kprobes: Prohibit probing on BUG() and WARN() address

Hi Masami,

I love your patch! Perhaps something to improve:

[auto build test WARNING on linus/master]
[cannot apply to v5.3-rc6 next-20190902]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Masami-Hiramatsu/kprobes-Prohibit-probing-on-BUG-and-WARN-address/20190902-211736
config: powerpc-defconfig (attached as .config)
compiler: powerpc64-linux-gcc (GCC) 7.4.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.4.0 make.cross ARCH=powerpc

If you fix the issue, kindly add following tag

All warnings (new ones prefixed by >>):

kernel/kprobes.c: In function 'check_kprobe_address_safe':

>> kernel/kprobes.c:1518:15: warning: passing argument 1 of 'find_bug' makes integer from pointer without a cast [-Wint-conversion]
         find_bug(p->addr)) {
                  ^
   In file included from arch/powerpc/include/asm/mmu.h:130:0,
                    from arch/powerpc/include/asm/lppaca.h:47,
                    from arch/powerpc/include/asm/paca.h:17,
                    from arch/powerpc/include/asm/current.h:13,
                    from include/linux/mutex.h:14,
                    from include/linux/notifier.h:14,
                    from include/linux/kprobes.h:22,
                    from kernel/kprobes.c:21:
   include/linux/bug.h:39:19: note: expected 'long unsigned int' but argument is of type 'kprobe_opcode_t * {aka unsigned int *}'
    struct bug_entry *find_bug(unsigned long bugaddr);
                      ^~~~~~~~

vim +/find_bug +1518 kernel/kprobes.c

1502
1503 static int check_kprobe_address_safe(struct kprobe *p,
1504 struct module **probed_mod)
1505 {
1506 int ret;
1507
1508 ret = arch_check_ftrace_location(p);
1509 if (ret)
1510 return ret;
1511 jump_label_lock();
1512 preempt_disable();
1513
1514 /* Ensure it is not in reserved area nor out of text */
1515 if (!kernel_text_address((unsigned long) p->addr) ||

  1516		    within_kprobe_blacklist((unsigned long) p->addr) ||
  1517		    jump_label_text_reserved(p->addr, p->addr) ||
> 1518		    find_bug(p->addr)) {

1519 ret = -EINVAL;
1520 goto out;
1521 }
1522
1523 /* Check if are we probing a module */
1524 *probed_mod = __module_text_address((unsigned long) p->addr);
1525 if (*probed_mod) {
1526 /*
1527 * We must hold a refcount of the probed module while updating
1528 * its code to prohibit unexpected unloading.
1529 */
1530 if (unlikely(!try_module_get(*probed_mod))) {
1531 ret = -ENOENT;
1532 goto out;
1533 }
1534
1535 /*
1536 * If the module freed .init.text, we couldn't insert
1537 * kprobes in there.
1538 */
1539 if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1540 (*probed_mod)->state != MODULE_STATE_COMING) {
1541 module_put(*probed_mod);
1542 *probed_mod = NULL;
1543 ret = -ENOENT;
1544 }
1545 }
1546 out:
1547 preempt_enable();
1548 jump_label_unlock();
1549
1550 return ret;
1551 }
1552

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation

Hi Masami,

I love your patch! Yet something to improve:

[auto build test ERROR on linus/master]
[cannot apply to v5.3-rc6 next-20190902]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Masami-Hiramatsu/kprobes-Prohibit-probing-on-BUG-and-WARN-address/20190902-211736
config: sparc64-allmodconfig (attached as .config)
compiler: sparc64-linux-gcc (GCC) 7.4.0
reproduce:
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
GCC_VERSION=7.4.0 make.cross ARCH=sparc64

If you fix the issue, kindly add following tag

All errors (new ones prefixed by >>):

kernel/kprobes.c: In function 'check_kprobe_address_safe':

>> kernel/kprobes.c:1518:6: error: implicit declaration of function 'find_bug'; did you mean 'find_vma'? [-Werror=implicit-function-declaration]
         find_bug(p->addr)) {
         ^~~~~~~~
         find_vma

cc1: some warnings being treated as errors

vim +1518 kernel/kprobes.c

1502
1503 static int check_kprobe_address_safe(struct kprobe *p,
1504 struct module **probed_mod)
1505 {
1506 int ret;
1507
1508 ret = arch_check_ftrace_location(p);
1509 if (ret)
1510 return ret;
1511 jump_label_lock();
1512 preempt_disable();
1513
1514 /* Ensure it is not in reserved area nor out of text */
1515 if (!kernel_text_address((unsigned long) p->addr) ||

  1516		    within_kprobe_blacklist((unsigned long) p->addr) ||
  1517		    jump_label_text_reserved(p->addr, p->addr) ||
> 1518		    find_bug(p->addr)) {

1519 ret = -EINVAL;
1520 goto out;
1521 }
1522
1523 /* Check if are we probing a module */
1524 *probed_mod = __module_text_address((unsigned long) p->addr);
1525 if (*probed_mod) {
1526 /*
1527 * We must hold a refcount of the probed module while updating
1528 * its code to prohibit unexpected unloading.
1529 */
1530 if (unlikely(!try_module_get(*probed_mod))) {
1531 ret = -ENOENT;
1532 goto out;
1533 }
1534
1535 /*
1536 * If the module freed .init.text, we couldn't insert
1537 * kprobes in there.
1538 */
1539 if (within_module_init((unsigned long)p->addr, *probed_mod) &&
1540 (*probed_mod)->state != MODULE_STATE_COMING) {
1541 module_put(*probed_mod);
1542 *probed_mod = NULL;
1543 ret = -ENOENT;
1544 }
1545 }
1546 out:
1547 preempt_enable();
1548 jump_label_unlock();
1549
1550 return ret;
1551 }
1552

---
0-DAY kernel test infrastructure Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all Intel Corporation