From c4e8f65dc299b14f79a545748817be5ed48f0e0b Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Petr=20=C5=A0tetiar?= Date: Thu, 11 Apr 2019 20:13:30 +0200 Subject: [PATCH] mwl8k: Fix rate_idx underflow MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit 6b583201fa219b7b1b6aebd8966c8fd9357ef9f4 upstream. It was reported on OpenWrt bug tracking system[1], that several users are affected by the endless reboot of their routers if they configure 5GHz interface with channel 44 or 48. The reboot loop is caused by the following excessive number of WARN_ON messages: WARNING: CPU: 0 PID: 0 at backports-4.19.23-1/net/mac80211/rx.c:4516 ieee80211_rx_napi+0x1fc/0xa54 [mac80211] as the messages are being correctly emitted by the following guard: case RX_ENC_LEGACY: if (WARN_ON(status->rate_idx >= sband->n_bitrates)) as the rate_idx is in this case erroneously set to 251 (0xfb). This fix simply converts previously used magic number to proper constant and guards against substraction which is leading to the currently observed underflow. 1. https://bugs.openwrt.org/index.php?do=details&task_id=2218 Fixes: 854783444bab ("mwl8k: properly set receive status rate index on 5 GHz receive") Tested-by: Eubert Bao Reported-by: Eubert Bao Signed-off-by: Petr Štetiar Signed-off-by: Kalle Valo [bwh: Backported to 3.16: adjust filename, context] Signed-off-by: Ben Hutchings --- drivers/net/wireless/mwl8k.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/net/wireless/mwl8k.c b/drivers/net/wireless/mwl8k.c index 3c0a0a86ba12..fc4d897b1da7 100644 --- a/drivers/net/wireless/mwl8k.c +++ b/drivers/net/wireless/mwl8k.c @@ -436,6 +436,9 @@ static const struct ieee80211_rate mwl8k_rates_50[] = { #define MWL8K_CMD_UPDATE_STADB 0x1123 #define MWL8K_CMD_BASTREAM 0x1125 +#define MWL8K_LEGACY_5G_RATE_OFFSET \ + (ARRAY_SIZE(mwl8k_rates_24) - ARRAY_SIZE(mwl8k_rates_50)) + static const char *mwl8k_cmd_name(__le16 cmd, char *buf, int bufsize) { u16 command = le16_to_cpu(cmd); @@ -1011,8 +1014,9 @@ mwl8k_rxd_ap_process(void *_rxd, struct ieee80211_rx_status *status, if (rxd->channel > 14) { status->band = IEEE80211_BAND_5GHZ; - if (!(status->flag & RX_FLAG_HT)) - status->rate_idx -= 5; + if (!(status->flag & RX_FLAG_HT) && + status->rate_idx >= MWL8K_LEGACY_5G_RATE_OFFSET) + status->rate_idx -= MWL8K_LEGACY_5G_RATE_OFFSET; } else { status->band = IEEE80211_BAND_2GHZ; } @@ -1119,8 +1123,9 @@ mwl8k_rxd_sta_process(void *_rxd, struct ieee80211_rx_status *status, if (rxd->channel > 14) { status->band = IEEE80211_BAND_5GHZ; - if (!(status->flag & RX_FLAG_HT)) - status->rate_idx -= 5; + if (!(status->flag & RX_FLAG_HT) && + status->rate_idx >= MWL8K_LEGACY_5G_RATE_OFFSET) + status->rate_idx -= MWL8K_LEGACY_5G_RATE_OFFSET; } else { status->band = IEEE80211_BAND_2GHZ; }