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Kernel: Harden sys$munmap Vector usage against OOM.

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Theoretically the append should never fail as we have in-line storage
of 2, which should be enough. However I'm planning on removing the
non-try variants of AK::Vector when compiling in kernel mode in the
future, so this will need to go eventually. I suppose it also protects
against some unforeseen bug where we we can append more than 2 items.
This commit is contained in:
Brian Gianforcaro 2021-04-29 02:20:28 -07:00 • committed by Andreas Kling
parent 569c5a8922
commit 0ca668f59c
1 changed files with 4 additions and 3 deletions
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7
Kernel/Syscalls/mmap.cpp
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@ -505,7 +505,7 @@ KResultOr<int> Process::sys$munmap(Userspace<void*> addr, size_t size)
// slow: without caching // slow: without caching
const auto& regions = space().find_regions_intersecting(range_to_unmap); const auto& regions = space().find_regions_intersecting(range_to_unmap);
// check if any of the regions is not mmapped, to not accientally // Check if any of the regions is not mmapped, to not accidentally
// error-out with just half a region map left // error-out with just half a region map left
for (auto* region : regions) { for (auto* region : regions) {
if (!region->is_mmap()) if (!region->is_mmap())
@ -530,8 +530,9 @@ KResultOr<int> Process::sys$munmap(Userspace<void*> addr, size_t size)
// We manually unmap the old region here, specifying that we *don't* want the VM deallocated. // We manually unmap the old region here, specifying that we *don't* want the VM deallocated.
region->unmap(Region::ShouldDeallocateVirtualMemoryRange::No); region->unmap(Region::ShouldDeallocateVirtualMemoryRange::No);
// otherwise just split the regions and collect them for future mapping // Otherwise just split the regions and collect them for future mapping
new_regions.append(space().split_region_around_range(*region, range_to_unmap)); if (new_regions.try_append(space().split_region_around_range(*region, range_to_unmap)))
return ENOMEM;
} }
// Instead we give back the unwanted VM manually at the end. // Instead we give back the unwanted VM manually at the end.
space().page_directory().range_allocator().deallocate(range_to_unmap); space().page_directory().range_allocator().deallocate(range_to_unmap);