platform/x86/intel/pmt: fix a crashlog NULL pointer access

commit 54d5cd4 upstream.

Usage of the intel_pmt_read() for binary sysfs, requires a pcidev. The
current use of the endpoint value is only valid for telemetry endpoint
usage.

Without the ep, the crashlog usage causes the following NULL pointer
exception:

BUG: kernel NULL pointer dereference, address: 0000000000000000
Oops: Oops: 0000 [#1] SMP NOPTI
RIP: 0010:intel_pmt_read+0x3b/0x70 [pmt_class]
Code:
Call Trace:
 <TASK>
 ? sysfs_kf_bin_read+0xc0/0xe0
 kernfs_fop_read_iter+0xac/0x1a0
 vfs_read+0x26d/0x350
 ksys_read+0x6b/0xe0
 __x64_sys_read+0x1d/0x30
 x64_sys_call+0x1bc8/0x1d70
 do_syscall_64+0x6d/0x110

Augment struct intel_pmt_entry with a pointer to the pcidev to avoid
the NULL pointer exception.

Fixes: 045a513 ("platform/x86/intel/pmt: Use PMT callbacks")
Cc: [email protected]
Reviewed-by: David E. Box <[email protected]>
Reviewed-by: Tejas Upadhyay <[email protected]>
Signed-off-by: Michael J. Ruhl <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Ilpo Järvinen <[email protected]>
Signed-off-by: Ilpo Järvinen <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: mjruhl

drivers/platform/x86/intel/pmt/class.c

@@ -97,7 +97,7 @@ 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->pcidev, entry->cb, entry->header.guid, buf,
+	count = pmt_telem_read_mmio(entry->pcidev, entry->cb, entry->header.guid, buf,
 				    entry->base, off, count);
 
 	return count;
@@ -252,6 +252,7 @@ static int intel_pmt_populate_entry(struct intel_pmt_entry *entry,
 		return -EINVAL;
 	}
 
+	entry->pcidev = pci_dev;
 	entry->guid = header->guid;
 	entry->size = header->size;
 	entry->cb = ivdev->priv_data;

drivers/platform/x86/intel/pmt/class.h

@@ -39,6 +39,7 @@ struct intel_pmt_header {
 
 struct intel_pmt_entry {
 	struct telem_endpoint	*ep;
+	struct pci_dev		*pcidev;
 	struct intel_pmt_header	header;
 	struct bin_attribute	pmt_bin_attr;
 	struct kobject		*kobj;