Fix int32_t overflow in intl_charFromString() capacity calculation#22427
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iliaal wants to merge 1 commit into
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Fix int32_t overflow in intl_charFromString() capacity calculation#22427iliaal wants to merge 1 commit into
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intl_charFromString() computed the UTF-8 output capacity as from.length() * 3 in int32_t arithmetic. For a UnicodeString longer than INT32_MAX/3 UTF-16 units the multiply overflows (UB); capacity can go negative, making zend_string_alloc() request a near-SIZE_MAX block, or wrap small, undersizing the buffer that u_strToUTF8WithSub() then writes into. Reject the over-long input with U_BUFFER_OVERFLOW_ERROR up front, mirroring the existing INT32_MAX guard in the sibling intl_stringFromChar().
LamentXU123
approved these changes
Jun 24, 2026
devnexen
approved these changes
Jun 24, 2026
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intl_charFromString() computed the UTF-8 output capacity as from.length() * 3 in int32_t arithmetic. For a UnicodeString longer than INT32_MAX/3 UTF-16 code units the multiply overflows: capacity can go negative (zend_string_alloc() then requests a near-SIZE_MAX block) or wrap small, undersizing the buffer that u_strToUTF8WithSub() writes into. Reject the over-long input with U_BUFFER_OVERFLOW_ERROR up front, mirroring the INT32_MAX guard already present in the sibling intl_stringFromChar(). The input is always ICU-produced output, so triggering needs a multi-GB UnicodeString; there is no portable red/green test, and the fix matches the project's symmetric-path convention.