[PATCH] riscv: cacheinfo: Fix node reference leak in populate_cache_leaves

[PATCH] riscv: cacheinfo: Fix node reference leak in populate_cache_leaves

[Zishun Yi]

Currently, the while loop drops the reference to prev in each iteration.
If the loop terminates early due to a break, the final of_node_put(np)
correctly drops the reference to the current node.

However, if the loop terminates naturally because np == NULL, calling
of_node_put(np) is a no-op. This leaves the last valid node stored in
prev without its reference dropped, resulting in a node reference leak.

Fix this by changing the final `of_node_put(np)` to `of_node_put(prev)`.

Fixes: 94f9bf118f1e ("RISC-V: Fix of_node_* refcount")
Cc: stable@vger.kernel.org
Signed-off-by: Zishun Yi <vulab@iscas.ac.cn>
---
I saw 37233169a6ea ("riscv: Prevent a bad reference count on CPU nodes")
added the stable tag and fixed a similar issue, so I included it here as
well.

 arch/riscv/kernel/cacheinfo.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c
index 26b085dbdd07..6c9a1ef2d45a 100644
--- a/arch/riscv/kernel/cacheinfo.c
+++ b/arch/riscv/kernel/cacheinfo.c
@@ -133,7 +133,7 @@ int populate_cache_leaves(unsigned int cpu)
 			ci_leaf_init(this_leaf++, CACHE_TYPE_DATA, level);
 		levels = level;
 	}
-	of_node_put(np);
+	of_node_put(prev);
 
 	return 0;
 }
-- 
2.51.2

Re: [PATCH] riscv: cacheinfo: Fix node reference leak in populate_cache_leaves

[Markus Elfring]

…
> Fix this by changing the final `of_node_put(np)` to `of_node_put(prev)`.

How do you think about to use a wording approach like “Thus replace
the passed variable np by prev in an of_node_put() call at the end of
this function implementation”?


…
> Signed-off-by: Zishun Yi <vulab@iscas.ac.cn>

Can further clarifications become helpful also for the safe usage of
the Developer's Certificate of Origin?

Regards,
Markus