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-rw-r--r--net/mac80211/tkip.c18
1 files changed, 15 insertions, 3 deletions
diff --git a/net/mac80211/tkip.c b/net/mac80211/tkip.c
index 727dc9f3f3b3..e7f57bb18f6e 100644
--- a/net/mac80211/tkip.c
+++ b/net/mac80211/tkip.c
@@ -263,9 +263,21 @@ int ieee80211_tkip_decrypt_data(struct arc4_ctx *ctx,
if ((keyid >> 6) != key->conf.keyidx)
return TKIP_DECRYPT_INVALID_KEYIDX;
- if (rx_ctx->ctx.state != TKIP_STATE_NOT_INIT &&
- (iv32 < rx_ctx->iv32 ||
- (iv32 == rx_ctx->iv32 && iv16 <= rx_ctx->iv16)))
+ /* Reject replays if the received TSC is smaller than or equal to the
+ * last received value in a valid message, but with an exception for
+ * the case where a new key has been set and no valid frame using that
+ * key has yet received and the local RSC was initialized to 0. This
+ * exception allows the very first frame sent by the transmitter to be
+ * accepted even if that transmitter were to use TSC 0 (IEEE 802.11
+ * described TSC to be initialized to 1 whenever a new key is taken into
+ * use).
+ */
+ if (iv32 < rx_ctx->iv32 ||
+ (iv32 == rx_ctx->iv32 &&
+ (iv16 < rx_ctx->iv16 ||
+ (iv16 == rx_ctx->iv16 &&
+ (rx_ctx->iv32 || rx_ctx->iv16 ||
+ rx_ctx->ctx.state != TKIP_STATE_NOT_INIT)))))
return TKIP_DECRYPT_REPLAY;
if (only_iv) {