Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <5599cc3b-8925-4cfd-f035-ae3b87e821a3@ugent.be>
Date:   Sun, 20 Feb 2022 18:54:40 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.5.1
Content-Language: en-US
To:     "David S. Miller" <davem@davemloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        David Ahern <dsahern@kernel.org>
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org
From:   Niels Dossche <niels.dossche@ugent.be>
Subject: [PATCH] ipv6: prevent a possible race condition with lifetimes
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?WlBxUnBGUmJDcU5ka05FY1NHU083R3JPNmtCN25zUzVjUThJTEJ3MmJmN25K?=
 =?utf-8?B?cHIwWW9COGc0V3FGRFZGTUZDNlNQZmxDSjVFNktnQjRmODRsdjRFKy94cUhO?=
 =?utf-8?B?Z2R4a1NNMmJFSVBMSmIwY1RjTk11R2c4eDFFK3krK2FXMm41SVpFTGUyTzc3?=
 =?utf-8?B?ak0rYXorbEsxNGsvQTlzdFpEankzUHByOTRtUmljZGJUanRrY2JoSUpkQW9W?=
 =?utf-8?B?YVY0QU83OHVIT3lYRzJ5ZU5ZakpoWmo4SnBmakx6Qis5QUFORDZQT1N6Mzg2?=
 =?utf-8?B?Y3BnVnpmLzlNNmJDVDZ3RlZpQzJDZXdrcGZHZVJBanQvMU1hZGNlUkR4aDdy?=
 =?utf-8?B?TkFnQzRUZjBjS1Z0T3QxOWl1ZEZTQXpKeGh0U09ua3IyaEJyQkQvZUFDQzZR?=
 =?utf-8?B?OHBlaXJBMkZ3a1N0NnNUaU1zVEFta1VuUnNpdk9mYkE5NHVNVFQ4bHNyQUto?=
 =?utf-8?B?Z3FhbXVucWF4SXZHYjkrbnNaaTFwbHlNbHRjMk9UQVp0VUdITVNZNkVVUjJS?=
 =?utf-8?B?Z2V1QnNFZGxFSnpIbWZkY2daQzVXblNIc2o3a3F4NThNV3JrejM3a09haWpZ?=
 =?utf-8?B?NDBuNHRubEYxRGRrQVdRS3k2OE04VUp6NWI3UXpGVmZ2Wm1qK2xVN0NrUERr?=
 =?utf-8?B?cGlkTGUzU2NNSjd4eEc1QjQ1Y0U2VHNYRGZaVXhFeVhYakYzM2dObzJkZkFz?=
 =?utf-8?B?WEtnZ29BYXhpdUFTQThVb1h4c1BTZFVVTnE1bjkzQ2o4ZnRNNDhBRnhlRHo0?=
 =?utf-8?B?OHJMSzR4cHhYQklOWms3T1F0dW8rckpWMWJNdmg4aFFsQVdwNWd2aTRSUzlK?=
 =?utf-8?B?K09qVUdubHFWK1JvZjd2RCtrTGtJRXExNVBUSlFwcmxORGFVZ3N4ZHEvbXRF?=
 =?utf-8?B?c2xodXNRK0VtTjdYR3NoRUJYSkJDejJZdTg1WmVxU0hvN1lyK1pwQ2JEbFZV?=
 =?utf-8?B?aXl1S0NpMWNUYmZWcnhCcjdsTTJFMllZdjNXaUN4M1lRZmhvdjlkVUFMbVc4?=
 =?utf-8?B?dExEOFZmVHVQRnFOZ0Zzd2lUeGdyK3E3UWtJbTIyZXllV2M2UGY1dzdkbVh2?=
 =?utf-8?B?RDQ4YmFkQ2NBS2tmdm5UK0x3ekJpeTYvbUhyTFZQUzRObkpYNjNJMFBOS3JM?=
 =?utf-8?B?Um1TMkxsQi80UXdISi92U215RS8zclVqTWlZbmY5YmtqZ1BVNXRreEc5V2pz?=
 =?utf-8?B?a1lKT0xQSFVnSUJxV2J4ZUladlI2NUxqRUZEU2lXaUx1WGUvUFd6Y1pwdWxR?=
 =?utf-8?B?SnNkeTFZTnRSVzNHdWtNRmZ1VjZYRG90M3dXSmRMNitkOC91YStTU0xOSkN6?=
 =?utf-8?B?N3M5NHFORUJSOElEQzJ2b3lmVGlueC9uNm8rTmREdlRsaDFkeVpRTXRTSjJk?=
 =?utf-8?B?WHZZZy9IOTdDYm56VGxoRi9BVy9MclVQM0MxTVBDUXo2R0RBQkQvMFdmeGFC?=
 =?utf-8?B?TmFjL1FUQlRxVGpLelIxWlhrODdSTi9PWk1GQVh6UU9vZ3BtWWNFT3U4WlU1?=
 =?utf-8?B?bWZRaGJHbXMwVXc4dE5hcU1zUWJ0VWRvZzRQV05MeU1yc3NzbnpGekhPczF3?=
 =?utf-8?B?dW9SbDVPOEJpbGZiMWxWQWR1RjEyYjB1M3NSN0N5dTZ2U2hrOVdxaFgwcEg0?=
 =?utf-8?B?a2w3WllUZXZ4MU5GeFd2MFhDSEhZajN2TndTaDcxUHBKOU9Oc2dNMS9SSVZU?=
 =?utf-8?B?Y2YwU09IZXdPV3pXVFkzRGlHVXpRcnVqUkpUckpsa2F5Ky92OGMxeFNXbWR2?=
 =?utf-8?B?QjUwNzViK25RVCtYUjBFSVRyc3IxckYySi85OVJkSzh2dEVBZ1ZKTWdselNp?=
 =?utf-8?B?bThlN3lQNVM5ZGo2cFdWL0J1Y20wamxueHlucHM3QnUzbERUNzBOQ0JlUlhy?=
 =?utf-8?B?Z3R3N1JjMlIxZ0wwcDRkcUljd2FWQUhUNFh0M3BKb3VvQ05wTzFpKzlQT1RJ?=
 =?utf-8?B?MC9sdnFxMmFZNTR3RnRqNmFVd1QwbmxzQnRSdzFmcFJWMkF2aGNQdzB0UkVv?=
 =?utf-8?B?eE1nYnBTUWltN0V6SWlncGFxQkZQczhHenpYcnBpVWFTYk9xMnJ4OG1wbmlE?=
 =?utf-8?B?eldrQUlzTDY5Y2FzNmUyMHNqTnF2TjV4UHZHMkRoN2puRW5TYXV3R1lrbGhF?=
 =?utf-8?B?SFZRL1FtQTB3ZnFta1Vma0RpZU5saHUwWXhBd2NtcTBnMlUvQnBvWHo2Ky9C?=
 =?utf-8?Q?EfR1u2c0Ago/h19Tevo7yYE=3D?=
X-OriginatorOrg: ugent.be
X-MS-Exchange-CrossTenant-Network-Message-Id: 6e1e11e7-36a2-4096-0343-08d9f49a1343
X-MS-Exchange-CrossTenant-AuthSource: AM0PR09MB2324.eurprd09.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Feb 2022 17:54:43.6654
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: d7811cde-ecef-496c-8f91-a1786241b99c
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: VaHK8WcnJ7HpIYTUm4FrJyXYoXImPmHVmWXgIZ9MNsWhUFm4kiZvJ+udmqUKAvgL8omJ+VP/Jam+HRTNvEToeA==
X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR09MB3760
X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,
        RCVD_IN_MSPIKE_H2,SPF_HELO_PASS,SPF_PASS,T_SCC_BODY_TEXT_LINE
        autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

