[PATCH 1/3] Revert "drm/i915/gvt: Fix out-of-bounds buffer write into opregion->signature[]"

[Nicolas Chauvet <kwizart@gmail.com>]

This reverts commit ea26c96d59b27e878fe61e8ef0fed840d2281a2f.

This fix truncates the OPREGION_SIGNATURE to fit into 16 chars instead of
enlarging the target field, hence only moving the size missmatch to later.

As shown with gcc-15:
drivers/gpu/drm/i915/gvt/opregion.c: In function intel_vgpu_init_opregion:
drivers/gpu/drm/i915/gvt/opregion.c:35:28: error: initializer-string for array of char is too long [-Werror=unterminated-string-initialization]
   35 | #define OPREGION_SIGNATURE "IntelGraphicsMem"
      |                            ^~~~~~~~~~~~~~~~~~
drivers/gpu/drm/i915/gvt/opregion.c:225:45: note: in expansion of macro OPREGION_SIGNATURE
  225 |         const char opregion_signature[16] = OPREGION_SIGNATURE;
      |                                             ^~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Cc: stable@vger.kernel.org
Reported-by: Nicolas Chauvet <kwizart@gmail.com>
Fixes: ea26c96d59 ("drm/i915/gvt: Fix out-of-bounds buffer write into opregion->signature[]")
Signed-off-by: Nicolas Chauvet <kwizart@gmail.com>
---
 drivers/gpu/drm/i915/gvt/opregion.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/gvt/opregion.c b/drivers/gpu/drm/i915/gvt/opregion.c
index 509f9ccae3a9..9a8ead6039e2 100644
--- a/drivers/gpu/drm/i915/gvt/opregion.c
+++ b/drivers/gpu/drm/i915/gvt/opregion.c
@@ -222,7 +222,6 @@ int intel_vgpu_init_opregion(struct intel_vgpu *vgpu)
 	u8 *buf;
 	struct opregion_header *header;
 	struct vbt v;
-	const char opregion_signature[16] = OPREGION_SIGNATURE;
 
 	gvt_dbg_core("init vgpu%d opregion\n", vgpu->id);
 	vgpu_opregion(vgpu)->va = (void *)__get_free_pages(GFP_KERNEL |
@@ -236,8 +235,8 @@ int intel_vgpu_init_opregion(struct intel_vgpu *vgpu)
 	/* emulated opregion with VBT mailbox only */
 	buf = (u8 *)vgpu_opregion(vgpu)->va;
 	header = (struct opregion_header *)buf;
-	memcpy(header->signature, opregion_signature,
-	       sizeof(opregion_signature));
+	memcpy(header->signature, OPREGION_SIGNATURE,
+			sizeof(OPREGION_SIGNATURE));
 	header->size = 0x8;
 	header->opregion_ver = 0x02000000;
 	header->mboxes = MBOX_VBT;
-- 
2.49.0