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Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7)

From Johannes Berg <johannes@sipsolutions.net>
Newsgroups linux.kernel
Subject Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7)
Date 2016-10-12 16:30 +0200
Message-ID <srsHD-5Fa-1@gated-at.bofh.it> (permalink)
References (1 earlier) <sqKQi-2WG-17@gated-at.bofh.it> <srnHY-2dx-15@gated-at.bofh.it> <srsxY-5Bl-15@gated-at.bofh.it> <srsHD-5Fa-3@gated-at.bofh.it> <srsxY-5Bl-15@gated-at.bofh.it>
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> > Can you elaborate on how exactly it kills your system?
> 
> the last time I saw it it was a NULL deref at
> ieee80211_aes_ccm_decrypt.

Hm. I was expecting something within the crypto code would cause the
crash, this seems strange.

Anyway, I'm surely out of my depth wrt. the actual cause. Something
like the patch below probably works around it, but it's horribly
inefficient due to the locking and doesn't cover CMAC/GMAC either.

johannes

diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
index 103187ca9474..e820f437f02e 100644
--- a/net/mac80211/ieee80211_i.h
+++ b/net/mac80211/ieee80211_i.h
@@ -27,6 +27,7 @@
 #include <linux/leds.h>
 #include <linux/idr.h>
 #include <linux/rhashtable.h>
+#include <crypto/aes.h>
 #include <net/ieee80211_radiotap.h>
 #include <net/cfg80211.h>
 #include <net/mac80211.h>
@@ -1224,6 +1225,10 @@ struct ieee80211_local {
 
 	spinlock_t rx_path_lock;
 
+	/* temporary buffers for software crypto */
+	u8 aad[2 * AES_BLOCK_SIZE];
+	u8 b_0[AES_BLOCK_SIZE];
+
 	/* Station data */
 	/*
 	 * The mutex only protects the list, hash table and
diff --git a/net/mac80211/wpa.c b/net/mac80211/wpa.c
index b48c1e13e281..a3f17a710b85 100644
--- a/net/mac80211/wpa.c
+++ b/net/mac80211/wpa.c
@@ -405,8 +405,8 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb,
 	u8 *pos;
 	u8 pn[6];
 	u64 pn64;
-	u8 aad[2 * AES_BLOCK_SIZE];
-	u8 b_0[AES_BLOCK_SIZE];
+	u8 *aad = tx->local->aad;
+	u8 *b_0 = tx->local->b_0;
 
 	if (info->control.hw_key &&
 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
@@ -460,9 +460,11 @@ static int ccmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb,
 		return 0;
 
 	pos += IEEE80211_CCMP_HDR_LEN;
+	spin_lock_bh(&tx->local->rx_path_lock);
 	ccmp_special_blocks(skb, pn, b_0, aad);
 	ieee80211_aes_ccm_encrypt(key->u.ccmp.tfm, b_0, aad, pos, len,
 				  skb_put(skb, mic_len), mic_len);
+	spin_unlock_bh(&tx->local->rx_path_lock);
 
 	return 0;
 }
@@ -534,8 +536,9 @@ ieee80211_crypto_ccmp_decrypt(struct ieee80211_rx_data *rx,
 		}
 
 		if (!(status->flag & RX_FLAG_DECRYPTED)) {
-			u8 aad[2 * AES_BLOCK_SIZE];
-			u8 b_0[AES_BLOCK_SIZE];
+			u8 *aad = rx->local->aad;
+			u8 *b_0 = rx->local->b_0;
+
 			/* hardware didn't decrypt/verify MIC */
 			ccmp_special_blocks(skb, pn, b_0, aad);
 
@@ -639,8 +642,8 @@ static int gcmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 	u8 *pos;
 	u8 pn[6];
 	u64 pn64;
-	u8 aad[2 * AES_BLOCK_SIZE];
-	u8 j_0[AES_BLOCK_SIZE];
+	u8 *aad = tx->local->aad;
+	u8 *j_0 = tx->local->b_0;
 
 	if (info->control.hw_key &&
 	    !(info->control.hw_key->flags & IEEE80211_KEY_FLAG_GENERATE_IV) &&
@@ -695,9 +698,11 @@ static int gcmp_encrypt_skb(struct ieee80211_tx_data *tx, struct sk_buff *skb)
 		return 0;
 
 	pos += IEEE80211_GCMP_HDR_LEN;
+	spin_lock_bh(&tx->local->rx_path_lock);
 	gcmp_special_blocks(skb, pn, j_0, aad);
 	ieee80211_aes_gcm_encrypt(key->u.gcmp.tfm, j_0, aad, pos, len,
 				  skb_put(skb, IEEE80211_GCMP_MIC_LEN));
+	spin_unlock_bh(&tx->local->rx_path_lock);
 
 	return 0;
 }
@@ -764,8 +769,9 @@ ieee80211_crypto_gcmp_decrypt(struct ieee80211_rx_data *rx)
 		}
 
 		if (!(status->flag & RX_FLAG_DECRYPTED)) {
-			u8 aad[2 * AES_BLOCK_SIZE];
-			u8 j_0[AES_BLOCK_SIZE];
+			u8 *aad = rx->local->aad;
+			u8 *j_0 = rx->local->b_0;
+
 			/* hardware didn't decrypt/verify MIC */
 			gcmp_special_blocks(skb, pn, j_0, aad);

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Thread

[mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-10-10 17:10 +0200
  Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-10-10 17:40 +0200
    Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-12 11:10 +0200
      Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-10-12 16:20 +0200
        Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-12 16:30 +0200
          Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Andy Lutomirski <luto@amacapital.net> - 2016-10-13 08:10 +0200
            Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-13 08:10 +0200
              Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-10-13 15:50 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-10-13 16:10 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-13 16:20 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-10-13 17:10 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-10-13 17:30 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Andy Lutomirski <luto@amacapital.net> - 2016-10-14 00:00 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-14 09:30 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-14 10:30 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-14 10:40 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-14 10:50 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-14 11:00 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-14 11:10 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-14 11:20 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-14 11:30 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-14 11:40 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-14 12:10 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-14 13:20 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-14 11:30 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-10-14 10:50 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-14 10:50 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-14 11:00 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Johannes Berg <johannes@sipsolutions.net> - 2016-10-14 10:50 +0200
                Re: [mac80211] BUG_ON with current -git (4.8.0-11417-g24532f7) Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-10-14 10:50 +0200

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