diff mbox

[3.18] mac80211: fix use-after-free in defragmentation

Message ID 1415021349-30369-1-git-send-email-johannes@sipsolutions.net (mailing list archive)
State Not Applicable, archived
Headers show

Commit Message

Johannes Berg Nov. 3, 2014, 1:29 p.m. UTC 
From: Johannes Berg <johannes.berg@intel.com>

Upon receiving the last fragment, all but the first fragment
are freed, but the multicast check for statistics at the end
of the function refers to the current skb (the last fragment)
causing a use-after-free bug.

Since multicast frames cannot be fragmented and we check for
this early in the function, just modify that check to also
do the accounting to fix the issue.

Cc: stable@vger.kernel.org
Reported-by: Yosef Khyal <yosefx.khyal@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---
 net/mac80211/rx.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)
diff mbox

Patch

diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c
index b04ca4049c95..a37f9af634cb 100644
--- a/net/mac80211/rx.c
+++ b/net/mac80211/rx.c
@@ -1678,11 +1678,14 @@  ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
 	sc = le16_to_cpu(hdr->seq_ctrl);
 	frag = sc & IEEE80211_SCTL_FRAG;
 
-	if (likely((!ieee80211_has_morefrags(fc) && frag == 0) ||
-		   is_multicast_ether_addr(hdr->addr1))) {
-		/* not fragmented */
+	if (likely(!ieee80211_has_morefrags(fc) && frag == 0))
+		goto out;
+
+	if (is_multicast_ether_addr(hdr->addr1)) {
+		rx->local->dot11MulticastReceivedFrameCount++;
 		goto out;
 	}
+
 	I802_DEBUG_INC(rx->local->rx_handlers_fragments);
 
 	if (skb_linearize(rx->skb))
@@ -1775,10 +1778,7 @@  ieee80211_rx_h_defragment(struct ieee80211_rx_data *rx)
  out:
 	if (rx->sta)
 		rx->sta->rx_packets++;
-	if (is_multicast_ether_addr(hdr->addr1))
-		rx->local->dot11MulticastReceivedFrameCount++;
-	else
-		ieee80211_led_rx(rx->local);
+	ieee80211_led_rx(rx->local);
 	return RX_CONTINUE;
 }