[PATCH 3.8 52/91] mac80211: fix crash if bitrate calculation goes wrong

Kamal Mostafa kamal at canonical.com
Fri Nov 8 02:15:07 UTC 2013 -stable review patch.  If anyone has any objections, please let me know.


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

commit d86aa4f8ca58898ec6a94c0635da20b948171ed7 upstream.

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 at gmail.com>
Signed-off-by: Johannes Berg <johannes.berg at intel.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 net/mac80211/util.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/mac80211/util.c b/net/mac80211/util.c
index f11e8c5..e0ad72d 100644
--- a/net/mac80211/util.c
+++ b/net/mac80211/util.c
@@ -2105,6 +2105,10 @@ 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)

More information about the kernel-team mailing list