From: Takashi Iwai Date: Fri, 2 Apr 2021 08:23:17 +0000 (+0200) Subject: drm/i915: Fix invalid access to ACPI _DSM objects X-Git-Tag: v5.15~303^2~29^2~241 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=337d7a1621c7f02af867229990ac67c97da1b53a;p=platform%2Fkernel%2Flinux-starfive.git 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: Signed-off-by: Takashi Iwai Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20210402082317.871-1-tiwai@suse.de --- diff --git a/drivers/gpu/drm/i915/display/intel_acpi.c b/drivers/gpu/drm/i915/display/intel_acpi.c index e21fb14..833d0c1 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",