On Fri, 27 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
Can you confirm, if this was possible to trigger only after this series
has been applied, not with the current mainline code?
--
i.
> Augment struct intel_pmt_entry with a pointer to the pcidev to avoid
> the NULL pointer exception.
>
> Reviewed-by: Tejas Upadhyay
tejas.upadhyay@intel.com
> Fixes: 416eeb2e1fc7 ("platform/x86/intel/pmt: telemetry: Export API to read telemetry")
> Cc:
stable@vger.kernel.org
> Signed-off-by: Michael J. Ruhl
michael.j.ruhl@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;
>
