[PATCH 1/3] platform/x86/intel/pmt: Fix NULL dereference when reading crashlog data

["David E. Box" <david.e.box@linux.intel.com>]

Commit 353042d54d82 ("platform/x86/intel/vsec: Switch exported helpers from
pci_dev to device") changed intel_pmt_read() to pass entry->ep->dev to
pmt_telem_read_mmio() in place of entry->pcidev. entry->ep is only
allocated by the telemetry namespace's pmt_add_endpoint() hook. Crashlog
entries never get one, so any read() of a crashlog sysfs data file
dereferences a NULL pointer.

Use the intel_vsec_device parent device instead. The PMT class device is a
child of the auxiliary device, so derive it the same way
intel_pmt_attr_visible() does. This is the same device telemetry stored in
ep->dev, so behavior for telemetry and any read_telem() callback is
unchanged.

Fixes: 353042d54d82 ("platform/x86/intel/vsec: Switch exported helpers from pci_dev to device")
Cc: stable@vger.kernel.org
Assisted-by: LLM
Signed-off-by: David E. Box <david.e.box@linux.intel.com>
---
 drivers/platform/x86/intel/pmt/class.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/platform/x86/intel/pmt/class.c b/drivers/platform/x86/intel/pmt/class.c
index d0ab8e33c62a..b69c79785d9c 100644
--- a/drivers/platform/x86/intel/pmt/class.c
+++ b/drivers/platform/x86/intel/pmt/class.c
@@ -90,6 +90,8 @@ intel_pmt_read(struct file *filp, struct kobject *kobj,
 	struct intel_pmt_entry *entry = container_of(attr,
 						     struct intel_pmt_entry,
 						     pmt_bin_attr);
+	struct device *dev = kobj_to_dev(kobj);
+	struct intel_vsec_device *ivdev = auxdev_to_ivdev(to_auxiliary_dev(dev->parent));
 
 	if (off < 0)
 		return -EINVAL;
@@ -100,7 +102,7 @@ intel_pmt_read(struct file *filp, struct kobject *kobj,
 	if (count > entry->size - off)
 		count = entry->size - off;
 
-	count = pmt_telem_read_mmio(entry->ep->dev, entry->cb, entry->header.guid, buf,
+	count = pmt_telem_read_mmio(ivdev->dev, entry->cb, entry->header.guid, buf,
 				    entry->base, off, count);
 
 	return count;
-- 
2.43.0