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gh-126024: fix UBSan failure in unicodeobject.c:find_first_nonascii #127566

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Merged
merged 5 commits into from
Dec 6, 2024
Merged

gh-126024: fix UBSan failure in unicodeobject.c:find_first_nonascii #127566

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947fcfa
fix UBSan failure in `unicodeobject.c`
picnixz Dec 3, 2024
8d8fe33
fix compilation?
picnixz Dec 3, 2024
a807b63
simplify if-guards
picnixz Dec 3, 2024
c6af019
use memcpy() instead of `no_sanitize` features
picnixz Dec 5, 2024
5b957a8
Use `memcpy` on non-x86/amd64 little-endian platforms.
picnixz Dec 5, 2024
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6 changes: 4 additions & 2 deletions Objects/unicodeobject.c
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Original file line number Diff line number Diff line change
Expand Up @@ -5083,11 +5083,13 @@ find_first_nonascii(const unsigned char *start, const unsigned char *end)
const unsigned char *p2 = _Py_ALIGN_UP(p, SIZEOF_SIZE_T);
#if PY_LITTLE_ENDIAN && HAVE_CTZ
if (p < p2) {
size_t u;
#if defined(_M_AMD64) || defined(_M_IX86) || defined(__x86_64__) || defined(__i386__)
// x86 and amd64 are little endian and can load unaligned memory.
size_t u = *(const size_t*)p & ASCII_CHAR_MASK;
memcpy(&u, p, sizeof(size_t));
u &= ASCII_CHAR_MASK;
#else
size_t u = load_unaligned(p, p2 - p) & ASCII_CHAR_MASK;
u = load_unaligned(p, p2 - p) & ASCII_CHAR_MASK;
#endif
if (u) {
return (ctz(u) - 7) / 8;
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