Overview
About vulnerability
In the Linux kernel, the following vulnerability has been resolved:
RDMA/iwcm: Fix WARNING:at_kernel/workqueue.c:#check_flush_dependency
In the commit aee2424246f9 (“RDMA/iwcm: Fix a use-after-free related to destroying CM IDs”), the function flush_workqueue is invoked to flush the work queue iwcm_wq.
But at that time, the work queue iwcm_wq was created via the function alloc_ordered_workqueue without the flag WQ_MEM_RECLAIM.
Because the current process is trying to flush the whole iwcm_wq, if iwcm_wq doesn’t have the flag WQ_MEM_RECLAIM, verify that the current process is not reclaiming memory or running on a workqueue which doesn’t have the flag WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to a deadlock.
The call trace is as below:
[ 125.350876][ T1430] Call Trace:
[ 125.356281][ T1430]
Details
- Affected product:
- Ubuntu 16.04 ELS , Ubuntu 18.04 ELS
- Affected packages:
- linux-hwe @ 4.15.0 (+1 more)
In the Linux kernel, the following vulnerability has been resolved:
RDMA/iwcm: Fix WARNING:at_kernel/workqueue.c:#check_flush_dependency
In the commit aee2424246f9 (“RDMA/iwcm: Fix a use-after-free related to destroying CM IDs”), the function flush_workqueue is invoked to flush the work queue iwcm_wq.
But at that time, the work queue iwcm_wq was created via the function alloc_ordered_workqueue without the flag WQ_MEM_RECLAIM.
Because the current process is trying to flush the whole iwcm_wq, if iwcm_wq doesn’t have the flag WQ_MEM_RECLAIM, verify that the current process is not reclaiming memory or running on a workqueue which doesn’t have the flag WQ_MEM_RECLAIM as that can break forward-progress guarantee leading to a deadlock.
The call trace is as below:
[ 125.350876][ T1430] Call Trace:
[ 125.356281][ T1430]