Merge branch 'stackprotector' into core/percpu

4 files changed, 18 insertions, 11 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index c7740fa3252..2a803c28df9 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -977,12 +977,9 @@ static void check_stack_usage(void)
 {
 	static DEFINE_SPINLOCK(low_water_lock);
 	static int lowest_to_date = THREAD_SIZE;
-	unsigned long *n = end_of_stack(current);
 	unsigned long free;
 
-	while (*n == 0)
-		n++;
-	free = (unsigned long)n - (unsigned long)end_of_stack(current);
+	free = stack_not_used(current);
 
 	if (free >= lowest_to_date)
 		return;
diff --git a/kernel/fork.c b/kernel/fork.c
index 1d68f1255dd..4a9b318dad0 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -61,6 +61,7 @@
 #include <linux/proc_fs.h>
 #include <linux/blkdev.h>
 #include <trace/sched.h>
+#include <linux/magic.h>
 
 #include <asm/pgtable.h>
 #include <asm/pgalloc.h>
@@ -212,6 +213,8 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 {
 	struct task_struct *tsk;
 	struct thread_info *ti;
+	unsigned long *stackend;
+
 	int err;
 
 	prepare_to_copy(orig);
@@ -237,6 +240,8 @@ static struct task_struct *dup_task_struct(struct task_struct *orig)
 		goto out;
 
 	setup_thread_stack(tsk, orig);
+	stackend = end_of_stack(tsk);
+	*stackend = STACK_END_MAGIC;	/* for overflow detection */
 
 #ifdef CONFIG_CC_STACKPROTECTOR
 	tsk->stack_canary = get_random_int();
diff --git a/kernel/panic.c b/kernel/panic.c
index 2a2ff36ff44..33cab3de176 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -74,6 +74,9 @@ NORET_TYPE void panic(const char * fmt, ...)
 	vsnprintf(buf, sizeof(buf), fmt, args);
 	va_end(args);
 	printk(KERN_EMERG "Kernel panic - not syncing: %s\n",buf);
+#ifdef CONFIG_DEBUG_BUGVERBOSE
+	dump_stack();
+#endif
 	bust_spinlocks(0);
 
 	/*
@@ -355,15 +358,22 @@ EXPORT_SYMBOL(warn_slowpath);
 #endif
 
 #ifdef CONFIG_CC_STACKPROTECTOR
+
+#ifndef GCC_HAS_SP
+#warning You have selected the CONFIG_CC_STACKPROTECTOR option, but the gcc used does not support this.
+#endif
+
 /*
  * Called when gcc's -fstack-protector feature is used, and
  * gcc detects corruption of the on-stack canary value
  */
 void __stack_chk_fail(void)
 {
-	panic("stack-protector: Kernel stack is corrupted");
+	panic("stack-protector: Kernel stack is corrupted in: %p\n",
+		__builtin_return_address(0));
 }
 EXPORT_SYMBOL(__stack_chk_fail);
+
 #endif
 
 core_param(panic, panic_timeout, int, 0644);
diff --git a/kernel/sched.c b/kernel/sched.c
index 8be2c13b50d..1d290906704 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5939,12 +5939,7 @@ void sched_show_task(struct task_struct *p)
 		printk(KERN_CONT " %016lx ", thread_saved_pc(p));
 #endif
 #ifdef CONFIG_DEBUG_STACK_USAGE
-	{
-		unsigned long *n = end_of_stack(p);
-		while (!*n)
-			n++;
-		free = (unsigned long)n - (unsigned long)end_of_stack(p);
-	}
+	free = stack_not_used(p);
 #endif
 	printk(KERN_CONT "%5lu %5d %6d\n", free,
 		task_pid_nr(p), task_pid_nr(p->real_parent));