2018-12-19 07:13:32

by Yue Haibing

Subject: [PATCH net-next] xfrm6_tunnel: Fix spi check in __xfrm6_tunnel_alloc_spi

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 <[email protected]>
---
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

2018-12-20 08:29:35

by Steffen Klassert

Subject: Re: [PATCH net-next] xfrm6_tunnel: Fix spi check in __xfrm6_tunnel_alloc_spi

On Wed, Dec 19, 2018 at 02:45:09PM +0800, YueHaibing wrote:
> 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 <[email protected]>

Also applied, thanks a lot!