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Fix signed overflow UB in PseudoRandom::next()

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DS 2024-01-19 11:52:53 +01:00 committed by GitHub
parent 7c9706fdcf
commit e416c99419
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1 changed files with 4 additions and 3 deletions
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7
src/noise.h
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@ -56,8 +56,9 @@ public:
inline u32 next() inline u32 next()
{ {
m_next = m_next * 1103515245 + 12345; m_next = static_cast<u32>(m_next) * 1103515245U + 12345U;
return (u32)(m_next / 65536) % (RANDOM_RANGE + 1); // Signed division is required due to backwards compatibility
return static_cast<u32>(m_next / 65536) % (RANDOM_RANGE + 1U);
} }
inline s32 range(s32 min, s32 max) inline s32 range(s32 min, s32 max)
@ -70,7 +71,7 @@ public:
PcgRandom, we cannot modify this RNG's range as it would change the PcgRandom, we cannot modify this RNG's range as it would change the
output of this RNG for reverse compatibility. output of this RNG for reverse compatibility.
*/ */
if ((u32)(max - min) > (RANDOM_RANGE + 1) / 5) if (static_cast<u32>(max - min) > (RANDOM_RANGE + 1) / 5)
throw PrngException("Range too large"); throw PrngException("Range too large");
return (next() % (max - min + 1)) + min; return (next() % (max - min + 1)) + min;