FAILED: patch "[PATCH] ACPI: NFIT: core: Fix acpi_nfit_init() error cleanup" failed to apply to 6.1-stable tree

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 38bf27511ef41bffebd157ec3eba41fc89ba59cd
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026070917-boring-spirited-9fa8@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 38bf27511ef41bffebd157ec3eba41fc89ba59cd Mon Sep 17 00:00:00 2001
From: "Rafael J. Wysocki" <[email protected]>
Date: Wed, 3 Jun 2026 19:57:02 +0200
Subject: [PATCH] ACPI: NFIT: core: Fix acpi_nfit_init() error cleanup

If acpi_nfit_init() fails after adding the acpi_desc object to the acpi_descs list, that object is never removed from that list because the acpi_nfit_shutdown() devm action is not added for the NFIT device in that case. Next, the acpi_nfit_init() failure causes acpi_nfit_probe() to fail, the acpi_desc object is freed, and a dangling pointer is left behind in the acpi_descs. Any subsequent ACPI Machine Check Exception will trigger nfit_handle_mce() which iterates over acpi_descs and so a use-after-free will occur.

Moreover, if acpi_nfit_probe() returns 0 after installing a notify handler for the NFIT device and without allocating the acpi_desc object and setting the NFIT device's driver data pointer, the acpi_desc object will be allocated by acpi_nfit_update_notify() and acpi_nfit_init() will be called to initialize it. Regardless of whether or not acpi_nfit_init() fails in that case, the acpi_nfit_shutdown() devm action is not added for the NFIT device and acpi_desc is never removed from the acpi_descs list. If the acpi_desc object is freed subsequently on driver removal, any subsequent ACPI MCE will lead to a use-after-free like in the previous case.

To address the first issue mentioned above, make acpi_nfit_probe() call acpi_nfit_shutdown() directly on acpi_nfit_init() failures and to address the other one, add a remove callback to the driver and make it call acpi_nfit_shutdown(). Also, since it is now possible to pass NULL to acpi_nfit_shutdown() or the acpi_desc object passed to it may not have been initialized, add checks against NULL for acpi_desc and its nvdimm_bus field to that function and make acpi_nfit_unregister() clear the latter after unregistering the NVDIMM bus.

index 8024cd3cad14..01c73be0bd00 100644
@@ -3069,6 +3069,8 @@ static void acpi_nfit_unregister(void *data)
 	struct acpi_nfit_desc *acpi_desc = data;
 
 	nvdimm_bus_unregister(acpi_desc->nvdimm_bus);
+	/* The nvdimm_bus object may have been freed, so clear the pointer. */
+	acpi_desc->nvdimm_bus = NULL;
 }
 
 int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, void *data, acpi_size sz)

@@ -3301,7 +3303,10 @@ static void acpi_nfit_notify(acpi_handle handle, u32 event, void *data)
 void acpi_nfit_shutdown(void *data)
 {
 	struct acpi_nfit_desc *acpi_desc = data;
-	struct device *bus_dev = to_nvdimm_bus_dev(acpi_desc->nvdimm_bus);
+	struct device *bus_dev;
+
+	if (!acpi_desc || !acpi_desc->nvdimm_bus)
+		return;
 
 	/*
 	 * Destruct under acpi_desc_lock so that nfit_handle_mce does not

@@ -3316,6 +3321,7 @@ void acpi_nfit_shutdown(void *data)
 	mutex_unlock(&acpi_desc->init_mutex);
 	cancel_delayed_work_sync(&acpi_desc->dwork);
 
+	bus_dev = to_nvdimm_bus_dev(acpi_desc->nvdimm_bus);
 	/*
 	 * Bounce the nvdimm bus lock to make sure any in-flight
 	 * acpi_nfit_ars_rescan() submissions have had a chance to

@@ -3388,9 +3394,14 @@ static int acpi_nfit_probe(struct platform_device *pdev)
 				sz - sizeof(struct acpi_table_nfit));
 
 	if (rc)
-		return rc;
+		acpi_nfit_shutdown(acpi_desc);
 
-	return devm_add_action_or_reset(dev, acpi_nfit_shutdown, acpi_desc);
+	return rc;
+}
+
+static void acpi_nfit_remove(struct platform_device *pdev)
+{
+	acpi_nfit_shutdown(platform_get_drvdata(pdev));
 }
 
 static void acpi_nfit_update_notify(struct device *dev, acpi_handle handle)

