[PATCH 2/2] drm/i915/gsc: Validate the CPD entry offset before manifest read

[Jesus Narvaez <jesus.narvaez@intel.com>]

The CPD manifest offset was dereferenced without checking the bounds
first. Therefore, ensure the offset doesn't point into the CPD header
or past the bounds of the FW blob before reading the GSC manifest.

Also, validate CPD header length before using it to size the CPD
entry table, and cast the boot1 partition's offset and size to size_t
to avoid an integer overflow.

Discovered using AI-assisted static analysis confirmed by Intel Product
Security.

Reported-by: Martin Hodo <martin.hodo@intel.com>
Fixes: 56fafa569764 ("drm/i915/mtl/gsc: extract release and security versions from the gsc binary")
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Alan Previn <alan.previn.teres.alexis@intel.com>
Cc: <stable@vger.kernel.org> # v6.6+
Signed-off-by: Jesus Narvaez <jesus.narvaez@intel.com>
---
 drivers/gpu/drm/i915/gt/uc/intel_gsc_fw.c | 27 ++++++++++++++++++++---
 1 file changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_gsc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_gsc_fw.c
index d550eb6edfb8..1b9976869c46 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_gsc_fw.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_gsc_fw.c
@@ -139,7 +139,7 @@ int intel_gsc_fw_get_binary_info(struct intel_uc_fw *gsc_fw, const void *data, s
 	 * --------------------------------------------------
 	 */
 
-	min_size = layout->boot1.offset + layout->boot1.size;
+	min_size = (size_t)layout->boot1.offset + layout->boot1.size;
 	if (size < min_size) {
 		gt_err(gt, "GSC FW too small for boot section! %zu < %zu\n",
 		       size, min_size);
@@ -195,7 +195,14 @@ int intel_gsc_fw_get_binary_info(struct intel_uc_fw *gsc_fw, const void *data, s
 		return -EINVAL;
 	}
 
-	min_size += sizeof(*cpd_entry) * cpd_header->num_of_entries;
+	if (cpd_header->header_length < sizeof(struct intel_gsc_cpd_header_v2)) {
+		gt_err(gt, "invalid CPD header length in GSC bin: %u < %zu!\n",
+		       cpd_header->header_length, sizeof(*cpd_header));
+		return -EINVAL;
+	}
+
+	min_size = bpdt_entry->sub_partition_offset + cpd_header->header_length +
+		   sizeof(*cpd_entry) * cpd_header->num_of_entries;
 	if (layout->boot1.size < min_size) {
 		gt_err(gt, "GSC FW boot section too small for CPD entries: %u < %zu\n",
 		       layout->boot1.size, min_size);
@@ -205,7 +212,21 @@ int intel_gsc_fw_get_binary_info(struct intel_uc_fw *gsc_fw, const void *data, s
 	cpd_entry = (void *)cpd_header + cpd_header->header_length;
 	for (i = 0; i < cpd_header->num_of_entries; i++, cpd_entry++) {
 		if (strcmp(cpd_entry->name, "RBEP.man") == 0) {
-			manifest = (void *)cpd_header + cpd_entry_offset(cpd_entry);
+			u32 man_off = cpd_entry_offset(cpd_entry);
+
+			if (man_off < cpd_header->header_length) {
+				gt_err(gt, "GSC FW manifest offset points into CPD header: %u < %u\n",
+				       man_off, cpd_header->header_length);
+				return -EINVAL;
+			}
+
+			if (man_off + sizeof(struct intel_gsc_manifest_header) >
+			    layout->boot1.size - bpdt_entry->sub_partition_offset) {
+				gt_err(gt, "GSC FW boot section too small for manifest: %u < %zu\n",
+				       layout->boot1.size, man_off + sizeof(*manifest));
+				return -ENODATA;
+			}
+			manifest = (void *)cpd_header + man_off;
 			intel_uc_fw_version_from_gsc_manifest(&gsc->release,
 							      manifest);
 			gsc->security_version = manifest->security_version;
-- 
2.43.0