drm/mediatek: Add missing IS_ERR check for ovl_adaptor platform devicegrafted

platform_device_register_data() can fail and return an ERR_PTR, but the
return value is used without checking, leading to an invalid pointer
being stored in ddp_comp[].dev and passed to component_match_add() and
mtk_ddp_comp_init(), which could result in a kernel crash.

Add an IS_ERR() check to jump to the error handling path on failure.

Fixes: 0d9eee9118b7 ("drm/mediatek: Add drm ovl_adaptor sub driver for MT8195")
Cc: stable@vger.kernel.org
Signed-off-by: Haojie Li <lihaojie@kylinos.cn>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/linux-mediatek/patch/20260825100845.438893-1-lihaojie@kylinos.cn/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

1 files changed, 68 insertions, 0 deletions

diff --git a/tools/perf/util/demangle-ocaml.c b/tools/perf/util/demangle-ocaml.c
new file mode 100644
index 000000000..9d707bb60
--- /dev/null
+++ b/tools/perf/util/demangle-ocaml.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <string.h>
+#include <stdlib.h>
+#include "util/string2.h"
+
+#include "demangle-ocaml.h"
+
+#include <linux/ctype.h>
+
+static const char *caml_prefix = "caml";
+static const size_t caml_prefix_len = 4;
+
+/* mangled OCaml symbols start with "caml" followed by an upper-case letter */
+static bool
+ocaml_is_mangled(const char *sym)
+{
+	return 0 == strncmp(sym, caml_prefix, caml_prefix_len)
+		&& isupper(sym[caml_prefix_len]);
+}
+
+/*
+ * input:
+ *     sym: a symbol which may have been mangled by the OCaml compiler
+ * return:
+ *     if the input doesn't look like a mangled OCaml symbol, NULL is returned
+ *     otherwise, a newly allocated string containing the demangled symbol is returned
+ */
+char *
+ocaml_demangle_sym(const char *sym)
+{
+	char *result;
+	int j = 0;
+	int i;
+	int len;
+
+	if (!ocaml_is_mangled(sym)) {
+		return NULL;
+	}
+
+	len = strlen(sym);
+
+	/* the demangled symbol is always smaller than the mangled symbol */
+	result = malloc(len + 1);
+	if (!result)
+		return NULL;
+
+	/* skip "caml" prefix */
+	i = caml_prefix_len;
+
+	while (i < len) {
+		if (sym[i] == '_' && sym[i + 1] == '_') {
+			/* "__" -> "." */
+			result[j++] = '.';
+			i += 2;
+		}
+		else if (sym[i] == '$' && isxdigit(sym[i + 1]) && isxdigit(sym[i + 2])) {
+			/* "$xx" is a hex-encoded character */
+			result[j++] = (hex(sym[i + 1]) << 4) | hex(sym[i + 2]);
+			i += 3;
+		}
+		else {
+			result[j++] = sym[i++];
+		}
+	}
+	result[j] = '\0';
+
+	return result;
+}