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From:   YueHaibing <yuehaibing@huawei.com>
To:     <davem@davemloft.net>, <steffen.klassert@secunet.com>,
        <herbert@gondor.apana.org.au>, <kuznet@ms2.inr.ac.ru>,
        <yoshfuji@linux-ipv6.org>
CC:     <linux-kernel@vger.kernel.org>, <netdev@vger.kernel.org>,
        YueHaibing <yuehaibing@huawei.com>
Subject: [PATCH net-next] xfrm6_tunnel: Fix spi check in __xfrm6_tunnel_alloc_spi
Date:   Wed, 19 Dec 2018 14:45:09 +0800
Message-ID: <20181219064509.9804-1-yuehaibing@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

gcc warn this:

net/ipv6/xfrm6_tunnel.c:143 __xfrm6_tunnel_alloc_spi() warn:
 always true condition '(spi <= 4294967295) => (0-u32max <= u32max)'

'spi' is u32, which always not greater than XFRM6_TUNNEL_SPI_MAX
because of wrap around. So the second forloop will never reach.

Signed-off-by: YueHaibing <yuehaibing@huawei.com>
---
 net/ipv6/xfrm6_tunnel.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ipv6/xfrm6_tunnel.c b/net/ipv6/xfrm6_tunnel.c
index 4a46df8..f5b4feb 100644
--- a/net/ipv6/xfrm6_tunnel.c
+++ b/net/ipv6/xfrm6_tunnel.c
@@ -144,6 +144,9 @@ static u32 __xfrm6_tunnel_alloc_spi(struct net *net, xfrm_address_t *saddr)
 		index = __xfrm6_tunnel_spi_check(net, spi);
 		if (index >= 0)
 			goto alloc_spi;
+
+		if (spi == XFRM6_TUNNEL_SPI_MAX)
+			break;
 	}
 	for (spi = XFRM6_TUNNEL_SPI_MIN; spi < xfrm6_tn->spi; spi++) {
 		index = __xfrm6_tunnel_spi_check(net, spi);
-- 
2.7.0