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    Subject[PATCH AUTOSEL for 4.14 081/110] RDMA/netlink: Fix locking around __ib_get_device_by_index
    Date
    From: Leon Romanovsky <leonro@mellanox.com>

    [ Upstream commit f8978bd95cf92f869f3d9b34c1b699f49253b8c6 ]

    Holding locks is mandatory when calling __ib_device_get_by_index,
    otherwise there are races during the list iteration with device removal.

    Since the locks are static to device.c, __ib_device_get_by_index can
    never be called correctly by any user out side the file.

    Make the function static and provide a safe function that gets the
    correct locks and returns a kref'd pointer. Fix all callers.

    Fixes: e5c9469efcb1 ("RDMA/netlink: Add nldev device doit implementation")
    Fixes: c3f66f7b0052 ("RDMA/netlink: Implement nldev port doit callback")
    Fixes: 7d02f605f0dc ("RDMA/netlink: Add nldev port dumpit implementation")
    Reviewed-by: Mark Bloch <markb@mellanox.com>
    Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
    Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
    Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
    ---
    drivers/infiniband/core/core_priv.h | 2 +-
    drivers/infiniband/core/device.c | 18 ++++++++++++-
    drivers/infiniband/core/nldev.c | 54 ++++++++++++++++++++++++-------------
    3 files changed, 54 insertions(+), 20 deletions(-)

    diff --git a/drivers/infiniband/core/core_priv.h b/drivers/infiniband/core/core_priv.h
    index a1d687a664f8..66f0268f37a6 100644
    --- a/drivers/infiniband/core/core_priv.h
    +++ b/drivers/infiniband/core/core_priv.h
    @@ -314,7 +314,7 @@ static inline int ib_mad_enforce_security(struct ib_mad_agent_private *map,
    }
    #endif

    -struct ib_device *__ib_device_get_by_index(u32 ifindex);
    +struct ib_device *ib_device_get_by_index(u32 ifindex);
    /* RDMA device netlink */
    void nldev_init(void);
    void nldev_exit(void);
    diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
    index 84fc32a2c8b3..f65f64cb8455 100644
    --- a/drivers/infiniband/core/device.c
    +++ b/drivers/infiniband/core/device.c
    @@ -134,7 +134,7 @@ static int ib_device_check_mandatory(struct ib_device *device)
    return 0;
    }

    -struct ib_device *__ib_device_get_by_index(u32 index)
    +static struct ib_device *__ib_device_get_by_index(u32 index)
    {
    struct ib_device *device;

    @@ -145,6 +145,22 @@ struct ib_device *__ib_device_get_by_index(u32 index)
    return NULL;
    }

    +/*
    + * Caller is responsible to return refrerence count by calling put_device()
    + */
    +struct ib_device *ib_device_get_by_index(u32 index)
    +{
    + struct ib_device *device;
    +
    + down_read(&lists_rwsem);
    + device = __ib_device_get_by_index(index);
    + if (device)
    + get_device(&device->dev);
    +
    + up_read(&lists_rwsem);
    + return device;
    +}
    +
    static struct ib_device *__ib_device_get_by_name(const char *name)
    {
    struct ib_device *device;
    diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c
    index 2fae850a3eff..4fbb9681f5cf 100644
    --- a/drivers/infiniband/core/nldev.c
    +++ b/drivers/infiniband/core/nldev.c
    @@ -142,27 +142,34 @@ static int nldev_get_doit(struct sk_buff *skb, struct nlmsghdr *nlh,

    index = nla_get_u32(tb[RDMA_NLDEV_ATTR_DEV_INDEX]);

    - device = __ib_device_get_by_index(index);
    + device = ib_device_get_by_index(index);
    if (!device)
    return -EINVAL;

    msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
    - if (!msg)
    - return -ENOMEM;
    + if (!msg) {
    + err = -ENOMEM;
    + goto err;
    + }

    nlh = nlmsg_put(msg, NETLINK_CB(skb).portid, nlh->nlmsg_seq,
    RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_GET),
    0, 0);

    err = fill_dev_info(msg, device);
    - if (err) {
    - nlmsg_free(msg);
    - return err;
    - }
    + if (err)
    + goto err_free;

    nlmsg_end(msg, nlh);

    + put_device(&device->dev);
    return rdma_nl_unicast(msg, NETLINK_CB(skb).portid);
    +
    +err_free:
    + nlmsg_free(msg);
    +err:
    + put_device(&device->dev);
    + return err;
    }

    static int _nldev_get_dumpit(struct ib_device *device,
    @@ -220,31 +227,40 @@ static int nldev_port_get_doit(struct sk_buff *skb, struct nlmsghdr *nlh,
    return -EINVAL;

    index = nla_get_u32(tb[RDMA_NLDEV_ATTR_DEV_INDEX]);
    - device = __ib_device_get_by_index(index);
    + device = ib_device_get_by_index(index);
    if (!device)
    return -EINVAL;

    port = nla_get_u32(tb[RDMA_NLDEV_ATTR_PORT_INDEX]);
    - if (!rdma_is_port_valid(device, port))
    - return -EINVAL;
    + if (!rdma_is_port_valid(device, port)) {
    + err = -EINVAL;
    + goto err;
    + }

    msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
    - if (!msg)
    - return -ENOMEM;
    + if (!msg) {
    + err = -ENOMEM;
    + goto err;
    + }

    nlh = nlmsg_put(msg, NETLINK_CB(skb).portid, nlh->nlmsg_seq,
    RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_GET),
    0, 0);

    err = fill_port_info(msg, device, port);
    - if (err) {
    - nlmsg_free(msg);
    - return err;
    - }
    + if (err)
    + goto err_free;

    nlmsg_end(msg, nlh);
    + put_device(&device->dev);

    return rdma_nl_unicast(msg, NETLINK_CB(skb).portid);
    +
    +err_free:
    + nlmsg_free(msg);
    +err:
    + put_device(&device->dev);
    + return err;
    }

    static int nldev_port_get_dumpit(struct sk_buff *skb,
    @@ -265,7 +281,7 @@ static int nldev_port_get_dumpit(struct sk_buff *skb,
    return -EINVAL;

    ifindex = nla_get_u32(tb[RDMA_NLDEV_ATTR_DEV_INDEX]);
    - device = __ib_device_get_by_index(ifindex);
    + device = ib_device_get_by_index(ifindex);
    if (!device)
    return -EINVAL;

    @@ -299,7 +315,9 @@ static int nldev_port_get_dumpit(struct sk_buff *skb,
    nlmsg_end(skb, nlh);
    }

    -out: cb->args[0] = idx;
    +out:
    + put_device(&device->dev);
    + cb->args[0] = idx;
    return skb->len;
    }

    --
    2.11.0
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