fix(tools): eliminate UBSan -fsanitize=function violations in vidinput vtbl

changelog.d/fixed/ubsan-vidinput-vtbl-function-ptr-mismatch.md

@@ -0,0 +1,7 @@
+Fix UBSan `-fsanitize=function` violations in `vidinput.c` vtbl dispatch:
+`yuv_input.c` and `y4m_input.c` functions registered in `YUV_INPUT_VTBL` /
+`Y4M_INPUT_VTBL` used concrete `yuv_input *` / `y4m_input *` parameter types
+instead of the erased `void *` mandated by the typedef in `vidinput.h`.
+UBSan detected these as type-mismatched indirect calls on every frame read.
+Added vtbl-compatible static wrapper functions; removed C-style casts from
+both VTBL initialisers. Netflix golden scores unchanged.

core/tools/y4m_input.c

@@ -1016,12 +1016,42 @@ static int y4m_fetch_into_vmaf_picture(y4m_input *_y4m, FILE *_fin, VmafPicture
     return 1;
 }
 
-OC_EXTERN const video_input_vtbl Y4M_INPUT_VTBL = {
-    (raw_input_open_func)NULL,
-    (video_input_open_func)y4m_input_open,
-    (video_input_get_info_func)y4m_input_get_info,
-    (video_input_fetch_frame_func)y4m_input_fetch_frame,
-    (video_input_close_func)y4m_input_close,
-    (video_input_fetch_into_vmaf_picture_func)y4m_fetch_into_vmaf_picture};
+/*
+ * vtbl-compatible wrapper functions — match the exact function pointer
+ * signatures in vidinput.h to avoid UBSan -fsanitize=function violations.
+ * The concrete y4m_input* implementations remain typed for readability.
+ */
+static void *y4m_vtbl_open(FILE *fin)
+{
+    return y4m_input_open(fin);
+}
+
+static void y4m_vtbl_get_info(void *ctx, video_input_info *info)
+{
+    y4m_input_get_info((y4m_input *)ctx, info);
+}
+
+static int y4m_vtbl_fetch_frame(void *ctx, FILE *fin, video_input_ycbcr ycbcr, char tag[5])
+{
+    return y4m_input_fetch_frame((y4m_input *)ctx, fin, ycbcr, tag);
+}
+
+static void y4m_vtbl_close(void *ctx)
+{
+    y4m_input_close((y4m_input *)ctx);
+}
+
+static int y4m_vtbl_fetch_into_vmaf_picture(void *ctx, FILE *fin, VmafPicture *pic)
+{
+    return y4m_fetch_into_vmaf_picture((y4m_input *)ctx, fin, pic);
+}
+
+// NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables) — extern linkage required: vidinput.c references this symbol via `extern video_input_vtbl Y4M_INPUT_VTBL`
+OC_EXTERN const video_input_vtbl Y4M_INPUT_VTBL = {NULL,
+                                                   y4m_vtbl_open,
+                                                   y4m_vtbl_get_info,
+                                                   y4m_vtbl_fetch_frame,
+                                                   y4m_vtbl_close,
+                                                   y4m_vtbl_fetch_into_vmaf_picture};
 
 // NOLINTEND(bugprone-unchecked-string-to-number-conversion,cert-err34-c)

core/tools/yuv_input.c

@@ -303,11 +303,40 @@ static int yuv_fetch_into_vmaf_picture(yuv_input *yuv, FILE *fin, VmafPicture *p
     return 1;
 }
 
+/*
+ * vtbl-compatible wrapper functions — each matches the exact function pointer
+ * signature in vidinput.h so the VTBL initializer below requires no C-style
+ * casts.  The casts were previously silencing a type mismatch between the
+ * concrete `yuv_input *` parameter and the erased `void *` in the typedef,
+ * which UBSan's -fsanitize=function detects at runtime as undefined behaviour.
+ * The concrete implementations remain typed for readability and safety.
+ */
+static void *yuv_vtbl_open_raw(FILE *fin, unsigned w, unsigned h, int pix_fmt, unsigned bitdepth)
+{
+    return yuv_input_open(fin, w, h, (enum VmafPixelFormat)pix_fmt, bitdepth);
+}
+
+static void yuv_vtbl_get_info(void *ctx, video_input_info *info)
+{
+    yuv_input_get_info((yuv_input *)ctx, info);
+}
+
+static int yuv_vtbl_fetch_frame(void *ctx, FILE *fin, video_input_ycbcr ycbcr, char tag[5])
+{
+    return yuv_input_fetch_frame((yuv_input *)ctx, fin, ycbcr, tag);
+}
+
+static void yuv_vtbl_close(void *ctx)
+{
+    yuv_input_close((yuv_input *)ctx);
+}
+
+static int yuv_vtbl_fetch_into_vmaf_picture(void *ctx, FILE *fin, VmafPicture *pic)
+{
+    return yuv_fetch_into_vmaf_picture((yuv_input *)ctx, fin, pic);
+}
+
 // NOLINTNEXTLINE(cppcoreguidelines-avoid-non-const-global-variables) — extern linkage required: vidinput.c references this symbol via `extern video_input_vtbl YUV_INPUT_VTBL`
 OC_EXTERN const video_input_vtbl YUV_INPUT_VTBL = {
-    (raw_input_open_func)yuv_input_open,
-    (video_input_open_func)NULL,
-    (video_input_get_info_func)yuv_input_get_info,
-    (video_input_fetch_frame_func)yuv_input_fetch_frame,
-    (video_input_close_func)yuv_input_close,
-    (video_input_fetch_into_vmaf_picture_func)yuv_fetch_into_vmaf_picture};
+    yuv_vtbl_open_raw,    NULL,           yuv_vtbl_get_info,
+    yuv_vtbl_fetch_frame, yuv_vtbl_close, yuv_vtbl_fetch_into_vmaf_picture};