This is a note to let you know that I've just added the patch titled
PCI: switchtec: Fix stdev_release() crash after surprise hot remove
to the 6.1-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
pci-switchtec-fix-stdev_release-crash-after-surprise.patch
and it can be found in the queue-6.1 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c979716ecafadc0a2400e47ed84e8d762a4f4e4b
Author: Daniel Stodden <dns@xxxxxxxxxx>
Date: Tue Nov 21 20:23:16 2023 -0800
PCI: switchtec: Fix stdev_release() crash after surprise hot remove
[ Upstream commit df25461119d987b8c81d232cfe4411e91dcabe66 ]
A PCI device hot removal may occur while stdev->cdev is held open. The call
to stdev_release() then happens during close or exit, at a point way past
switchtec_pci_remove(). Otherwise the last ref would vanish with the
trailing put_device(), just before return.
At that later point in time, the devm cleanup has already removed the
stdev->mmio_mrpc mapping. Also, the stdev->pdev reference was not a counted
one. Therefore, in DMA mode, the iowrite32() in stdev_release() will cause
a fatal page fault, and the subsequent dma_free_coherent(), if reached,
would pass a stale &stdev->pdev->dev pointer.
Fix by moving MRPC DMA shutdown into switchtec_pci_remove(), after
stdev_kill(). Counting the stdev->pdev ref is now optional, but may prevent
future accidents.
Reproducible via the script at
https://lore.kernel.org/r/20231113212150.96410-1-dns@xxxxxxxxxx
Link: https://lore.kernel.org/r/20231122042316.91208-2-dns@xxxxxxxxxx
Signed-off-by: Daniel Stodden <dns@xxxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
Reviewed-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Reviewed-by: Dmitry Safonov <dima@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
index 0c1faa6c1973..3f3320d0a4f8 100644
--- a/drivers/pci/switch/switchtec.c
+++ b/drivers/pci/switch/switchtec.c
@@ -1308,13 +1308,6 @@ static void stdev_release(struct device *dev)
{
struct switchtec_dev *stdev = to_stdev(dev);
- if (stdev->dma_mrpc) {
- iowrite32(0, &stdev->mmio_mrpc->dma_en);
- flush_wc_buf(stdev);
- writeq(0, &stdev->mmio_mrpc->dma_addr);
- dma_free_coherent(&stdev->pdev->dev, sizeof(*stdev->dma_mrpc),
- stdev->dma_mrpc, stdev->dma_mrpc_dma_addr);
- }
kfree(stdev);
}
@@ -1358,7 +1351,7 @@ static struct switchtec_dev *stdev_create(struct pci_dev *pdev)
return ERR_PTR(-ENOMEM);
stdev->alive = true;
- stdev->pdev = pdev;
+ stdev->pdev = pci_dev_get(pdev);
INIT_LIST_HEAD(&stdev->mrpc_queue);
mutex_init(&stdev->mrpc_mutex);
stdev->mrpc_busy = 0;
@@ -1391,6 +1384,7 @@ static struct switchtec_dev *stdev_create(struct pci_dev *pdev)
return stdev;
err_put:
+ pci_dev_put(stdev->pdev);
put_device(&stdev->dev);
return ERR_PTR(rc);
}
@@ -1646,6 +1640,18 @@ static int switchtec_init_pci(struct switchtec_dev *stdev,
return 0;
}
+static void switchtec_exit_pci(struct switchtec_dev *stdev)
+{
+ if (stdev->dma_mrpc) {
+ iowrite32(0, &stdev->mmio_mrpc->dma_en);
+ flush_wc_buf(stdev);
+ writeq(0, &stdev->mmio_mrpc->dma_addr);
+ dma_free_coherent(&stdev->pdev->dev, sizeof(*stdev->dma_mrpc),
+ stdev->dma_mrpc, stdev->dma_mrpc_dma_addr);
+ stdev->dma_mrpc = NULL;
+ }
+}
+
static int switchtec_pci_probe(struct pci_dev *pdev,
const struct pci_device_id *id)
{
@@ -1705,6 +1711,9 @@ static void switchtec_pci_remove(struct pci_dev *pdev)
ida_free(&switchtec_minor_ida, MINOR(stdev->dev.devt));
dev_info(&stdev->dev, "unregistered.\n");
stdev_kill(stdev);
+ switchtec_exit_pci(stdev);
+ pci_dev_put(stdev->pdev);
+ stdev->pdev = NULL;
put_device(&stdev->dev);
}
