From: Helge Deller Date: Mon, 4 Oct 2021 22:05:43 +0000 (+0200) Subject: task_stack: Fix end_of_stack() for architectures with upwards-growing stack X-Git-Tag: Ubuntu-5.4.0-98.111~583 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=1928a484479468116d8a5c44c0ed1aeece1c7e2c;p=mirror_ubuntu-focal-kernel.git task_stack: Fix end_of_stack() for architectures with upwards-growing stack BugLink: https://bugs.launchpad.net/bugs/1953387 [ 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 Signed-off-by: Sasha Levin Signed-off-by: Kamal Mostafa Signed-off-by: Kelsey Skunberg --- diff --git a/include/linux/sched/task_stack.h b/include/linux/sched/task_stack.h index 2413427e439c..d10150587d81 100644 --- a/include/linux/sched/task_stack.h +++ b/include/linux/sched/task_stack.h @@ -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)