Re: arch/arm/mach-ep93xx/clock.c:154:2: warning: Use of memory after it is freed [clang-analyzer-unix.Malloc]
From: Nick Desaulniers
Date: Tue Jan 25 2022 - 16:08:18 EST
On Tue, Jan 25, 2022 at 12:01 AM Nikita Shubin
<nikita.shubin@xxxxxxxxxxx> wrote:
>
> Hello Nick,
>
> On Mon, 24 Jan 2022 13:50:02 -0800
> Nick Desaulniers <ndesaulniers@xxxxxxxxxx> wrote:
>
> > On Wed, Jan 19, 2022 at 5:46 PM kernel test robot
> > <yujie.liu@xxxxxxxxx> 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@xxxxxxxxx/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?
>
> Of course, i thought Alexander Sverdlin - already took care of it, he
> is really fast and fires patches before i even realize what happens.
>
> Alexander have you already taken care of it ? If not it's my turn to
> clear my own mess.
Alexander sent me privately the link to:
https://lore.kernel.org/lkml/20220120133739.4170298-2-alexander.sverdlin@xxxxxxxxx/T/
>
> >
> > >
> > > If you fix the issue, kindly add following tag as appropriate
> > > Reported-by: kernel test robot <lkp@xxxxxxxxx>
> > >
> > >
> > > 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@xxxxxxxxxxxx
> > >
> >
> >
>
--
Thanks,
~Nick Desaulniers