2021-04-02 08:24:01

by Takashi Iwai

Subject: [PATCH v2] drm/i915: Fix invalid access to ACPI _DSM objects

intel_dsm_platform_mux_info() tries to parse the ACPI package data
from _DSM for the debug information, but it assumes the fixed format
without checking what values are stored in the elements actually.
When an unexpected value is returned from BIOS, it may lead to GPF or
NULL dereference, as reported recently.

Add the checks of the contents in the returned values and skip the
values for invalid cases.

v1->v2: Check the info contents before dereferencing, too

BugLink: http://bugzilla.opensuse.org/show_bug.cgi?id=1184074
Cc: <[email protected]>
Signed-off-by: Takashi Iwai <[email protected]>
---
drivers/gpu/drm/i915/display/intel_acpi.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_acpi.c b/drivers/gpu/drm/i915/display/intel_acpi.c
index e21fb14d5e07..833d0c1be4f1 100644
--- a/drivers/gpu/drm/i915/display/intel_acpi.c
+++ b/drivers/gpu/drm/i915/display/intel_acpi.c
@@ -84,13 +84,31 @@ static void intel_dsm_platform_mux_info(acpi_handle dhandle)
return;
}

+ if (!pkg->package.count) {
+ DRM_DEBUG_DRIVER("no connection in _DSM\n");
+ return;
+ }
+
connector_count = &pkg->package.elements[0];
DRM_DEBUG_DRIVER("MUX info connectors: %lld\n",
(unsigned long long)connector_count->integer.value);
for (i = 1; i < pkg->package.count; i++) {
union acpi_object *obj = &pkg->package.elements[i];
- union acpi_object *connector_id = &obj->package.elements[0];
- union acpi_object *info = &obj->package.elements[1];
+ union acpi_object *connector_id;
+ union acpi_object *info;
+
+ if (obj->type != ACPI_TYPE_PACKAGE || obj->package.count < 2) {
+ DRM_DEBUG_DRIVER("Invalid object for MUX #%d\n", i);
+ continue;
+ }
+
+ connector_id = &obj->package.elements[0];
+ info = &obj->package.elements[1];
+ if (info->type != ACPI_TYPE_BUFFER || info->buffer.length < 4) {
+ DRM_DEBUG_DRIVER("Invalid info for MUX obj #%d\n", i);
+ continue;
+ }
+
DRM_DEBUG_DRIVER("Connector id: 0x%016llx\n",
(unsigned long long)connector_id->integer.value);
DRM_DEBUG_DRIVER(" port id: %s\n",
--
2.26.2

2021-04-07 22:41:04

by Ville Syrjälä

Subject: Re: [Intel-gfx] [PATCH v2] drm/i915: Fix invalid access to ACPI _DSM objects

On Fri, Apr 02, 2021 at 10:23:17AM +0200, Takashi Iwai wrote:
> intel_dsm_platform_mux_info() tries to parse the ACPI package data
> from _DSM for the debug information, but it assumes the fixed format
> without checking what values are stored in the elements actually.
> When an unexpected value is returned from BIOS, it may lead to GPF or
> NULL dereference, as reported recently.
>
> Add the checks of the contents in the returned values and skip the
> values for invalid cases.
>
> v1->v2: Check the info contents before dereferencing, too
>
> BugLink: http://bugzilla.opensuse.org/show_bug.cgi?id=1184074
> Cc: <[email protected]>
> Signed-off-by: Takashi Iwai <[email protected]>
> ---
> drivers/gpu/drm/i915/display/intel_acpi.c | 22 ++++++++++++++++++++--
> 1 file changed, 20 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_acpi.c b/drivers/gpu/drm/i915/display/intel_acpi.c
> index e21fb14d5e07..833d0c1be4f1 100644
> --- a/drivers/gpu/drm/i915/display/intel_acpi.c
> +++ b/drivers/gpu/drm/i915/display/intel_acpi.c
> @@ -84,13 +84,31 @@ static void intel_dsm_platform_mux_info(acpi_handle dhandle)
> return;
> }
>
> + if (!pkg->package.count) {
> + DRM_DEBUG_DRIVER("no connection in _DSM\n");
> + return;
> + }
> +
> connector_count = &pkg->package.elements[0];
> DRM_DEBUG_DRIVER("MUX info connectors: %lld\n",
> (unsigned long long)connector_count->integer.value);
> for (i = 1; i < pkg->package.count; i++) {
> union acpi_object *obj = &pkg->package.elements[i];
> - union acpi_object *connector_id = &obj->package.elements[0];
> - union acpi_object *info = &obj->package.elements[1];
> + union acpi_object *connector_id;
> + union acpi_object *info;
> +
> + if (obj->type != ACPI_TYPE_PACKAGE || obj->package.count < 2) {
> + DRM_DEBUG_DRIVER("Invalid object for MUX #%d\n", i);
> + continue;
> + }
> +
> + connector_id = &obj->package.elements[0];

You don't want to check connector_id->type as well?

