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    Subject[PATCH 4.14 057/209] VSOCK: bind to random port for VMADDR_PORT_ANY
    Date
    From: Lepton Wu <ytht.net@gmail.com>

    [ Upstream commit 8236b08cf50f85bbfaf48910a0b3ee68318b7c4b ]

    The old code always starts from fixed port for VMADDR_PORT_ANY. Sometimes
    when VMM crashed, there is still orphaned vsock which is waiting for
    close timer, then it could cause connection time out for new started VM
    if they are trying to connect to same port with same guest cid since the
    new packets could hit that orphaned vsock. We could also fix this by doing
    more in vhost_vsock_reset_orphans, but any way, it should be better to start
    from a random local port instead of a fixed one.

    Signed-off-by: Lepton Wu <ytht.net@gmail.com>
    Reviewed-by: Jorgen Hansen <jhansen@vmware.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/vmw_vsock/af_vsock.c | 7 ++++++-
    1 file changed, 6 insertions(+), 1 deletion(-)

    diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
    index 1939b77e98b72..73eac97e19fb1 100644
    --- a/net/vmw_vsock/af_vsock.c
    +++ b/net/vmw_vsock/af_vsock.c
    @@ -107,6 +107,7 @@
    #include <linux/mutex.h>
    #include <linux/net.h>
    #include <linux/poll.h>
    +#include <linux/random.h>
    #include <linux/skbuff.h>
    #include <linux/smp.h>
    #include <linux/socket.h>
    @@ -487,9 +488,13 @@ out:
    static int __vsock_bind_stream(struct vsock_sock *vsk,
    struct sockaddr_vm *addr)
    {
    - static u32 port = LAST_RESERVED_PORT + 1;
    + static u32 port = 0;
    struct sockaddr_vm new_addr;

    + if (!port)
    + port = LAST_RESERVED_PORT + 1 +
    + prandom_u32_max(U32_MAX - LAST_RESERVED_PORT);
    +
    vsock_addr_init(&new_addr, addr->svm_cid, addr->svm_port);

    if (addr->svm_port == VMADDR_PORT_ANY) {
    --
    2.20.1


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