From b8fff407a180286aa683d543d878d98d9fc57b13 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 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 Signed-off-by: Johannes Berg --- 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 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; } -- 2.20.1