How difficult would it be to create a unit test around this bug to prove what it fixes?
On Monday, January 15, 2018 at 12:52:24 PM UTC-5, Timmons C. Player wrote: > > The page_range_allocator attempts to merge neighbor page ranges > when a page range is freed in order to minimize memory fragmentation. > > However, the original implementation didn't validate indexes before > checking the _bitset to determine whether a page range had a neighbor > or not. This change make sure that indexes stay within bounds. > > This is the correct fix for the fix attempted in > 44f8324e3f2e53f55022a1d93c8b072514e7ac07 > > Signed-off-by: Timmons C. Player <[email protected] <javascript:>> > --- > core/mempool.cc | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/core/mempool.cc b/core/mempool.cc > index e0d0867..1ac3f67 100644 > --- a/core/mempool.cc > +++ b/core/mempool.cc > @@ -761,13 +761,15 @@ page_range* > page_range_allocator::alloc_aligned(size_t size, size_t offset, > > void page_range_allocator::free(page_range* pr) > { > - if (_bitmap[get_bitmap_idx(*pr) - 1]) { > + auto idx = get_bitmap_idx(*pr); > + if (idx && _bitmap[idx - 1]) { > auto pr2 = *(reinterpret_cast<page_range**>(pr) - 1); > remove(*pr2); > pr2->size += pr->size; > pr = pr2; > } > - if (_bitmap[get_bitmap_idx(*pr) + pr->size / page_size - 1]) { > + auto next_idx = get_bitmap_idx(*pr) + pr->size / page_size; > + if (next_idx < _bitmap.size() && _bitmap[next_idx]) { > auto pr2 = static_cast<page_range*>(static_cast<void*>(pr) + > pr->size); > remove(*pr2); > pr->size += pr2->size; > -- > 2.7.4 > > -- You received this message because you are subscribed to the Google Groups "OSv Development" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
