ath5k: warn and correct rate for unknown hw rate indexes

ath5k sets up a mapping table from the hardware rate index to
the rate index used by mac80211; however, we have seen some
received frames with incorrect rate indexes.  Such frames
normally get dropped with a warning in __ieee80211_rx(),
but it doesn't include enough information to track down the
error.

This patch adds a warning to hw_to_driver_rix for any lookups
that result in a rate index of -1, then returns a valid rate so
the frame can be processed.

Changes-licensed-under: 3-Clause-BSD

Signed-off-by: Bob Copeland <me@bobcopeland.com>
Cc: stable@kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>

2 files changed, 13 insertions, 4 deletions

diff --git a/drivers/net/wireless/ath5k/base.c b/drivers/net/wireless/ath5k/base.c
index f28b86c5d346..6580df2f7443 100644
--- a/drivers/net/wireless/ath5k/base.c
+++ b/drivers/net/wireless/ath5k/base.c
@@ -1088,9 +1088,18 @@ ath5k_mode_setup(struct ath5k_softc *sc)
 static inline int
 ath5k_hw_to_driver_rix(struct ath5k_softc *sc, int hw_rix)
 {
-        WARN(hw_rix < 0 || hw_rix >= AR5K_MAX_RATES,
-                        "hw_rix out of bounds: %x\n", hw_rix);
-        return sc->rate_idx[sc->curband->band][hw_rix];
+        int rix;
+
+        /* return base rate on errors */
+        if (WARN(hw_rix < 0 || hw_rix >= AR5K_MAX_RATES,
+                        "hw_rix out of bounds: %x\n", hw_rix))
+                return 0;
+
+        rix = sc->rate_idx[sc->curband->band][hw_rix];
+        if (WARN(rix < 0, "invalid hw_rix: %x\n", hw_rix))
+                rix = 0;
+
+        return rix;
 }
 
 /***************\
diff --git a/drivers/net/wireless/ath5k/base.h b/drivers/net/wireless/ath5k/base.h
index 20e0d14b41ec..822956114cd7 100644
--- a/drivers/net/wireless/ath5k/base.h
+++ b/drivers/net/wireless/ath5k/base.h
@@ -112,7 +112,7 @@ struct ath5k_softc {
         struct ieee80211_supported_band sbands[IEEE80211_NUM_BANDS];
         struct ieee80211_channel channels[ATH_CHAN_MAX];
         struct ieee80211_rate   rates[IEEE80211_NUM_BANDS][AR5K_MAX_RATES];
-        u8                      rate_idx[IEEE80211_NUM_BANDS][AR5K_MAX_RATES];
+        s8                      rate_idx[IEEE80211_NUM_BANDS][AR5K_MAX_RATES];
         enum nl80211_iftype     opmode;
         struct ath5k_hw         *ah;            /* Atheros HW */