mac80211: move WEP tailroom size check

Remove checking tailroom when adding IV as it uses only
headroom, and move the check to the ICV generation that
actually needs the tailroom.

In other case I hit such warning and datapath don't work,
when testing:
- IBSS + WEP
- ath9k with hw crypt enabled
- IPv6 data (ping6)

WARNING: CPU: 3 PID: 13301 at net/mac80211/wep.c:102 ieee80211_wep_add_iv+0x129/0x190 [mac80211]()
[...]
Call Trace:
[<ffffffff817bf491>] dump_stack+0x45/0x57
[<ffffffff8107746a>] warn_slowpath_common+0x8a/0xc0
[<ffffffff8107755a>] warn_slowpath_null+0x1a/0x20
[<ffffffffc09ae109>] ieee80211_wep_add_iv+0x129/0x190 [mac80211]
[<ffffffffc09ae7ab>] ieee80211_crypto_wep_encrypt+0x6b/0xd0 [mac80211]
[<ffffffffc09d3fb1>] invoke_tx_handlers+0xc51/0xf30 [mac80211]
[...]

Cc: stable@vger.kernel.org
Signed-off-by: Janusz Dziedzic <janusz.dziedzic@tieto.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/wep.c b/net/mac80211/wep.c
index a4220e92f0cc20c0feb04c307f6ed72097f4fe3a..efa3f48f1ec5d51ea7191c8ae90dda77c0d330e1 100644 (file)
--- a/net/mac80211/wep.c
+++ b/net/mac80211/wep.c
@@ -98,8 +98,7 @@ static u8 *ieee80211_wep_add_iv(struct ieee80211_local *local,
 
        hdr->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
 
-       if (WARN_ON(skb_tailroom(skb) < IEEE80211_WEP_ICV_LEN ||
-                   skb_headroom(skb) < IEEE80211_WEP_IV_LEN))
+       if (WARN_ON(skb_headroom(skb) < IEEE80211_WEP_IV_LEN))
                return NULL;
 
        hdrlen = ieee80211_hdrlen(hdr->frame_control);
@@ -167,6 +166,9 @@ int ieee80211_wep_encrypt(struct ieee80211_local *local,
        size_t len;
        u8 rc4key[3 + WLAN_KEY_LEN_WEP104];
 
+       if (WARN_ON(skb_tailroom(skb) < IEEE80211_WEP_ICV_LEN))
+               return -1;
+
        iv = ieee80211_wep_add_iv(local, skb, keylen, keyidx);
        if (!iv)
                return -1;