[PATCH v4 01/10] platform/x86/intel/pmt: fix a crashlog NULL pointer access

[Ruhl, Michael J]

>-----Original Message-----
>From: Ilpo Järvinen <ilpo.jarvinen at linux.intel.com>
>Sent: Wednesday, June 11, 2025 6:42 AM
>To: Ruhl, Michael J <michael.j.ruhl at intel.com>
>Cc: platform-driver-x86 at vger.kernel.org; intel-xe at lists.freedesktop.org; Hans
>de Goede <hdegoede at redhat.com>; De Marchi, Lucas
><lucas.demarchi at intel.com>; Vivi, Rodrigo <rodrigo.vivi at intel.com>;
>thomas.hellstrom at linux.intel.com; airlied at gmail.com; simona at ffwll.ch;
>david.e.box at linux.intel.com; stable at vger.kernel.org
>Subject: Re: [PATCH v4 01/10] platform/x86/intel/pmt: fix a crashlog NULL
>pointer access
>
>On Tue, 10 Jun 2025, Michael J. Ruhl wrote:
>
>> 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 the inte_pmt_entry to include the pcidev to allow for access to
>
>intel_pmt_entry

I have also been told that should be "intel_pmt_entry()"....  when I redo, is that
more correct?

Thanks,

M

>> the pcidev and avoid the NULL pointer exception.
>>
>> Fixes: 416eeb2e1fc7 ("platform/x86/intel/pmt: telemetry: Export API to read
>telemetry")
>> Cc: <stable at vger.kernel.org>
>> Signed-off-by: Michael J. Ruhl <michael.j.ruhl at intel.com>
>> ---
>>  drivers/platform/x86/intel/pmt/class.c | 3 ++-
>>  drivers/platform/x86/intel/pmt/class.h | 1 +
>>  2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/platform/x86/intel/pmt/class.c
>b/drivers/platform/x86/intel/pmt/class.c
>> index 7233b654bbad..d046e8752173 100644
>> --- a/drivers/platform/x86/intel/pmt/class.c
>> +++ b/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;
>> diff --git a/drivers/platform/x86/intel/pmt/class.h
>b/drivers/platform/x86/intel/pmt/class.h
>> index b2006d57779d..f6ce80c4e051 100644
>> --- a/drivers/platform/x86/intel/pmt/class.h
>> +++ b/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;
>>
>
>--
> i.