On Fri, Jul 11, 2025 at 01:27:43PM +0100, Giovanni Cabiddu wrote:
Repeated loading and unloading of a device specific QAT driver, for example qat_4xxx, in a tight loop can lead to a crash due to a use-after-free scenario. This occurs when a power management (PM) interrupt triggers just before the device-specific driver (e.g., qat_4xxx.ko) is unloaded, while the core driver (intel_qat.ko) remains loaded.
Since the driver uses a shared workqueue (`qat_misc_wq`) across all devices and owned by intel_qat.ko, a deferred routine from the device-specific driver may still be pending in the queue. If this routine executes after the driver is unloaded, it can dereference freed memory, resulting in a page fault and kernel crash like the following:
BUG: unable to handle page fault for address: ffa000002e50a01c #PF: supervisor read access in kernel mode RIP: 0010:pm_bh_handler+0x1d2/0x250 [intel_qat] Call Trace: pm_bh_handler+0x1d2/0x250 [intel_qat] process_one_work+0x171/0x340 worker_thread+0x277/0x3a0 kthread+0xf0/0x120 ret_from_fork+0x2d/0x50To prevent this, flush the misc workqueue during device shutdown to ensure that all pending work items are completed before the driver is unloaded.
Note: This approach may slightly increase shutdown latency if the workqueue contains jobs from other devices, but it ensures correctness and stability.
Fixes: e5745f34113b ("crypto: qat - enable power management for QAT GEN4") Signed-off-by: Giovanni Cabiddu giovanni.cabiddu@intel.com Cc: stable@vger.kernel.org Reviewed-by: Ahsan Atta ahsan.atta@intel.com
drivers/crypto/intel/qat/qat_common/adf_common_drv.h | 1 + drivers/crypto/intel/qat/qat_common/adf_init.c | 1 + drivers/crypto/intel/qat/qat_common/adf_isr.c | 5 +++++ 3 files changed, 7 insertions(+)
Patch applied. Thanks.