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SubjectRe: [PATCH] ipvs:set sock send/receive buffer correctly
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On 04/17/2019 02:18 AM, linmiaohe wrote:
> From: Jie Liu <liujie165@huawei.com>
>
> If we set sysctl_wmem_max or sysctl_rmem_max larger than INT_MAX,
> the send/receive buffer of sock will be an negative value. Same as
> when the val is larger than INT_MAX/2.
>
> Fixes: 1c003b1580e2 ("ipvs: wakeup master thread")
> Reported-by: Qiang Ning <ningqiang1@huawei.com>
> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>
> Signed-off-by: Jie Liu <liujie165@huawei.com>
> ---
> net/netfilter/ipvs/ip_vs_sync.c | 10 ++++------
> 1 file changed, 4 insertions(+), 6 deletions(-)
>
> diff --git a/net/netfilter/ipvs/ip_vs_sync.c b/net/netfilter/ipvs/ip_vs_sync.c
> index 2526be6b3d90..c0e4cbed6e74 100644
> --- a/net/netfilter/ipvs/ip_vs_sync.c
> +++ b/net/netfilter/ipvs/ip_vs_sync.c
> @@ -1278,14 +1278,12 @@ static void set_sock_size(struct sock *sk, int mode, int val)
> /* setsockopt(sock, SOL_SOCKET, SO_RCVBUF, &val, sizeof(val)); */
> lock_sock(sk);
> if (mode) {
> - val = clamp_t(int, val, (SOCK_MIN_SNDBUF + 1) / 2,
> - sysctl_wmem_max);
> - sk->sk_sndbuf = val * 2;
> + val = min_t(u32, val, sysctl_wmem_max);
> + sk->sk_sndbuf = max_t(int, val * 2, SOCK_MIN_SNDBUF);

What prevents val * 2 to overflow ?

Code in sock_setsockopt() looks quite different.

> sk->sk_userlocks |= SOCK_SNDBUF_LOCK;
> } else {
> - val = clamp_t(int, val, (SOCK_MIN_RCVBUF + 1) / 2,
> - sysctl_rmem_max);
> - sk->sk_rcvbuf = val * 2;
> + val = min_t(u32, val, sysctl_rmem_max);
> + sk->sk_rcvbuf = max_t(int, val * 2, SOCK_MIN_RCVBUF);
> sk->sk_userlocks |= SOCK_RCVBUF_LOCK;
> }
> release_sock(sk);
>

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