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42 lines
1.6 KiB
Diff
42 lines
1.6 KiB
Diff
From 35f432a03e41d3bf08c51ede917f94e2288fbe8c Mon Sep 17 00:00:00 2001
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From: Johannes Berg <johannes.berg@intel.com>
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Date: Mon, 2 Jan 2017 11:19:29 +0100
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Subject: [PATCH] mac80211: initialize fast-xmit 'info' later
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In ieee80211_xmit_fast(), 'info' is initialized to point to the skb
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that's passed in, but that skb may later be replaced by a clone (if
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it was shared), leading to an invalid pointer.
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This can lead to use-after-free and also later crashes since the
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real SKB's info->hw_queue doesn't get initialized properly.
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Fix this by assigning info only later, when it's needed, after the
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skb replacement (may have) happened.
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Cc: stable@vger.kernel.org
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Reported-by: Ben Greear <greearb@candelatech.com>
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Signed-off-by: Johannes Berg <johannes.berg@intel.com>
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---
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net/mac80211/tx.c | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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--- a/net/mac80211/tx.c
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+++ b/net/mac80211/tx.c
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@@ -3297,7 +3297,7 @@ static bool ieee80211_xmit_fast(struct i
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int extra_head = fast_tx->hdr_len - (ETH_HLEN - 2);
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int hw_headroom = sdata->local->hw.extra_tx_headroom;
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struct ethhdr eth;
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- struct ieee80211_tx_info *info = IEEE80211_SKB_CB(skb);
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+ struct ieee80211_tx_info *info;
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struct ieee80211_hdr *hdr = (void *)fast_tx->hdr;
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struct ieee80211_tx_data tx;
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ieee80211_tx_result r;
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@@ -3361,6 +3361,7 @@ static bool ieee80211_xmit_fast(struct i
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memcpy(skb->data + fast_tx->da_offs, eth.h_dest, ETH_ALEN);
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memcpy(skb->data + fast_tx->sa_offs, eth.h_source, ETH_ALEN);
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+ info = IEEE80211_SKB_CB(skb);
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memset(info, 0, sizeof(*info));
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info->band = fast_tx->band;
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info->control.vif = &sdata->vif;
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