linux-kernel - arch/arm/mach-ep93xx/clock.c:154:2: warning: Use of memory after it is freed [clang-analyzer-unix.Malloc]

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Date:   Thu, 20 Jan 2022 09:46:36 +0800
From:   kernel test robot <yujie.liu@...el.com>
To:     Nikita Shubin <nikita.shubin@...uefel.me>
CC:     <llvm@...ts.linux.dev>, <kbuild-all@...ts.01.org>,
        "Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Alexander Sverdlin" <alexander.sverdlin@...il.com>
Subject: arch/arm/mach-ep93xx/clock.c:154:2: warning: Use of memory after it
 is freed [clang-analyzer-unix.Malloc]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   1d1df41c5a33359a00e919d54eaebfb789711fdc
commit: 9645ccc7bd7a16cd73c3be9dee70cd702b03be37 ep93xx: clock: convert in-place to COMMON_CLK
date:   3 months ago
config: arm-randconfig-c002-20220118 (https://download.01.org/0day-ci/archive/20220120/202201200359.lTk9zHg4-lkp@intel.com/config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 5f782d25a742302d25ef3c8b84b54f7483c2deb9)
reproduce (this is a W=1 build):
         wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
         chmod +x ~/bin/make.cross
         # install arm cross compiling tool for clang build
         # apt-get install binutils-arm-linux-gnueabi
         # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9645ccc7bd7a16cd73c3be9dee70cd702b03be37
         git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
         git fetch --no-tags linus master
         git checkout 9645ccc7bd7a16cd73c3be9dee70cd702b03be37
         # save the config file to linux build tree
         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=arm clang-analyzer

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@...el.com>


clang-analyzer warnings: (new ones prefixed by >>)

 >> arch/arm/mach-ep93xx/clock.c:154:2: warning: Use of memory after it is freed [clang-analyzer-unix.Malloc]
            return &psc->hw;
            ^
    arch/arm/mach-ep93xx/clock.c:151:2: note: Taking true branch
            if (IS_ERR(clk))
            ^
    arch/arm/mach-ep93xx/clock.c:152:3: note: Memory is released
                    kfree(psc);
                    ^~~~~~~~~~
    arch/arm/mach-ep93xx/clock.c:154:2: note: Use of memory after it is freed
            return &psc->hw;
            ^      ~~~~~~~~
 >> arch/arm/mach-ep93xx/clock.c:484:2: warning: Value stored to 'hw' is never read [clang-analyzer-deadcode.DeadStores]
            hw = clk_hw_register_fixed_factor(NULL, "uart", "xtali", 0, 1, clk_uart_div);
            ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 >> arch/arm/mach-ep93xx/clock.c:612:2: warning: Value stored to 'hw' is never read [clang-analyzer-deadcode.DeadStores]
            hw = clk_hw_register_fixed_factor(NULL, "usb_clk", "pll2", 0, 1, clk_usb_div);
            ^    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

vim +154 arch/arm/mach-ep93xx/clock.c

ff05c0330b9880 Hartley Sweeten 2009-05-07  125
9645ccc7bd7a16 Nikita Shubin   2021-10-18  126  static struct clk_hw *ep93xx_clk_register_gate(const char *name,
9645ccc7bd7a16 Nikita Shubin   2021-10-18  127  				    const char *parent_name,
9645ccc7bd7a16 Nikita Shubin   2021-10-18  128  				    void __iomem *reg,
9645ccc7bd7a16 Nikita Shubin   2021-10-18  129  				    u8 bit_idx)
9645ccc7bd7a16 Nikita Shubin   2021-10-18  130  {
9645ccc7bd7a16 Nikita Shubin   2021-10-18  131  	struct clk_init_data init;
9645ccc7bd7a16 Nikita Shubin   2021-10-18  132  	struct clk_psc *psc;
9645ccc7bd7a16 Nikita Shubin   2021-10-18  133  	struct clk *clk;
9645ccc7bd7a16 Nikita Shubin   2021-10-18  134
9645ccc7bd7a16 Nikita Shubin   2021-10-18  135  	psc = kzalloc(sizeof(*psc), GFP_KERNEL);
9645ccc7bd7a16 Nikita Shubin   2021-10-18  136  	if (!psc)
9645ccc7bd7a16 Nikita Shubin   2021-10-18  137  		return ERR_PTR(-ENOMEM);
9645ccc7bd7a16 Nikita Shubin   2021-10-18  138
9645ccc7bd7a16 Nikita Shubin   2021-10-18  139  	init.name = name;
9645ccc7bd7a16 Nikita Shubin   2021-10-18  140  	init.ops = &clk_ep93xx_gate_ops;
9645ccc7bd7a16 Nikita Shubin   2021-10-18  141  	init.flags = CLK_SET_RATE_PARENT;
9645ccc7bd7a16 Nikita Shubin   2021-10-18  142  	init.parent_names = (parent_name ? &parent_name : NULL);
9645ccc7bd7a16 Nikita Shubin   2021-10-18  143  	init.num_parents = (parent_name ? 1 : 0);
9645ccc7bd7a16 Nikita Shubin   2021-10-18  144
9645ccc7bd7a16 Nikita Shubin   2021-10-18  145  	psc->reg = reg;
9645ccc7bd7a16 Nikita Shubin   2021-10-18  146  	psc->bit_idx = bit_idx;
9645ccc7bd7a16 Nikita Shubin   2021-10-18  147  	psc->hw.init = &init;
9645ccc7bd7a16 Nikita Shubin   2021-10-18  148  	psc->lock = &clk_lock;
9645ccc7bd7a16 Nikita Shubin   2021-10-18  149
9645ccc7bd7a16 Nikita Shubin   2021-10-18  150  	clk = clk_register(NULL, &psc->hw);
9645ccc7bd7a16 Nikita Shubin   2021-10-18  151  	if (IS_ERR(clk))
9645ccc7bd7a16 Nikita Shubin   2021-10-18  152  		kfree(psc);
9645ccc7bd7a16 Nikita Shubin   2021-10-18  153
9645ccc7bd7a16 Nikita Shubin   2021-10-18 @154  	return &psc->hw;
ff05c0330b9880 Hartley Sweeten 2009-05-07  155  }
ff05c0330b9880 Hartley Sweeten 2009-05-07  156

---
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