[Intel-gfx] [PATCH 9/9] drm/i915/dmc: protect against loading wrong firmware

[Srivatsa, Anusha]

>-----Original Message-----
>From: De Marchi, Lucas
>Sent: Friday, June 7, 2019 2:13 AM
>To: intel-gfx at lists.freedesktop.org
>Cc: Vivi, Rodrigo <rodrigo.vivi at intel.com>; Srivatsa, Anusha
><anusha.srivatsa at intel.com>; De Marchi, Lucas <lucas.demarchi at intel.com>
>Subject: [PATCH 9/9] 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 at intel.com>
>---
> drivers/gpu/drm/i915/intel_csr.c | 14 +++++++++++---
> 1 file changed, 11 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/gpu/drm/i915/intel_csr.c b/drivers/gpu/drm/i915/intel_csr.c
>index 7608e4e2950d..864531aae1a5 100644
>--- 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;

Wont we need a message here? "Wrong DMC version, not loading v_x.0x" or something?.." 

Anusha 
> 		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);
>--
>2.21.0