tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   53e99dcff61e1523ec1c3628b2d564ba15d32eb7
commit: 0df8bdd5e3b3e557ce2c2575fce0c64c5dd1045a stackleak: move stack_erasing sysctl to stackleak.c
date:   8 months ago
config: x86_64-randconfig-s023-20220905
compiler: gcc-11 (Debian 11.3.0-5) 11.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-39-gce1a6720-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0df8bdd5e3b3e557ce2c2575fce0c64c5dd1045a
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 0df8bdd5e3b3e557ce2c2575fce0c64c5dd1045a
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=x86_64 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>

sparse warnings: (new ones prefixed by >>)
>> kernel/stackleak.c:33:50: sparse: sparse: incorrect type in argument 3 (different address spaces) @@     expected void * @@     got void [noderef] __user *buffer @@
   kernel/stackleak.c:33:50: sparse:     expected void *
   kernel/stackleak.c:33:50: sparse:     got void [noderef] __user *buffer
>> kernel/stackleak.c:53:35: sparse: sparse: incorrect type in initializer (incompatible argument 3 (different address spaces)) @@     expected int ( [usertype] *proc_handler )( ... ) @@     got int ( * )( ... ) @@
   kernel/stackleak.c:53:35: sparse:     expected int ( [usertype] *proc_handler )( ... )
   kernel/stackleak.c:53:35: sparse:     got int ( * )( ... )

vim +33 kernel/stackleak.c

964c9dff009189 Alexander Popov 2018-08-17  22  
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  23  #ifdef CONFIG_SYSCTL
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  24  static int stack_erasing_sysctl(struct ctl_table *table, int write,
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  25  			void __user *buffer, size_t *lenp, loff_t *ppos)
964c9dff009189 Alexander Popov 2018-08-17  26  {
964c9dff009189 Alexander Popov 2018-08-17  27  	int ret = 0;
964c9dff009189 Alexander Popov 2018-08-17  28  	int state = !static_branch_unlikely(&stack_erasing_bypass);
964c9dff009189 Alexander Popov 2018-08-17  29  	int prev_state = state;
964c9dff009189 Alexander Popov 2018-08-17  30  
964c9dff009189 Alexander Popov 2018-08-17  31  	table->data = &state;
964c9dff009189 Alexander Popov 2018-08-17  32  	table->maxlen = sizeof(int);
964c9dff009189 Alexander Popov 2018-08-17 @33  	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
964c9dff009189 Alexander Popov 2018-08-17  34  	state = !!state;
964c9dff009189 Alexander Popov 2018-08-17  35  	if (ret || !write || state == prev_state)
964c9dff009189 Alexander Popov 2018-08-17  36  		return ret;
964c9dff009189 Alexander Popov 2018-08-17  37  
964c9dff009189 Alexander Popov 2018-08-17  38  	if (state)
964c9dff009189 Alexander Popov 2018-08-17  39  		static_branch_disable(&stack_erasing_bypass);
964c9dff009189 Alexander Popov 2018-08-17  40  	else
964c9dff009189 Alexander Popov 2018-08-17  41  		static_branch_enable(&stack_erasing_bypass);
964c9dff009189 Alexander Popov 2018-08-17  42  
964c9dff009189 Alexander Popov 2018-08-17  43  	pr_warn("stackleak: kernel stack erasing is %s\n",
964c9dff009189 Alexander Popov 2018-08-17  44  					state ? "enabled" : "disabled");
964c9dff009189 Alexander Popov 2018-08-17  45  	return ret;
964c9dff009189 Alexander Popov 2018-08-17  46  }
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  47  static struct ctl_table stackleak_sysctls[] = {
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  48  	{
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  49  		.procname	= "stack_erasing",
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  50  		.data		= NULL,
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  51  		.maxlen		= sizeof(int),
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  52  		.mode		= 0600,
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21 @53  		.proc_handler	= stack_erasing_sysctl,
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  54  		.extra1		= SYSCTL_ZERO,
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  55  		.extra2		= SYSCTL_ONE,
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  56  	},
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  57  	{}
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  58  };
0df8bdd5e3b3e5 Xiaoming Ni     2022-01-21  59  

:::::: The code at line 33 was first introduced by commit
:::::: 964c9dff0091893a9a74a88edf984c6da0b779f7 stackleak: Allow runtime disabling of kernel stack erasing

:::::: TO: Alexander Popov <alex.popov@linux.com>
:::::: CC: Kees Cook <keescook@chromium.org>

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