task_stack: Fix end_of_stack() for architectures with upwards-growing stack
[ Upstream commit 9cc2fa4f4a92ccc6760d764e7341be46ee8aaaa1 ]
The function end_of_stack() returns a pointer to the last entry of a
stack. For architectures like parisc where the stack grows upwards
return the pointer to the highest address in the stack.
Without this change I faced a crash on parisc, because the stackleak
functionality wrote STACKLEAK_POISON to the lowest address and thus
overwrote the first 4 bytes of the task_struct which included the
TIF_FLAGS.
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h
index cb4828a..3461beb 100644
--- a/include/linux/sched/task_stack.h
+++ b/include/linux/sched/task_stack.h
@@ -25,7 +25,11 @@
static inline unsigned long *end_of_stack(const struct task_struct *task)
{
+#ifdef CONFIG_STACK_GROWSUP
+ return (unsigned long *)((unsigned long)task->stack + THREAD_SIZE) - 1;
+#else
return task->stack;
+#endif
}
#elif !defined(__HAVE_THREAD_FUNCTIONS)