Fix panic in Int::div_rem_unsigned with large divisors#1250
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cong-or wants to merge 1 commit intoRustCrypto:masterfrom
Open
Fix panic in Int::div_rem_unsigned with large divisors#1250cong-or wants to merge 1 commit intoRustCrypto:masterfrom
cong-or wants to merge 1 commit intoRustCrypto:masterfrom
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panics when the remainder's magnitude doesn't fit in , which happens when the divisor is large enough. Use instead, matching the vartime path. Fixes RustCrypto#847
Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## master #1250 +/- ##
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+ Coverage 87.99% 90.87% +2.88%
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Files 184 186 +2
Lines 21244 21609 +365
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+ Hits 18693 19638 +945
+ Misses 2551 1971 -580 ☔ View full report in Codecov by Sentry. 🚀 New features to boost your workflow:
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Fix ct
div_rem_unsignedblowing up on large divisorsRan into this while poking at something unrelated.
The constant-time
div_rem_unsignedbreaks when the divisor gets big enough(e.g. any
U128>I128::MAX), since the remainder can’t fit in a signedint of the same size. The ct path was going through
new_from_abs_sign,which ends up blowing up in that case.
The vartime version doesn’t have this issue since it just uses
as_int().wrapping_neg_if(), so this switches the ct path to do the same.Added a test with the values from the issue to make sure it doesn’t regress.
Fixes #847