Re: [PATCH] lkdtm/usercopy: Expand size of "out of frame" object

kernel test robot
2022-02-16T22:57:56Z

Hi Kees,

I love your patch! Yet something to improve:

[auto build test ERROR on char-misc/char-misc-testing]
[also build test ERROR on soc/for-next kees/for-next/pstore v5.17-rc4 next-20220216]
[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]

url: https://github.com/0day-ci/linux/commits/Kees-Cook/lkdtm-usercopy-Expand-size-of-out-of-frame-object/20220217-041936
base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git e6cb9c167eeb8f90ab924666c573e69e85e700a0
config: hexagon-randconfig-r045-20220216 (https://download.01.org/0day-ci/archive/20220217/202202170613.eIFMv4np-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project 0e628a783b935c70c80815db6c061ec84f884af5)
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
# https://github.com/0day-ci/linux/commit/aa676e88f535bd79a3e22a1cc70c9b6cc51dbbfe
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Kees-Cook/lkdtm-usercopy-Expand-size-of-out-of-frame-object/20220217-041936
git checkout aa676e88f535bd79a3e22a1cc70c9b6cc51dbbfe
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash drivers/misc/lkdtm/

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

All errors (new ones prefixed by >>):

>> drivers/misc/lkdtm/usercopy.c:74:39: error: use of undeclared identifier 'current_stack_pointer'
pr_info("stack : %px\n", (void *)current_stack_pointer);
^
1 error generated.

vim +/current_stack_pointer +74 drivers/misc/lkdtm/usercopy.c

53
54 static noinline void do_usercopy_stack(bool to_user, bool bad_frame)
55 {
56 unsigned long user_addr;
57 unsigned char good_stack[32];
58 unsigned char *bad_stack;
59 int i;
60
61 /* Exercise stack to avoid everything living in registers. */
62 for (i = 0; i < sizeof(good_stack); i++)
63 good_stack[i] = test_text[i % sizeof(test_text)];
64
65 /* This is a pointer to outside our current stack frame. */
66 if (bad_frame) {
67 bad_stack = do_usercopy_stack_callee((uintptr_t)&bad_stack);
68 } else {
69 /* Put start address just inside stack. */
70 bad_stack = task_stack_page(current) + THREAD_SIZE;
71 bad_stack -= sizeof(unsigned long);
72 }
73
> 74 pr_info("stack : %px\n", (void *)current_stack_pointer);
75 pr_info("good_stack: %px-%px\n", good_stack, good_stack + sizeof(good_stack));
76 pr_info("bad_stack : %px-%px\n", bad_stack, bad_stack + sizeof(good_stack));
77
78 user_addr = vm_mmap(NULL, 0, PAGE_SIZE,
79 PROT_READ | PROT_WRITE | PROT_EXEC,
80 MAP_ANONYMOUS | MAP_PRIVATE, 0);
81 if (user_addr >= TASK_SIZE) {
82 pr_warn("Failed to allocate user memory\n");
83 return;
84 }
85
86 if (to_user) {
87 pr_info("attempting good copy_to_user of local stack\n");
88 if (copy_to_user((void __user *)user_addr, good_stack,
89 unconst + sizeof(good_stack))) {
90 pr_warn("copy_to_user failed unexpectedly?!\n");
91 goto free_user;
92 }
93
94 pr_info("attempting bad copy_to_user of distant stack\n");
95 if (copy_to_user((void __user *)user_addr, bad_stack,
96 unconst + sizeof(good_stack))) {
97 pr_warn("copy_to_user failed, but lacked Oops\n");
98 goto free_user;
99 }
100 } else {
101 /*
102 * There isn't a safe way to not be protected by usercopy
103 * if we're going to write to another thread's stack.
104 */
105 if (!bad_frame)
106 goto free_user;
107
108 pr_info("attempting good copy_from_user of local stack\n");
109 if (copy_from_user(good_stack, (void __user *)user_addr,
110 unconst + sizeof(good_stack))) {
111 pr_warn("copy_from_user failed unexpectedly?!\n");
112 goto free_user;
113 }
114
115 pr_info("attempting bad copy_from_user of distant stack\n");
116 if (copy_from_user(bad_stack, (void __user *)user_addr,
117 unconst + sizeof(good_stack))) {
118 pr_warn("copy_from_user failed, but lacked Oops\n");
119 goto free_user;
120 }
121 }
122
123 free_user:
124 vm_munmap(user_addr, PAGE_SIZE);
125 }
126

---
0-DAY CI Kernel Test Service, Intel Corporation