Re: [PATCH v2] RDMA/nldev: Fix NULL pointer dereferences issue in rdma_nl_notify_event

[Jason Gunthorpe <jgg@nvidia.com>]

On Fri, Sep 27, 2024 at 10:06:13PM +0800, Qianqiang Liu wrote:
> nlmsg_put() may return a NULL pointer assigned to nlh, which will later
> be dereferenced in nlmsg_end().
> 
> Fixes: 9cbed5aab5ae ("RDMA/nldev: Add support for RDMA monitoring")
> Signed-off-by: Qianqiang Liu <qianqiang.liu@163.com>
> ---
>  Changes since v1:
>  - Add Fixes tag
> ---
>  drivers/infiniband/core/nldev.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/infiniband/core/nldev.c b/drivers/infiniband/core/nldev.c
> index 39f89a4b86498..7dc8e2ec62cc8 100644
> --- a/drivers/infiniband/core/nldev.c
> +++ b/drivers/infiniband/core/nldev.c
> @@ -2816,6 +2816,8 @@ int rdma_nl_notify_event(struct ib_device *device, u32 port_num,
>  	nlh = nlmsg_put(skb, 0, 0,
>  			RDMA_NL_GET_TYPE(RDMA_NL_NLDEV, RDMA_NLDEV_CMD_MONITOR),
>  			0, 0);
> +	if (!nlh)
> +		goto err_free;

It doesn't look to me like nlmsg_put can fail in this usage, but we
should probbaly put the if to avoid getting static checkers warning on
it.

Applied to for-rc, thanks

Jason