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-rw-r--r--drivers/misc/lkdtm/bugs.c77
-rw-r--r--drivers/misc/lkdtm/core.c1
-rw-r--r--drivers/misc/lkdtm/lkdtm.h1
3 files changed, 79 insertions, 0 deletions
diff --git a/drivers/misc/lkdtm/bugs.c b/drivers/misc/lkdtm/bugs.c
index 4282b625200f..f4cb94a9aa9c 100644
--- a/drivers/misc/lkdtm/bugs.c
+++ b/drivers/misc/lkdtm/bugs.c
@@ -151,6 +151,83 @@ void lkdtm_REPORT_STACK(void)
pr_info("Stack offset: %d\n", (int)(stack_addr - (uintptr_t)&magic));
}
+static pid_t stack_canary_pid;
+static unsigned long stack_canary;
+static unsigned long stack_canary_offset;
+
+static noinline void __lkdtm_REPORT_STACK_CANARY(void *stack)
+{
+ int i = 0;
+ pid_t pid = task_pid_nr(current);
+ unsigned long *canary = (unsigned long *)stack;
+ unsigned long current_offset = 0, init_offset = 0;
+
+ /* Do our best to find the canary in a 16 word window ... */
+ for (i = 1; i < 16; i++) {
+ canary = (unsigned long *)stack + i;
+#ifdef CONFIG_STACKPROTECTOR
+ if (*canary == current->stack_canary)
+ current_offset = i;
+ if (*canary == init_task.stack_canary)
+ init_offset = i;
+#endif
+ }
+
+ if (current_offset == 0) {
+ /*
+ * If the canary doesn't match what's in the task_struct,
+ * we're either using a global canary or the stack frame
+ * layout changed.
+ */
+ if (init_offset != 0) {
+ pr_err("FAIL: global stack canary found at offset %ld (canary for pid %d matches init_task's)!\n",
+ init_offset, pid);
+ } else {
+ pr_warn("FAIL: did not correctly locate stack canary :(\n");
+ pr_expected_config(CONFIG_STACKPROTECTOR);
+ }
+
+ return;
+ } else if (init_offset != 0) {
+ pr_warn("WARNING: found both current and init_task canaries nearby?!\n");
+ }
+
+ canary = (unsigned long *)stack + current_offset;
+ if (stack_canary_pid == 0) {
+ stack_canary = *canary;
+ stack_canary_pid = pid;
+ stack_canary_offset = current_offset;
+ pr_info("Recorded stack canary for pid %d at offset %ld\n",
+ stack_canary_pid, stack_canary_offset);
+ } else if (pid == stack_canary_pid) {
+ pr_warn("ERROR: saw pid %d again -- please use a new pid\n", pid);
+ } else {
+ if (current_offset != stack_canary_offset) {
+ pr_warn("ERROR: canary offset changed from %ld to %ld!?\n",
+ stack_canary_offset, current_offset);
+ return;
+ }
+
+ if (*canary == stack_canary) {
+ pr_warn("FAIL: canary identical for pid %d and pid %d at offset %ld!\n",
+ stack_canary_pid, pid, current_offset);
+ } else {
+ pr_info("ok: stack canaries differ between pid %d and pid %d at offset %ld.\n",
+ stack_canary_pid, pid, current_offset);
+ /* Reset the test. */
+ stack_canary_pid = 0;
+ }
+ }
+}
+
+void lkdtm_REPORT_STACK_CANARY(void)
+{
+ /* Use default char array length that triggers stack protection. */
+ char data[8] __aligned(sizeof(void *)) = { };
+
+ __lkdtm_REPORT_STACK_CANARY((void *)&data);
+}
+
void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void)
{
static u8 data[5] __attribute__((aligned(4))) = {1, 2, 3, 4, 5};
diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index fe6fd34b8caf..609d9ee2acc0 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -111,6 +111,7 @@ static const struct crashtype crashtypes[] = {
CRASHTYPE(CORRUPT_STACK),
CRASHTYPE(CORRUPT_STACK_STRONG),
CRASHTYPE(REPORT_STACK),
+ CRASHTYPE(REPORT_STACK_CANARY),
CRASHTYPE(CORRUPT_LIST_ADD),
CRASHTYPE(CORRUPT_LIST_DEL),
CRASHTYPE(STACK_GUARD_PAGE_LEADING),
diff --git a/drivers/misc/lkdtm/lkdtm.h b/drivers/misc/lkdtm/lkdtm.h
index c212a253edde..d6137c70ebbe 100644
--- a/drivers/misc/lkdtm/lkdtm.h
+++ b/drivers/misc/lkdtm/lkdtm.h
@@ -69,6 +69,7 @@ void lkdtm_EXHAUST_STACK(void);
void lkdtm_CORRUPT_STACK(void);
void lkdtm_CORRUPT_STACK_STRONG(void);
void lkdtm_REPORT_STACK(void);
+void lkdtm_REPORT_STACK_CANARY(void);
void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void);
void lkdtm_SOFTLOCKUP(void);
void lkdtm_HARDLOCKUP(void);