Re: [PATCH v3 02/11] platform/x86/intel/pmt: crashlog binary file endpoint

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

On Thu, 2025-06-05 at 14:44 -0400, Michael J. Ruhl wrote:
> Usage of the intel_pmt_read() for binary sysfs, requires an allocated
> endpoint struct. The crashlog driver does not allocate the endpoint.
> 
> Without the ep, the crashlog usage causes the following NULL pointer
> exception:
> 
> BUG: kernel NULL pointer dereference, address: 0000000000000000

Okay, there it is. I'll still review the rest to see if the endpoint is even
needed, but if not then you could drop this patch too.

David

> 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
> 
> Add the endpoint information to the crashlog driver to avoid the NULL
> pointer exception.
> 
> 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/crashlog.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/platform/x86/intel/pmt/crashlog.c
> b/drivers/platform/x86/intel/pmt/crashlog.c
> index 6a9eb3c4b313..74ce199e59f0 100644
> --- a/drivers/platform/x86/intel/pmt/crashlog.c
> +++ b/drivers/platform/x86/intel/pmt/crashlog.c
> @@ -252,6 +252,7 @@ static struct intel_pmt_namespace pmt_crashlog_ns = {
>  	.xa = &crashlog_array,
>  	.attr_grp = &pmt_crashlog_group,
>  	.pmt_header_decode = pmt_crashlog_header_decode,
> +	.pmt_add_endpoint = intel_pmt_add_endpoint,
>  };
>  
>  /*
> @@ -262,8 +263,12 @@ static void pmt_crashlog_remove(struct auxiliary_device
> *auxdev)
>  	struct pmt_crashlog_priv *priv = auxiliary_get_drvdata(auxdev);
>  	int i;
>  
> -	for (i = 0; i < priv->num_entries; i++)
> -		intel_pmt_dev_destroy(&priv->entry[i].entry,
> &pmt_crashlog_ns);
> +	for (i = 0; i < priv->num_entries; i++) {
> +		struct intel_pmt_entry *entry = &priv->entry[i].entry;
> +
> +		intel_pmt_release_endpoint(entry->ep);
> +		intel_pmt_dev_destroy(entry, &pmt_crashlog_ns);
> +	}
>  }
>  
>  static int pmt_crashlog_probe(struct auxiliary_device *auxdev,