tracing/probes: Add const to new_argv allocation type

From: Kees Cook <[email protected]>

In preparation for converting the kmalloc family of allocators to the type-aware kmalloc_obj family, we need to make sure that the returned type from the allocation matches the type of the variable being assigned. (The kmalloc family returns "void *", which can be implicitly cast to any pointer type.)

The assigned type is "const char **", but the converted allocation type would be "char **", which is the same type without the const qualifier. As there is no general way to safely add const qualifiers, take the size from the assignment target instead. No change in allocation size results.

Build tested ARCH=x86_64 allmodconfig with GCC 16.2.0:
kernel/trace/trace_probe.o

Assisted-by LLM coccinelle

Signed-off-by Kees Cook <[email protected]>

---
Cc: Steven Rostedt <[email protected]>
Cc: Masami Hiramatsu <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: <[email protected]>

---
 kernel/trace/trace_probe.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

kernel/trace/trace_probe.c +1 -1

index 804442b2f7d2..cfb710095f65 100644
@@ -2316,7 +2316,7 @@ const char **traceprobe_expand_meta_args(int argc, const char *argv[],
 	else
 		*new_argc = argc;
 
-	new_argv = kcalloc(*new_argc, sizeof(char *), GFP_KERNEL);
+	new_argv = kcalloc(*new_argc, sizeof(*new_argv), GFP_KERNEL);
 	if (!new_argv)
 		return ERR_PTR(-ENOMEM);
 

Signature · 1 line

2.34.1