From bc11c708d2cb8abd428d92a1e843a75f44be6356 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Mon, 3 Nov 2014 13:57:46 +0100 Subject: [PATCH] mac80211: fix use-after-free in defragmentation commit b8fff407a180286aa683d543d878d98d9fc57b13 upstream. 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. Reported-by: Yosef Khyal Signed-off-by: Johannes Berg Signed-off-by: Ben Hutchings --- net/mac80211/rx.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/net/mac80211/rx.c b/net/mac80211/rx.c index 71d85647c9df..2064612830ef 100644 --- a/net/mac80211/rx.c +++ b/net/mac80211/rx.c @@ -1470,11 +1470,14 @@ 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)) @@ -1567,10 +1570,7 @@ 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; } -- 2.39.5