[Intel-gfx] [PATCH 8/8] drm/i915/guc: Fix potential invalid pointer dereferences when decoding G2Hs

[John . C . Harrison]

From: John Harrison <john.c.harri...@intel.com>

Some G2H handlers were reading the context id field from the payload
before checking the payload met the minimum length required.

Signed-off-by: John Harrison <john.c.harri...@intel.com>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c 
b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
index b70b1ff46418..ea17dca68674 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_submission.c
@@ -3895,12 +3895,13 @@ int intel_guc_deregister_done_process_msg(struct 
intel_guc *guc,
                                          u32 len)
 {
        struct intel_context *ce;
-       u32 ctx_id = msg[0];
+       u32 ctx_id;
 
        if (unlikely(len < 1)) {
                drm_err(&guc_to_gt(guc)->i915->drm, "Invalid length %u\n", len);
                return -EPROTO;
        }
+       ctx_id = msg[0];
 
        ce = g2h_context_lookup(guc, ctx_id);
        if (unlikely(!ce))
@@ -3946,12 +3947,13 @@ int intel_guc_sched_done_process_msg(struct intel_guc 
*guc,
 {
        struct intel_context *ce;
        unsigned long flags;
-       u32 ctx_id = msg[0];
+       u32 ctx_id;
 
        if (unlikely(len < 2)) {
                drm_err(&guc_to_gt(guc)->i915->drm, "Invalid length %u\n", len);
                return -EPROTO;
        }
+       ctx_id = msg[0];
 
        ce = g2h_context_lookup(guc, ctx_id);
        if (unlikely(!ce))
-- 
2.25.1