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gh-160162: Fix crash in int left shift with huge count on 32-bit - #160163
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Bound the shift count by MAX_LONG_DIGITS*PyLong_SHIFT instead of PY_SSIZE_T_MAX*PyLong_SHIFT, so that the result size computed in long_lshift1() cannot overflow Py_ssize_t.
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needs backport to 3.14
gpshead
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October 22, 2026 03:49
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Thanks @gpshead for the PR 🌮🎉.. I'm working now to backport this PR to: 3.14, 3.15. |
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GH-160169 is a backport of this pull request to the 3.15 branch. |
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GH-160170 is a backport of this pull request to the 3.14 branch. |
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…it (GH-160163) (#160170) gh-160162: Fix crash in int left shift with huge count on 32-bit (GH-160163) Bound the shift count by MAX_LONG_DIGITS*PyLong_SHIFT instead of PY_SSIZE_T_MAX*PyLong_SHIFT, so that the result size computed in long_lshift1() cannot overflow Py_ssize_t. (cherry picked from commit d4750a7) Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
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Oct 22, 2026
…it (GH-160163) (#160169) gh-160162: Fix crash in int left shift with huge count on 32-bit (GH-160163) Bound the shift count by MAX_LONG_DIGITS*PyLong_SHIFT instead of PY_SSIZE_T_MAX*PyLong_SHIFT, so that the result size computed in long_lshift1() cannot overflow Py_ssize_t. (cherry picked from commit d4750a7) Co-authored-by: Gregory P. Smith <68491+gpshead@users.noreply.github.com>
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Tighten the existing 32-bit-only bound on the shift count in
long_lshift_int64()fromPY_SSIZE_T_MAX * PyLong_SHIFTtoMAX_LONG_DIGITS * PyLong_SHIFT. Any word shift aboveMAX_LONG_DIGITScould never be allocated anyway, and with it boundedoldsize + wordshift + 1cannot overflowPy_ssize_t, solong_lshift1()stays unchanged and 64-bit builds are unaffected (the check is compiled out there).The crash only reproduces on 32-bit builds; on 64-bit the new test passes before and after the fix because those counts already overflow
int64_t.ANT-2026-9YXRBW87