ext/bcmath: Prevent overflow of uint32_t/uint64_t#14297
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SakiTakamachi
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If add more than a certain number of times, it will overflow, so need to adjust the digits before adding.
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ndossche
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Nice approach and good catch, thanks!
| # define BC_MUL_UINT_DIGITS 8 | ||
| # define BC_MUL_UINT_OVERFLOW 100000000 | ||
| # define BC_MUL_UINT_OVERFLOW (BC_UINT_T) 100000000 | ||
| # define BC_MUL_MAX_ADD_COUNT (ULONG_MAX / (BC_MUL_UINT_OVERFLOW * BC_MUL_UINT_OVERFLOW)) |
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Note that the size of a long is not necessarily the size of size_t.
I think I prefer a single definition:
#define BC_MUL_MAX_ADD_COUNT (~((BC_UINT_T) 0) / (BC_MUL_UINT_OVERFLOW * BC_MUL_UINT_OVERFLOW))
ndossche
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Seems right to me, thanks Saki!
SakiTakamachi
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I'll merge this after CI passes |
Girgias
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If add more than a certain number of times, it will overflow, so need to adjust the digits before adding.