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

[Junxian Huang <huangjunxian6@hisilicon.com>]

On 2024/8/1 18:37, Leon Romanovsky wrote:
> 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);

i is also used here.

Junxian

>>  err_cm:
>>  	if (sdev->cm_id)
>> -- 
>> 2.33.0
>>
>