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GH-133261: Make sure trashcan pointers look mortal -- 32 bit #133450

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Merged
merged 1 commit into from
May 5, 2025
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GH-133261: Make sure trashcan pointers look mortal -- 32 bit #133450

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9 changes: 9 additions & 0 deletions Objects/object.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2940,20 +2940,29 @@ pointer_to_safe_refcount(void *ptr)
{
uintptr_t full = (uintptr_t)ptr;
assert((full & 3) == 0);
#if SIZEOF_VOID_P > 4
uint32_t refcnt = (uint32_t)full;
if (refcnt >= (uint32_t)_Py_IMMORTAL_MINIMUM_REFCNT) {
full = full - ((uintptr_t)_Py_IMMORTAL_MINIMUM_REFCNT) + 1;
}
return full + 2;
#else
// Make the top two bits 0, so it appears mortal.
return (full >> 2) + 1;
#endif
}

static void *
safe_refcount_to_pointer(uintptr_t refcnt)
{
#if SIZEOF_VOID_P > 4
if (refcnt & 1) {
refcnt += _Py_IMMORTAL_MINIMUM_REFCNT - 1;
}
return (void *)(refcnt - 2);
#else
return (void *)((refcnt -1) << 2);
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Suggested change
return (void *)((refcnt -1) << 2);
return (void *)((refcnt - 1) << 2);

#endif
}
#endif

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