staging: r8188eu: prevent array underflow in rtw_hal_update_ra_mask()

The problem is that "mac_id" is a u32 so this check for underflow does
not work when "mac_id" is zero.  In that situation, "mac_id - 1" is
UINT_MAX instead of -1 so the condition is true.  It leads to an
array underflow on the next line.

Fixes: 8cd574e6af54 ("staging: r8188eu: introduce new hal dir for RTL8188eu driver")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Link: https://lore.kernel.org/r/20210930122604.GB10068@kili
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/r8188eu/hal/hal_intf.c b/drivers/staging/r8188eu/hal/hal_intf.c
index a6d589e89aeb01f171829aa180f0a34f97052baf..f27eba72d646f116d8e6eaf364ed5b7fd8da5391 100644 (file)
--- a/drivers/staging/r8188eu/hal/hal_intf.c
+++ b/drivers/staging/r8188eu/hal/hal_intf.c
@@ -248,7 +248,7 @@ void rtw_hal_update_ra_mask(struct adapter *adapt, u32 mac_id, u8 rssi_level)
 #ifdef CONFIG_88EU_AP_MODE
                struct sta_info *psta = NULL;
                struct sta_priv *pstapriv = &adapt->stapriv;
-               if ((mac_id - 1) > 0)
+               if (mac_id >= 2)
                        psta = pstapriv->sta_aid[(mac_id - 1) - 1];
                if (psta)
                        add_RATid(adapt, psta, 0);/* todo: based on rssi_level*/