Fix: possible overflow when using non-standard Dataset size #87
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hyc
reviewed
Jun 25, 2019
| @@ -43,6 +43,7 @@ namespace randomx { | |||
| static_assert((RANDOMX_DATASET_BASE_SIZE & (RANDOMX_DATASET_BASE_SIZE - 1)) == 0, "RANDOMX_DATASET_BASE_SIZE must be a power of 2."); | |||
| static_assert(RANDOMX_DATASET_BASE_SIZE <= 4294967296ULL, "RANDOMX_DATASET_BASE_SIZE must not exceed 4294967296."); | |||
| static_assert(RANDOMX_DATASET_EXTRA_SIZE % 64 == 0, "RANDOMX_DATASET_EXTRA_SIZE must be divisible by 64."); | |||
| static_assert((uint64_t)RANDOMX_DATASET_BASE_SIZE + RANDOMX_DATASET_EXTRA_SIZE <= 17179869184, "Dataset size must not exceed 16 GiB."); | |||
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Is 16GB an arbitrary limit? Why do we need this limit?
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The theoretical maximum is 256 GiB, because at that point dataset indexes will start to overflow.
But the maximum portion of the Dataset that is used by a program is 4 GiB, so it doesn't make much sense to have a very large Dataset. 16 GiB is an arbitrary limit to make sure RandomX is not used with broken parameters.
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Overflow is possible here if Dataset size is over 4 GiB.
RandomX/src/randomx.cpp
Line 123 in 2706a8b
Also added a
static_assertto limit Dataset to a maximum of 16 GiB.