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Date: Mon, 24 Jan 2022 13:50:02 -0800
From: Nick Desaulniers <ndesaulniers@...gle.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>,
kernel test robot <yujie.liu@...el.com>,
Nathan Huckleberry <nhuck@...gle.com>,
Philip Li <philip.li@...el.com>
Subject: Re: arch/arm/mach-ep93xx/clock.c:154:2: warning: Use of memory after
it is freed [clang-analyzer-unix.Malloc]
On Wed, Jan 19, 2022 at 5:46 PM kernel test robot <yujie.liu@...el.com> wrote:
>
> 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
Hey! This check finally caught something that looks legit! Cool to see
0day bot running clang-analyzer, too!
Nikita, can you PTAL?
>
> 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);
probably should `return ERR_CAST(clk);` ?
> 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
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
>
--
Thanks,
~Nick Desaulniers
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