linux-kernel - [PATCH v2 2/2] mailbox: mtk-cmdq: Fix local clock ID usage

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Message-Id: <20211014120352.1506321-3-fshao@chromium.org>
Date:   Thu, 14 Oct 2021 20:03:52 +0800
From:   Fei Shao <fshao@...omium.org>
To:     Jassi Brar <jaswinder.singh@...aro.org>
Cc:     Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Tzung-Bi Shih <tzungbi@...gle.com>,
        Fei Shao <fshao@...omium.org>,
        Jassi Brar <jassisinghbrar@...il.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        "jason-jh.lin" <jason-jh.lin@...iatek.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-mediatek@...ts.infradead.org
Subject: [PATCH v2 2/2] mailbox: mtk-cmdq: Fix local clock ID usage

In the probe function, the clock IDs were pointed to local variables
which should only be used in the same code block, and any access to them
after the probing stage becomes an use-after-free case.

Since there are only limited variants of the gce clock names so far, we
can just declare them as static constants to fix the issue.

Fixes: 85dfdbfc13ea ("mailbox: cmdq: add multi-gce clocks support for
mt8195")
Signed-off-by: Fei Shao <fshao@...omium.org>
---

Changes in v2:
- Make clock names static

 drivers/mailbox/mtk-cmdq-mailbox.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/mailbox/mtk-cmdq-mailbox.c b/drivers/mailbox/mtk-cmdq-mailbox.c
index f3e52dddd422..95ce7275641c 100644
--- a/drivers/mailbox/mtk-cmdq-mailbox.c
+++ b/drivers/mailbox/mtk-cmdq-mailbox.c
@@ -532,7 +532,8 @@ static int cmdq_probe(struct platform_device *pdev)
 	struct device_node *phandle = dev->of_node;
 	struct device_node *node;
 	int alias_id = 0;
-	char clk_name[4] = "gce";
+	static const char * const clk_name = "gce";
+	static const char * const clk_names[] = { "gce0", "gce1" };

 	cmdq = devm_kzalloc(dev, sizeof(*cmdq), GFP_KERNEL);
 	if (!cmdq)
@@ -570,12 +571,9 @@ static int cmdq_probe(struct platform_device *pdev)

 	if (cmdq->gce_num > 1) {
 		for_each_child_of_node(phandle->parent, node) {
-			char clk_id[8];
-
 			alias_id = of_alias_get_id(node, clk_name);
 			if (alias_id >= 0 && alias_id < cmdq->gce_num) {
-				snprintf(clk_id, sizeof(clk_id), "%s%d", clk_name, alias_id);
-				cmdq->clocks[alias_id].id = clk_id;
+				cmdq->clocks[alias_id].id = clk_names[alias_id];
 				cmdq->clocks[alias_id].clk = of_clk_get(node, 0);
 				if (IS_ERR(cmdq->clocks[alias_id].clk)) {
 					dev_err(dev, "failed to get gce clk: %d\n", alias_id);
--
2.33.0.882.g93a45727a2-goog