valid_lft, prefered_lft and tstamp are always accessed under the lock
"lock" in other places. Reading these without taking the lock may result
in inconsistencies regarding the calculation of the valid and preferred
variables since decisions are taken on these fields for those variables.

Signed-off-by: Niels Dossche <niels.dossche@ugent.be>
---
 net/ipv6/addrconf.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 3f23da8c0b10..6c8ab3e6e6fe 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -4998,6 +4998,7 @@ static int inet6_fill_ifaddr(struct sk_buff *skb, struct inet6_ifaddr *ifa,
            nla_put_s32(skb, IFA_TARGET_NETNSID, args->netnsid))
                goto error;
 
+       spin_lock_bh(&ifa->lock);
        if (!((ifa->flags&IFA_F_PERMANENT) &&
              (ifa->prefered_lft == INFINITY_LIFE_TIME))) {
                preferred = ifa->prefered_lft;
@@ -5019,6 +5020,7 @@ static int inet6_fill_ifaddr(struct sk_buff *skb, struct inet6_ifaddr *ifa,
                preferred = INFINITY_LIFE_TIME;
                valid = INFINITY_LIFE_TIME;
        }
+       spin_unlock_bh(&ifa->lock);
 
        if (!ipv6_addr_any(&ifa->peer_addr)) {
                if (nla_put_in6_addr(skb, IFA_LOCAL, &ifa->addr) < 0 ||
-- 
2.35.1