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Issue #876: Fix integer overflow on slice_count #877

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Issue #876: Fix integer overflow on slice_count #877

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6 changes: 6 additions & 0 deletions src/segment.c
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Original file line number Diff line number Diff line change
Expand Up @@ -820,6 +820,9 @@ static mi_segment_t* mi_segment_os_alloc( size_t required, size_t page_alignment
const size_t extra = align_offset - info_size;
// recalculate due to potential guard pages
*psegment_slices = mi_segment_calculate_slices(required + extra, ppre_size, pinfo_slices);

// gh-876: mi_page_t.slice_count type is uint32_t
if (*psegment_slices > (size_t)UINT32_MAX) return NULL;
}

const size_t segment_size = (*psegment_slices) * MI_SEGMENT_SLICE_SIZE;
Expand Down Expand Up @@ -870,6 +873,9 @@ static mi_segment_t* mi_segment_alloc(size_t required, size_t page_alignment, mi
size_t pre_size;
size_t segment_slices = mi_segment_calculate_slices(required, &pre_size, &info_slices);

// gh-876: mi_page_t.slice_count type is uint32_t
if (segment_slices > (size_t)UINT32_MAX) return NULL;

// Commit eagerly only if not the first N lazy segments (to reduce impact of many threads that allocate just a little)
const bool eager_delay = (// !_mi_os_has_overcommit() && // never delay on overcommit systems
_mi_current_thread_count() > 1 && // do not delay for the first N threads
Expand Down
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