drm/i915/dmc: protect against loading wrong firmware

In intel_package_header version 2 there's a new field in the
fw_info table that must be 0, otherwise it's not the correct DMC
firmware. Add a check for version 2 or later.

Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
Reviewed-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190607091230.1489-10-lucas.demarchi@intel.com

diff --git a/drivers/gpu/drm/i915/intel_csr.c b/drivers/gpu/drm/i915/intel_csr.c
index 0316715..6ef7453 100644 (file)
--- a/drivers/gpu/drm/i915/intel_csr.c
+++ b/drivers/gpu/drm/i915/intel_csr.c
@@ -120,7 +120,10 @@ struct intel_css_header {
 } __packed;
 
 struct intel_fw_info {
-       u16 reserved1;
+       u8 reserved1;
+
+       /* reserved on package_header version 1, must be 0 on version 2 */
+       u8 dmc_id;
 
        /* Stepping (A, B, C, ..., *). * is a wildcard */
        char stepping;
@@ -325,12 +328,16 @@ void intel_csr_load_program(struct drm_i915_private *dev_priv)
  */
 static u32 find_dmc_fw_offset(const struct intel_fw_info *fw_info,
                              unsigned int num_entries,
-                             const struct stepping_info *si)
+                             const struct stepping_info *si,
+                             u8 package_ver)
 {
        u32 dmc_offset = CSR_DEFAULT_FW_OFFSET;
        unsigned int i;
 
        for (i = 0; i < num_entries; i++) {
+               if (package_ver > 1 && fw_info[i].dmc_id != 0)
+                       continue;
+
                if (fw_info[i].substepping == '*' &&
                    si->stepping == fw_info[i].stepping) {
                        dmc_offset = fw_info[i].offset;
@@ -508,7 +515,8 @@ parse_csr_fw_package(struct intel_csr *csr,
 
        fw_info = (const struct intel_fw_info *)
                ((u8 *)package_header + sizeof(*package_header));
-       dmc_offset = find_dmc_fw_offset(fw_info, num_entries, si);
+       dmc_offset = find_dmc_fw_offset(fw_info, num_entries, si,
+                                       package_header->header_ver);
        if (dmc_offset == CSR_DEFAULT_FW_OFFSET) {
                DRM_ERROR("DMC firmware not supported for %c stepping\n",
                          si->stepping);