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drm/i915: Fix invalid access to ACPI _DSM objects

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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: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210402082317.871-1-tiwai@suse.de
This commit is contained in:
Takashi Iwai 2021-04-02 10:23:17 +02:00 committed by Ville Syrjälä
parent 11cda4967a
commit 337d7a1621
1 changed files with 20 additions and 2 deletions
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22
drivers/gpu/drm/i915/display/intel_acpi.c
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@ -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",