Check result of repeat/concat fit in an MVMString #546
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jnthn
reviewed
Mar 8, 2017
| @@ -509,6 +518,13 @@ MVMString * MVM_string_repeat(MVMThreadContext *tc, MVMString *a, MVMint64 count | |||
| if (agraphs == 0) | |||
| return tc->instance->str_consts.empty; | |||
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| /* Total size of the resulting string can't be bigger than an MVMString is allowed to be. */ | |||
| total_graphs = (MVMuint64)agraphs * (MVMuint64)count; | |||
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Since count is a 64-bit integer, it's possible that this bounds check itself could overflow.
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agraphs can't be greater than 0xFFFFFFFF (since num_graphs is a MVMuint32) and we already check that count is not greater than (1 << 30). Should be fine, right?
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Ah, I missed the earlier check on count. Then yeah, this is safe. 👍
MasterDuke17
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add_checks_on_resulting_size_to_string_concatenating_and_repeating
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NQP passes
make m-testand Rakudo passesmake m-spectest.Fixes https://rt.perl.org/Ticket/Display.html?id=127971