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SubjectRe: [PATCH] x86: profiling: Set prof_cpu_mask to NULL after free
From
prof_cpu_mask can't be set to NULL when CONFIG_CPUMASK_OFFSTACK=n, 
because it is an array.

But checking prof_buffer still can prevent prof_cpu_mask be used in
profile_tick() and fix this problem.

Will push another version for this.


On 2023/2/25 6:16, kernel test robot wrote:
> Hi Chen,
>
> Thank you for the patch! Yet something to improve:
>
> [auto build test ERROR on linus/master]
> [also build test ERROR on v6.2 next-20230224]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use '--base' as documented in
> https://git-scm.com/docs/git-format-patch#_base_tree_information]
>
> url: https://github.com/intel-lab-lkp/linux/commits/Chen-Zhongjin/x86-profiling-Set-prof_cpu_mask-to-NULL-after-free/20230224-165419
> patch link: https://lore.kernel.org/r/20230224084945.134038-1-chenzhongjin%40huawei.com
> patch subject: [PATCH] x86: profiling: Set prof_cpu_mask to NULL after free
> config: arm-randconfig-r004-20230222 (https://download.01.org/0day-ci/archive/20230225/202302250609.vmze90DB-lkp@intel.com/config)
> compiler: clang version 17.0.0 (https://github.com/llvm/llvm-project db89896bbbd2251fff457699635acbbedeead27f)
> 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://github.com/intel-lab-lkp/linux/commit/ed9b4879e816862f4f6210b1c429bcbebac6d317
> git remote add linux-review https://github.com/intel-lab-lkp/linux
> git fetch --no-tags linux-review Chen-Zhongjin/x86-profiling-Set-prof_cpu_mask-to-NULL-after-free/20230224-165419
> git checkout ed9b4879e816862f4f6210b1c429bcbebac6d317
> # save the config file
> mkdir build_dir && cp config build_dir/.config
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm olddefconfig
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> | Reported-by: kernel test robot <lkp@intel.com>
> | Link: https://lore.kernel.org/oe-kbuild-all/202302250609.vmze90DB-lkp@intel.com/
>
> All errors (new ones prefixed by >>):
>
>>> kernel/profile.c:136:16: error: array type 'cpumask_var_t' (aka 'struct cpumask[1]') is not assignable
> prof_cpu_mask = NULL;
> ~~~~~~~~~~~~~ ^
> 1 error generated.
>
>
> vim +136 kernel/profile.c
>
> 98
> 99
> 100 int __ref profile_init(void)
> 101 {
> 102 int buffer_bytes;
> 103 if (!prof_on)
> 104 return 0;
> 105
> 106 /* only text is profiled */
> 107 prof_len = (_etext - _stext) >> prof_shift;
> 108
> 109 if (!prof_len) {
> 110 pr_warn("profiling shift: %u too large\n", prof_shift);
> 111 prof_on = 0;
> 112 return -EINVAL;
> 113 }
> 114
> 115 buffer_bytes = prof_len*sizeof(atomic_t);
> 116
> 117 if (!alloc_cpumask_var(&prof_cpu_mask, GFP_KERNEL))
> 118 return -ENOMEM;
> 119
> 120 cpumask_copy(prof_cpu_mask, cpu_possible_mask);
> 121
> 122 prof_buffer = kzalloc(buffer_bytes, GFP_KERNEL|__GFP_NOWARN);
> 123 if (prof_buffer)
> 124 return 0;
> 125
> 126 prof_buffer = alloc_pages_exact(buffer_bytes,
> 127 GFP_KERNEL|__GFP_ZERO|__GFP_NOWARN);
> 128 if (prof_buffer)
> 129 return 0;
> 130
> 131 prof_buffer = vzalloc(buffer_bytes);
> 132 if (prof_buffer)
> 133 return 0;
> 134
> 135 free_cpumask_var(prof_cpu_mask);
> > 136 prof_cpu_mask = NULL;
> 137 return -ENOMEM;
> 138 }
> 139
>

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