@@ -3474,6 +3485,7 @@ MODULE_DEVICE_TABLE(acpi, acpi_nfit_ids);
 
 static struct platform_driver acpi_nfit_driver = {
 	.probe = acpi_nfit_probe,
+	.remove = acpi_nfit_remove,
 	.driver = {
 		.name = "acpi-nfit",
 		.acpi_match_table = acpi_nfit_ids,

From: "Rafael J. Wysocki" <[email protected]>

[ Upstream commit 38bf27511ef41bffebd157ec3eba41fc89ba59cd ]

If acpi_nfit_init() fails after adding the acpi_desc object to the acpi_descs list, that object is never removed from that list because the acpi_nfit_shutdown() devm action is not added for the NFIT device in that case. Next, the acpi_nfit_init() failure causes acpi_nfit_probe() to fail, the acpi_desc object is freed, and a dangling pointer is left behind in the acpi_descs. Any subsequent ACPI Machine Check Exception will trigger nfit_handle_mce() which iterates over acpi_descs and so a use-after-free will occur.

Moreover, if acpi_nfit_probe() returns 0 after installing a notify handler for the NFIT device and without allocating the acpi_desc object and setting the NFIT device's driver data pointer, the acpi_desc object will be allocated by acpi_nfit_update_notify() and acpi_nfit_init() will be called to initialize it. Regardless of whether or not acpi_nfit_init() fails in that case, the acpi_nfit_shutdown() devm action is not added for the NFIT device and acpi_desc is never removed from the acpi_descs list. If the acpi_desc object is freed subsequently on driver removal, any subsequent ACPI MCE will lead to a use-after-free like in the previous case.

To address the first issue mentioned above, make acpi_nfit_probe() call acpi_nfit_shutdown() directly on acpi_nfit_init() failures and to address the other one, add a remove callback to the driver and make it call acpi_nfit_shutdown(). Also, since it is now possible to pass NULL to acpi_nfit_shutdown() or the acpi_desc object passed to it may not have been initialized, add checks against NULL for acpi_desc and its nvdimm_bus field to that function and make acpi_nfit_unregister() clear the latter after unregistering the NVDIMM bus.

---
 drivers/acpi/nfit/core.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

index 78c9f56b4ba341..00490c2e4d08c4 100644
@@ -3067,6 +3067,8 @@ static void acpi_nfit_unregister(void *data)
 	struct acpi_nfit_desc *acpi_desc = data;
 
 	nvdimm_bus_unregister(acpi_desc->nvdimm_bus);
+	/* The nvdimm_bus object may have been freed, so clear the pointer. */
+	acpi_desc->nvdimm_bus = NULL;
 }
 
 int acpi_nfit_init(struct acpi_nfit_desc *acpi_desc, void *data, acpi_size sz)

@@ -3290,7 +3292,10 @@ static void acpi_nfit_put_table(void *table)
 void acpi_nfit_shutdown(void *data)
 {
 	struct acpi_nfit_desc *acpi_desc = data;
-	struct device *bus_dev = to_nvdimm_bus_dev(acpi_desc->nvdimm_bus);
+	struct device *bus_dev;
+
+	if (!acpi_desc || !acpi_desc->nvdimm_bus)
+		return;
 
 	/*
 	 * Destruct under acpi_desc_lock so that nfit_handle_mce does not

@@ -3305,6 +3310,7 @@ void acpi_nfit_shutdown(void *data)
 	mutex_unlock(&acpi_desc->init_mutex);
 	cancel_delayed_work_sync(&acpi_desc->dwork);
 
+	bus_dev = to_nvdimm_bus_dev(acpi_desc->nvdimm_bus);
 	/*
 	 * Bounce the nvdimm bus lock to make sure any in-flight
 	 * acpi_nfit_ars_rescan() submissions have had a chance to

@@ -3372,13 +3378,14 @@ static int acpi_nfit_add(struct acpi_device *adev)
 				sz - sizeof(struct acpi_table_nfit));
 
 	if (rc)
-		return rc;
-	return devm_add_action_or_reset(dev, acpi_nfit_shutdown, acpi_desc);
+		acpi_nfit_shutdown(acpi_desc);
+
+	return rc;
 }
 
 static int acpi_nfit_remove(struct acpi_device *adev)
 {
-	/* see acpi_nfit_unregister */
+	acpi_nfit_shutdown(dev_get_drvdata(&adev->dev));
 	return 0;
 }
 

2.53.0