[PATCH net v3 2/2] pds_core: fix use-after-free on workqueue during remove
From: Nikhil P. Rao <hidden>
Date: 2026-07-14 18:10:36
Subsystem:
amd pds core driver, networking drivers, the rest · Maintainers:
Brett Creeley, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
In pdsc_remove(), the workqueue is destroyed before pdsc_teardown()
is called. This ordering allows two paths to queue work on the
destroyed workqueue:
1. If pdsc_teardown() -> pdsc_devcmd_reset() times out, the error
path in pdsc_devcmd_locked() queues health_work.
2. A NotifyQ event can trigger the ISR and queue work before free_irq()
is called in pdsc_teardown().
Fix by moving destroy_workqueue() after pdsc_teardown() so the
workqueue outlives every queuer; destroy_workqueue() then flushes any
work still pending.
Draining the queued work also requires ordering the teardown so the
resources that work touches are freed last:
- In pdsc_qcq_free(), after freeing the interrupt, cancel_work_sync()
the queue's work and only then clear qcq->intx, so
pdsc_process_adminq()'s read of qcq->intx for interrupt-credit
return cannot race with the clear.
- Free adminqcq before notifyqcq: the shared adminq ISR is released
when adminqcq is freed, and the adminq work accesses notifyqcq, so
both must be stopped before notifyqcq is freed.
Fixes: 01ba61b55b20 ("pds_core: Add adminq processing and commands")
Reported-by: sashiko-bot <sashiko-bot@kernel.org>
Closes: https://patchwork.kernel.org/comment/27002369/
Signed-off-by: Nikhil P. Rao <redacted>
---
drivers/net/ethernet/amd/pds_core/core.c | 14 ++++++++++----
drivers/net/ethernet/amd/pds_core/main.c | 5 +++--
2 files changed, 13 insertions(+), 6 deletions(-)
diff --git a/drivers/net/ethernet/amd/pds_core/core.c b/drivers/net/ethernet/amd/pds_core/core.c
index 1074a022a52f..e39b2c9beb20 100644
--- a/drivers/net/ethernet/amd/pds_core/core.c
+++ b/drivers/net/ethernet/amd/pds_core/core.c@@ -110,7 +110,6 @@ static void pdsc_qcq_intr_free(struct pdsc *pdsc, struct pdsc_qcq *qcq) return; pdsc_intr_free(pdsc, qcq->intx); - qcq->intx = PDS_CORE_INTR_INDEX_NOT_ASSIGNED; } static int pdsc_qcq_intr_alloc(struct pdsc *pdsc, struct pdsc_qcq *qcq)
@@ -145,6 +144,12 @@ void pdsc_qcq_free(struct pdsc *pdsc, struct pdsc_qcq *qcq) pdsc_qcq_intr_free(pdsc, qcq); + /* Drain any work queued by ISR before it was freed above */ + if (qcq->work.func) + cancel_work_sync(&qcq->work); + + qcq->intx = PDS_CORE_INTR_INDEX_NOT_ASSIGNED; + if (qcq->q_base) dma_free_coherent(dev, qcq->q_size, qcq->q_base, qcq->q_base_pa);
@@ -304,8 +309,11 @@ int pdsc_qcq_alloc(struct pdsc *pdsc, unsigned int type, unsigned int index, static void pdsc_core_uninit(struct pdsc *pdsc) { - pdsc_qcq_free(pdsc, &pdsc->notifyqcq); + /* Free adminqcq first: its work accesses notifyqcq, so we must + * disable its IRQ and drain its work before freeing notifyqcq. + */ pdsc_qcq_free(pdsc, &pdsc->adminqcq); + pdsc_qcq_free(pdsc, &pdsc->notifyqcq); if (pdsc->kern_dbpage) { iounmap(pdsc->kern_dbpage);
@@ -479,8 +487,6 @@ void pdsc_teardown(struct pdsc *pdsc, bool removing) { if (!pdsc->pdev->is_virtfn) pdsc_devcmd_reset(pdsc); - if (pdsc->adminqcq.work.func) - cancel_work_sync(&pdsc->adminqcq.work); pci_clear_master(pdsc->pdev);
diff --git a/drivers/net/ethernet/amd/pds_core/main.c b/drivers/net/ethernet/amd/pds_core/main.c
index 22db78343eb0..638b9c7a509d 100644
--- a/drivers/net/ethernet/amd/pds_core/main.c
+++ b/drivers/net/ethernet/amd/pds_core/main.c@@ -435,8 +435,6 @@ static void pdsc_remove(struct pci_dev *pdev) pdsc_auxbus_dev_del(pdsc, pdsc, &pdsc->padev); timer_shutdown_sync(&pdsc->wdtimer); - if (pdsc->wq) - destroy_workqueue(pdsc->wq); mutex_lock(&pdsc->config_lock); set_bit(PDSC_S_STOPPING_DRIVER, &pdsc->state);
@@ -444,6 +442,9 @@ static void pdsc_remove(struct pci_dev *pdev) pdsc_stop(pdsc); pdsc_teardown(pdsc, PDSC_TEARDOWN_REMOVING); mutex_unlock(&pdsc->config_lock); + + if (pdsc->wq) + destroy_workqueue(pdsc->wq); mutex_destroy(&pdsc->config_lock); mutex_destroy(&pdsc->devcmd_lock);
--
2.43.0