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task_stack: Fix end_of_stack() for architectures with upwards-growing stack

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[ Upstream commit 9cc2fa4f4a ]

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>
This commit is contained in:
Helge Deller 2021-10-05 00:05:43 +02:00 • committed by Greg Kroah-Hartman
commit 50a2d1229b
1 changed files with 4 additions and 0 deletions
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4
include/linux/sched/task_stack.h
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@ -25,7 +25,11 @@ static inline void *task_stack_page(const struct task_struct *task)
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)