netdev - [PATCH] batman-adv: initialize "struct batadv_tvlv_tt_vlan

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Message-Id: <20210405053306.3437-1-penguin-kernel@I-love.SAKURA.ne.jp>
Date:   Mon,  5 Apr 2021 14:33:06 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Marek Lindner <mareklindner@...mailbox.ch>,
        Simon Wunderlich <sw@...onwunderlich.de>,
        Antonio Quartulli <a@...table.cc>,
        Sven Eckelmann <sven@...fation.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org,
        Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Subject: [PATCH] batman-adv: initialize "struct batadv_tvlv_tt_vlan_data"->reserved field

KMSAN found uninitialized value at batadv_tt_prepare_tvlv_local_data()
[1], for commit ced72933a5e8ab52 ("batman-adv: use CRC32C instead of CRC16
in TT code") inserted 'reserved' field into "struct batadv_tvlv_tt_data"
and commit 7ea7b4a142758dea ("batman-adv: make the TT CRC logic VLAN
specific") moved that field to "struct batadv_tvlv_tt_vlan_data" but left
that field uninitialized.

Although this patch passed "#syz test:" check, there might be similar bugs
remaining. It might be better to proactively use __GFP_ZERO than trying to
find uninitialized fields in this module.

[1] https://syzkaller.appspot.com/bug?id=07f3e6dba96f0eb3cabab986adcd8a58b9bdbe9d

Reported-by: syzbot <syzbot+50ee810676e6a089487b@...kaller.appspotmail.com>
Tested-by: syzbot <syzbot+50ee810676e6a089487b@...kaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Fixes: ced72933a5e8ab52 ("batman-adv: use CRC32C instead of CRC16 in TT code")
Fixes: 7ea7b4a142758dea ("batman-adv: make the TT CRC logic VLAN specific")
---
 net/batman-adv/translation-table.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/batman-adv/translation-table.c b/net/batman-adv/translation-table.c
index f8761281aab0..eb82576557e6 100644
--- a/net/batman-adv/translation-table.c
+++ b/net/batman-adv/translation-table.c
@@ -973,6 +973,7 @@ batadv_tt_prepare_tvlv_local_data(struct batadv_priv *bat_priv,
 
 		tt_vlan->vid = htons(vlan->vid);
 		tt_vlan->crc = htonl(vlan->tt.crc);
+		tt_vlan->reserved = 0;
 
 		tt_vlan++;
 	}
-- 
2.18.4