linux-kernel - [PATCH] clk: socfpga: Fix a memory leak bug in socfpga_gate

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Date:   Tue, 25 Jan 2022 00:53:16 +0800
From:   Zhou Qingyang <zhou1615@....edu>
To:     zhou1615@....edu
Cc:     kjlu@....edu, Dinh Nguyen <dinguyen@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] clk: socfpga: Fix a memory leak bug in socfpga_gate_init()

In socfpga_gate_init(), when ops fails, socfpga_clk is not released or
passed out, which could lead to a memleak.

Fix this bug by adding a kfree of socfpga_clk on the failure path of ops.

This bug was found by a static analyzer.

Builds with 'make allyesconfig' show no new warnings,
and our static analyzer no longer warns about this code.

Fixes: a30a67be7b6e ("clk: socfpga: Don't have get_parent for single parent ops")
Signed-off-by: Zhou Qingyang <zhou1615@....edu>
---
The analysis employs differential checking to identify inconsistent 
security operations (e.g., checks or kfrees) between two code paths 
and confirms that the inconsistent operations are not recovered in the
current function or the callers, so they constitute bugs. 

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

 drivers/clk/socfpga/clk-gate.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/socfpga/clk-gate.c b/drivers/clk/socfpga/clk-gate.c
index 53d6e3ec4309..0ca5e0000925 100644
--- a/drivers/clk/socfpga/clk-gate.c
+++ b/drivers/clk/socfpga/clk-gate.c
@@ -188,8 +188,10 @@ void __init socfpga_gate_init(struct device_node *node)
 		return;
 
 	ops = kmemdup(&gateclk_ops, sizeof(gateclk_ops), GFP_KERNEL);
-	if (WARN_ON(!ops))
+	if (WARN_ON(!ops)) {
+		kfree(socfpga_clk);
 		return;
+	}
 
 	rc = of_property_read_u32_array(node, "clk-gate", clk_gate, 2);
 	if (rc)
-- 
2.25.1