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

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Make sure trashcan pointer look mortal -- 32 bit
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Mark Shannon 2025-05-05 20:51:32 +01:00 • committed by GitHub
parent 9434709edf
commit d48616e08c
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1 changed files with 9 additions and 0 deletions
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9
Objects/object.c
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@ -2940,20 +2940,29 @@ pointer_to_safe_refcount(void *ptr)
{ {
uintptr_t full = (uintptr_t)ptr; uintptr_t full = (uintptr_t)ptr;
assert((full & 3) == 0); assert((full & 3) == 0);
#if SIZEOF_VOID_P > 4
uint32_t refcnt = (uint32_t)full; uint32_t refcnt = (uint32_t)full;
if (refcnt >= (uint32_t)_Py_IMMORTAL_MINIMUM_REFCNT) { if (refcnt >= (uint32_t)_Py_IMMORTAL_MINIMUM_REFCNT) {
full = full - ((uintptr_t)_Py_IMMORTAL_MINIMUM_REFCNT) + 1; full = full - ((uintptr_t)_Py_IMMORTAL_MINIMUM_REFCNT) + 1;
} }
return full + 2; return full + 2;
#else
// Make the top two bits 0, so it appears mortal.
return (full >> 2) + 1;
#endif
} }
static void * static void *
safe_refcount_to_pointer(uintptr_t refcnt) safe_refcount_to_pointer(uintptr_t refcnt)
{ {
#if SIZEOF_VOID_P > 4
if (refcnt & 1) { if (refcnt & 1) {
refcnt += _Py_IMMORTAL_MINIMUM_REFCNT - 1; refcnt += _Py_IMMORTAL_MINIMUM_REFCNT - 1;
} }
return (void *)(refcnt - 2); return (void *)(refcnt - 2);
#else
return (void *)((refcnt -1) << 2);
#endif
} }
#endif #endif