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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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#include <linux/sched.h>#include <linux/sched/task_stack.h>
/* * Check that the poison value points to the unused hole in the * virtual memory map for your platform. */#define KSTACK_ERASE_POISON -0xBEEF#define KSTACK_ERASE_SEARCH_DEPTH 128
#ifdef CONFIG_KSTACK_ERASE#include <asm/stacktrace.h>#include <linux/linkage.h>
/* * The lowest address on tsk's stack which we can plausibly erase. */static __always_inline unsigned longstackleak_task_low_bound(const struct task_struct *tsk){ /* * The lowest unsigned long on the task stack contains STACK_END_MAGIC, * which we must not corrupt. */ return (unsigned long)end_of_stack(tsk) + sizeof(unsigned long);}
/* * The address immediately after the highest address on tsk's stack which we * can plausibly erase. */static __always_inline unsigned longstackleak_task_high_bound(const struct task_struct *tsk){ /* * The task's pt_regs lives at the top of the task stack and will be * overwritten by exception entry, so there's no need to erase them. */ return (unsigned long)task_pt_regs(tsk);}
/* * Find the address immediately above the poisoned region of the stack, where * that region falls between 'low' (inclusive) and 'high' (exclusive). */static __always_inline unsigned longstackleak_find_top_of_poison(const unsigned long low, const unsigned long high){ const unsigned int depth = KSTACK_ERASE_SEARCH_DEPTH / sizeof(unsigned long); unsigned int poison_count = 0; unsigned long poison_high = high; unsigned long sp = high;
while (sp > low && poison_count < depth) { sp -= sizeof(unsigned long);
if (*(unsigned long *)sp == KSTACK_ERASE_POISON) { poison_count++; } else { poison_count = 0; poison_high = sp; } }
return poison_high;}
static inline void stackleak_task_init(struct task_struct *t){ t->lowest_stack = stackleak_task_low_bound(t);# ifdef CONFIG_KSTACK_ERASE_METRICS t->prev_lowest_stack = t->lowest_stack;# endif}
asmlinkage void noinstr stackleak_erase(void);asmlinkage void noinstr stackleak_erase_on_task_stack(void);asmlinkage void noinstr stackleak_erase_off_task_stack(void);void __no_caller_saved_registers noinstr __sanitizer_cov_stack_depth(void);
#else /* !CONFIG_KSTACK_ERASE */static inline void stackleak_task_init(struct task_struct *t) { }#endif
#endif