forked from Minki/linux
lkdtm: Add CONFIG hints in errors where possible
For various failure conditions, try to include some details about where to look for reasons about the failure. Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210623203936.3151093-8-keescook@chromium.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -303,8 +303,10 @@ void lkdtm_CORRUPT_LIST_ADD(void)
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if (target[0] == NULL && target[1] == NULL)
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pr_err("Overwrite did not happen, but no BUG?!\n");
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else
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else {
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pr_err("list_add() corruption not detected!\n");
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pr_expected_config(CONFIG_DEBUG_LIST);
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}
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}
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void lkdtm_CORRUPT_LIST_DEL(void)
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@ -328,8 +330,10 @@ void lkdtm_CORRUPT_LIST_DEL(void)
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if (target[0] == NULL && target[1] == NULL)
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pr_err("Overwrite did not happen, but no BUG?!\n");
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else
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else {
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pr_err("list_del() corruption not detected!\n");
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pr_expected_config(CONFIG_DEBUG_LIST);
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}
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}
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/* Test that VMAP_STACK is actually allocating with a leading guard page */
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@ -38,5 +38,6 @@ void lkdtm_CFI_FORWARD_PROTO(void)
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func = (void *)lkdtm_increment_int;
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func(&called_count);
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pr_info("Fail: survived mismatched prototype function call!\n");
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pr_err("FAIL: survived mismatched prototype function call!\n");
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pr_expected_config(CONFIG_CFI_CLANG);
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}
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@ -26,6 +26,7 @@
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/debugfs.h>
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#include <linux/init.h>
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#define DEFAULT_COUNT 10
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@ -398,6 +399,56 @@ static ssize_t direct_entry(struct file *f, const char __user *user_buf,
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return count;
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}
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#ifndef MODULE
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/*
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* To avoid needing to export parse_args(), just don't use this code
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* when LKDTM is built as a module.
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*/
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struct check_cmdline_args {
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const char *param;
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int value;
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};
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static int lkdtm_parse_one(char *param, char *val,
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const char *unused, void *arg)
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{
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struct check_cmdline_args *args = arg;
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/* short circuit if we already found a value. */
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if (args->value != -ESRCH)
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return 0;
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if (strncmp(param, args->param, strlen(args->param)) == 0) {
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bool bool_result;
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int ret;
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ret = kstrtobool(val, &bool_result);
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if (ret == 0)
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args->value = bool_result;
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}
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return 0;
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}
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int lkdtm_check_bool_cmdline(const char *param)
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{
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char *command_line;
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struct check_cmdline_args args = {
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.param = param,
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.value = -ESRCH,
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};
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command_line = kstrdup(saved_command_line, GFP_KERNEL);
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if (!command_line)
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return -ENOMEM;
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parse_args("Setting sysctl args", command_line,
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NULL, 0, -1, -1, &args, lkdtm_parse_one);
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kfree(command_line);
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return args.value;
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}
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#endif
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static struct dentry *lkdtm_debugfs_root;
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static int __init lkdtm_module_init(void)
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@ -76,7 +76,8 @@ void lkdtm_FORTIFIED_STRSCPY(void)
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*/
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strscpy(dst, src, strlen(src));
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pr_warn("FAIL: No overflow in above strscpy()\n");
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pr_err("FAIL: strscpy() overflow not detected!\n");
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pr_expected_config(CONFIG_FORTIFY_SOURCE);
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kfree(src);
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}
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@ -109,9 +109,10 @@ void lkdtm_READ_AFTER_FREE(void)
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if (saw != *val) {
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/* Good! Poisoning happened, so declare a win. */
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pr_info("Memory correctly poisoned (%x)\n", saw);
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BUG();
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} else {
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pr_err("FAIL: Memory was not poisoned!\n");
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pr_expected_config_param(CONFIG_INIT_ON_FREE_DEFAULT_ON, "init_on_free");
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}
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pr_info("Memory was not poisoned\n");
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kfree(val);
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}
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@ -165,9 +166,10 @@ void lkdtm_READ_BUDDY_AFTER_FREE(void)
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if (saw != *val) {