> + info = &obj->package.elements[1];
> + if (info->type != ACPI_TYPE_BUFFER || info->buffer.length < 4) {
> + DRM_DEBUG_DRIVER("Invalid info for MUX obj #%d\n", i);
> + continue;
> + }
> +
> DRM_DEBUG_DRIVER("Connector id: 0x%016llx\n",
> (unsigned long long)connector_id->integer.value);
> DRM_DEBUG_DRIVER(" port id: %s\n",
> --
> 2.26.2
>
> _______________________________________________
> Intel-gfx mailing list
> [email protected]
> https://lists.freedesktop.org/mailman/listinfo/intel-gfx

--
Ville Syrj?l?
Intel

2021-04-07 22:41:32

by Takashi Iwai

Subject: Re: [Intel-gfx] [PATCH v2] drm/i915: Fix invalid access to ACPI _DSM objects

On Wed, 07 Apr 2021 18:34:46 +0200,
Ville Syrjälä wrote:
>
> On Fri, Apr 02, 2021 at 10:23:17AM +0200, Takashi Iwai wrote:
> > intel_dsm_platform_mux_info() tries to parse the ACPI package data
> > from _DSM for the debug information, but it assumes the fixed format
> > without checking what values are stored in the elements actually.
> > When an unexpected value is returned from BIOS, it may lead to GPF or
> > NULL dereference, as reported recently.
> >
> > Add the checks of the contents in the returned values and skip the
> > values for invalid cases.
> >
> > v1->v2: Check the info contents before dereferencing, too
> >
> > BugLink: http://bugzilla.opensuse.org/show_bug.cgi?id=1184074
> > Cc: <[email protected]>
> > Signed-off-by: Takashi Iwai <[email protected]>
> > ---
> > drivers/gpu/drm/i915/display/intel_acpi.c | 22 ++++++++++++++++++++--
> > 1 file changed, 20 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/display/intel_acpi.c b/drivers/gpu/drm/i915/display/intel_acpi.c
> > index e21fb14d5e07..833d0c1be4f1 100644
> > --- a/drivers/gpu/drm/i915/display/intel_acpi.c
> > +++ b/drivers/gpu/drm/i915/display/intel_acpi.c
> > @@ -84,13 +84,31 @@ static void intel_dsm_platform_mux_info(acpi_handle dhandle)
> > return;
> > }
> >
> > + if (!pkg->package.count) {
> > + DRM_DEBUG_DRIVER("no connection in _DSM\n");
> > + return;
> > + }
> > +
> > connector_count = &pkg->package.elements[0];
> > DRM_DEBUG_DRIVER("MUX info connectors: %lld\n",
> > (unsigned long long)connector_count->integer.value);
> > for (i = 1; i < pkg->package.count; i++) {
> > union acpi_object *obj = &pkg->package.elements[i];
> > - union acpi_object *connector_id = &obj->package.elements[0];
> > - union acpi_object *info = &obj->package.elements[1];
> > + union acpi_object *connector_id;
> > + union acpi_object *info;
> > +
> > + if (obj->type != ACPI_TYPE_PACKAGE || obj->package.count < 2) {
> > + DRM_DEBUG_DRIVER("Invalid object for MUX #%d\n", i);
> > + continue;
> > + }
> > +
> > + connector_id = &obj->package.elements[0];
>
> You don't want to check connector_id->type as well?

I added only the minimal checks that may lead to Oops.


Takashi

>
> > + info = &obj->package.elements[1];
> > + if (info->type != ACPI_TYPE_BUFFER || info->buffer.length < 4) {
> > + DRM_DEBUG_DRIVER("Invalid info for MUX obj #%d\n", i);
> > + continue;
> > + }
> > +
> > DRM_DEBUG_DRIVER("Connector id: 0x%016llx\n",
> > (unsigned long long)connector_id->integer.value);
> > DRM_DEBUG_DRIVER(" port id: %s\n",
> > --
> > 2.26.2
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > [email protected]
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>
> --
> Ville Syrjälä
> Intel
>