = cfg80211_calculate_bitrate(&ri);
+	if (WARN_ONCE(!rate,
+		      "Invalid bitrate: flags=0x%x, idx=%d, vht_nss=%d\n",
+		      status->flag, status->rate_idx, status->vht_nss))
+		return 0;
 
 	/* rewind from end of MPDU */
 	if (status->flag & RX_FLAG_MACTIME_END)
-- 
1.8.4.rc3

Re: [PATCH] mac80211: fix crash if bitrate calculation goes wrong

[Johannes Berg]

On Fri, 2013-10-11 at 15:48 +0200, Johannes Berg wrote:
> From: Johannes Berg <johannes.berg@intel.com>
> 
> If a frame's timestamp is calculated, and the bitrate
> calculation goes wrong and returns zero, the system
> will attempt to divide by zero and crash. Catch this
> case and print the rate information that the driver
> reported when this happens.

Applied.

johannes