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LibC: Fix bsearch 

bsearch had unsigned integer underflow which was UB and returned false
positives
This commit is contained in:
Bananymous 2025-04-02 00:03:50 +03:00
parent 04463675c0
commit 691c9fe8e0
1 changed files with 8 additions and 6 deletions
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14
userspace/libraries/LibC/stdlib.cpp
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@ -713,24 +713,26 @@ void* bsearch(const void* key, const void* base, size_t nel, size_t width, int (
if (nel == 0) if (nel == 0)
return nullptr; return nullptr;
const uint8_t* base_u8 = reinterpret_cast<const uint8_t*>(base); const uint8_t* base_u8 = static_cast<const uint8_t*>(base);
size_t l = 0; size_t l = 0;
size_t r = nel - 1; size_t r = nel - 1;
while (l <= r) while (l < r)
{ {
const size_t mid = (l + r) / 2; const size_t mid = l + (r - l) / 2;
int res = compar(key, base_u8 + mid * width); int res = compar(key, base_u8 + mid * width);
if (res == 0) if (res == 0)
return const_cast<uint8_t*>(base_u8 + mid * width); return const_cast<uint8_t*>(base_u8 + mid * width);
if (res < 0) if (res > 0)
r = mid - 1;
else
l = mid + 1; l = mid + 1;
else
r = mid ? mid - 1 : 0;
} }
if (l < nel && compar(key, base_u8 + l * width) == 0)
return const_cast<uint8_t*>(base_u8 + l * width);
return nullptr; return nullptr;
} }