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Ruhl" cc: platform-driver-x86@vger.kernel.org, intel-xe@lists.freedesktop.org, Hans de Goede , lucas.demarchi@intel.com, rodrigo.vivi@intel.com, thomas.hellstrom@linux.intel.com, airlied@gmail.com, simona@ffwll.ch, david.e.box@linux.intel.com, stable@vger.kernel.org Subject: Re: [PATCH v4 01/10] platform/x86/intel/pmt: fix a crashlog NULL pointer access In-Reply-To: <20250610211225.1085901-2-michael.j.ruhl@intel.com> Message-ID: References: <20250610211225.1085901-1-michael.j.ruhl@intel.com> <20250610211225.1085901-2-michael.j.ruhl@intel.com> Precedence: bulk X-Mailing-List: platform-driver-x86@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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: > > ? 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 > the pcidev and avoid the NULL pointer exception. > > Fixes: 416eeb2e1fc7 ("platform/x86/intel/pmt: telemetry: Export API to read telemetry") > Cc: > Signed-off-by: Michael J. Ruhl > --- > 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.