Re: [PATCH for-rc] RDMA/srpt: Fix UAF when srpt_add_one() failed

[Leon Romanovsky <leon@kernel.org>]

On Thu, Aug 01, 2024 at 03:44:15PM +0800, Junxian Huang wrote:
> Currently cancel_work_sync() is not called when srpt_refresh_port()
> failed in srpt_add_one(). There is a probability that sdev has been
> freed while the previously initiated sport->work is still running,
> leading to a UAF as the log below:
> 
> [  T880] ib_srpt MAD registration failed for hns_1-1.
> [  T880] ib_srpt srpt_add_one(hns_1) failed.
> [  T376] Unable to handle kernel paging request at virtual address 0000000000010008
> ...
> [  T376] Workqueue: events srpt_refresh_port_work [ib_srpt]
> ...
> [  T376] Call trace:
> [  T376]  srpt_refresh_port+0x94/0x264 [ib_srpt]
> [  T376]  srpt_refresh_port_work+0x1c/0x2c [ib_srpt]
> [  T376]  process_one_work+0x1d8/0x4cc
> [  T376]  worker_thread+0x158/0x410
> [  T376]  kthread+0x108/0x13c
> [  T376]  ret_from_fork+0x10/0x18
> 
> Add cancel_work_sync() to the exception branch to fix this UAF.
> 
> Fixes: a42d985bd5b2 ("ib_srpt: Initial SRP Target merge for v3.3-rc1")
> Signed-off-by: Junxian Huang <huangjunxian6@hisilicon.com>
> ---
>  drivers/infiniband/ulp/srpt/ib_srpt.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
> index 9632afbd727b..244e5c115bf7 100644
> --- a/drivers/infiniband/ulp/srpt/ib_srpt.c
> +++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
> @@ -3148,8 +3148,8 @@ static int srpt_add_one(struct ib_device *device)
>  {
>  	struct srpt_device *sdev;
>  	struct srpt_port *sport;
> +	u32 i, j;
>  	int ret;
> -	u32 i;
>  
>  	pr_debug("device = %p\n", device);
>  
> @@ -3226,7 +3226,6 @@ static int srpt_add_one(struct ib_device *device)
>  		if (ret) {
>  			pr_err("MAD registration failed for %s-%d.\n",
>  			       dev_name(&sdev->device->dev), i);
> -			i--;
>  			goto err_port;
>  		}
>  	}
> @@ -3241,6 +3240,8 @@ static int srpt_add_one(struct ib_device *device)
>  	return 0;
>  
>  err_port:
> +	for (j = i, i--; j > 0; j--)a
> +		cancel_work_sync(&sdev->port[j - 1].work);

There is no need in extra variable, the following code will do the same:

	while (i--)
		cancel_work_sync(&sdev->port[i].work);

>  	srpt_unregister_mad_agent(sdev, i);
>  err_cm:
>  	if (sdev->cm_id)
> -- 
> 2.33.0
>