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

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Date:   Fri, 28 Jan 2022 11:19:12 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Zhou Qingyang <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: Re: [PATCH] clk: socfpga: Fix a memory leak bug in
 socfpga_gate_init()

On Tue, Jan 25, 2022 at 12:53:16AM +0800, Zhou Qingyang wrote:
> 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
> 

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