riscv: hwprobe: avoid uninitialized variable use in hwprobe_arch_id()

Resolve this smatch warning:

arch/riscv/kernel/sys_hwprobe.c:50 hwprobe_arch_id() error: uninitialized symbol 'cpu_id'.

This could happen if hwprobe_arch_id() was called with a key ID of something other than MVENDORID, MIMPID, and MARCHID. This does not happen in the current codebase. The only caller of hwprobe_arch_id() is a function that only passes one of those three key IDs.

For the sake of reducing static analyzer warning noise, and in the unlikely event that hwprobe_arch_id() is someday called with some other key ID, validate hwprobe_arch_id()'s input to ensure that 'cpu_id' is always initialized before use.

---
 arch/riscv/kernel/sys_hwprobe.c | 6 ++++++
 1 file changed, 6 insertions(+)

index bc87bb9725fd..199d13f86f31 100644
@@ -31,6 +31,11 @@ static void hwprobe_arch_id(struct riscv_hwprobe *pair,
 	bool first = true;
 	int cpu;
 
+	if (pair->key != RISCV_HWPROBE_KEY_MVENDORID &&
+	    pair->key != RISCV_HWPROBE_KEY_MIMPID &&
+	    pair->key != RISCV_HWPROBE_KEY_MARCHID)
+		goto out;
+
 	for_each_cpu(cpu, cpus) {
 		u64 cpu_id;
 

@@ -61,6 +66,7 @@ static void hwprobe_arch_id(struct riscv_hwprobe *pair,
 		}
 	}
 
+out:
 	pair->value = id;
 }
 

2.48.1


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