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/* Good! Poisoning happened, so declare a win. */
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pr_info("Memory correctly poisoned (%x)\n", saw);
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BUG();
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} else {
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pr_err("FAIL: Buddy page was not poisoned!\n");
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pr_expected_config_param(CONFIG_INIT_ON_FREE_DEFAULT_ON, "init_on_free");
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}
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pr_info("Buddy page was not poisoned\n");
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kfree(val);
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}
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@ -6,6 +6,47 @@
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#include <linux/kernel.h>
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#define pr_expected_config(kconfig) \
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{ \
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if (IS_ENABLED(kconfig)) \
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pr_err("Unexpected! This kernel was built with " #kconfig "=y\n"); \
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else \
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pr_warn("This is probably expected, since this kernel was built *without* " #kconfig "=y\n"); \
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}
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#ifndef MODULE
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int lkdtm_check_bool_cmdline(const char *param);
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#define pr_expected_config_param(kconfig, param) \
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{ \
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if (IS_ENABLED(kconfig)) { \
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switch (lkdtm_check_bool_cmdline(param)) { \
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case 0: \
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pr_warn("This is probably expected, since this kernel was built with " #kconfig "=y but booted with '" param "=N'\n"); \
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break; \
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case 1: \
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pr_err("Unexpected! This kernel was built with " #kconfig "=y and booted with '" param "=Y'\n"); \
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break; \
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default: \
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pr_err("Unexpected! This kernel was built with " #kconfig "=y (and booted without '" param "' specified)\n"); \
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} \
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} else { \
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switch (lkdtm_check_bool_cmdline(param)) { \
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case 0: \
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pr_warn("This is probably expected, as kernel was built *without* " #kconfig "=y and booted with '" param "=N'\n"); \
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break; \
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case 1: \
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pr_err("Unexpected! This kernel was built *without* " #kconfig "=y but booted with '" param "=Y'\n"); \
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break; \
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default: \
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pr_err("This is probably expected, since this kernel was built *without* " #kconfig "=y (and booted without '" param "' specified)\n"); \
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break; \
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} \
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} \
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}
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#else
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#define pr_expected_config_param(kconfig, param) pr_expected_config(kconfig)
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#endif
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/* bugs.c */
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void __init lkdtm_bugs_init(int *recur_param);
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void lkdtm_PANIC(void);
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@ -74,8 +74,8 @@ void lkdtm_STACKLEAK_ERASING(void)
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end:
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if (test_failed) {
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pr_err("FAIL: the thread stack is NOT properly erased\n");
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dump_stack();
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pr_err("FAIL: the thread stack is NOT properly erased!\n");
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pr_expected_config(CONFIG_GCC_PLUGIN_STACKLEAK);
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} else {
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pr_info("OK: the rest of the thread stack is properly erased\n");
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}
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@ -173,6 +173,8 @@ static void do_usercopy_heap_size(bool to_user)
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goto free_user;
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}
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}
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pr_err("FAIL: bad usercopy not detected!\n");
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pr_expected_config_param(CONFIG_HARDENED_USERCOPY, "hardened_usercopy");
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free_user:
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vm_munmap(user_addr, PAGE_SIZE);
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@ -248,6 +250,8 @@ static void do_usercopy_heap_whitelist(bool to_user)
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goto free_user;
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}
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}
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pr_err("FAIL: bad usercopy not detected!\n");
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pr_expected_config_param(CONFIG_HARDENED_USERCOPY, "hardened_usercopy");
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free_user:
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vm_munmap(user_alloc, PAGE_SIZE);
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@ -319,7 +323,8 @@ void lkdtm_USERCOPY_KERNEL(void)
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pr_warn("copy_to_user failed, but lacked Oops\n");
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goto free_user;
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}
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pr_err("FAIL: survived bad copy_to_user()\n");
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pr_err("FAIL: bad copy_to_user() not detected!\n");
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pr_expected_config_param(CONFIG_HARDENED_USERCOPY, "hardened_usercopy");
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free_user:
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vm_munmap(user_addr, PAGE_SIZE);
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@ -30,6 +30,7 @@ rm -f "$log"
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# We would expect any functional stack randomization to be at least 5 bits.
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if [ "$bits" -lt 5 ]; then
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echo "Stack entropy is low! Booted without 'randomize_kstack_offset=y'?"
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exit 1
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else
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exit 0
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