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Kernel: Fix use-after-free in sys$mremap

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Now that Region::name() has been changed to return a StringView we
can't rely on keeping a copy of the region's name past the region's
destruction just by holding a copy of the StringView.
This commit is contained in:
Gunnar Beutner 2021-06-02 11:58:56 +02:00 • committed by Andreas Kling
parent 33cdc59dff
commit fe0ae3161a
2 changed files with 4 additions and 2 deletions
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5
Kernel/Syscalls/mmap.cpp
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@ -536,7 +536,6 @@ KResultOr<FlatPtr> Process::sys$mremap(Userspace<const Syscall::SC_mremap_params
if (old_region->vmobject().is_shared_inode() && params.flags & MAP_PRIVATE && !(params.flags & (MAP_ANONYMOUS | MAP_NORESERVE))) {
auto range = old_region->range();
auto old_name = old_region->name();
auto old_prot = region_access_flags_to_prot(old_region->access());
auto old_offset = old_region->offset_in_vmobject();
NonnullRefPtr inode = static_cast<SharedInodeVMObject&>(old_region->vmobject()).inode();
@ -545,12 +544,14 @@ KResultOr<FlatPtr> Process::sys$mremap(Userspace<const Syscall::SC_mremap_params
if (!new_vmobject)
return ENOMEM;
auto old_name = old_region->take_name();
// Unmap without deallocating the VM range since we're going to reuse it.
old_region->unmap(Region::ShouldDeallocateVirtualMemoryRange::No);
bool success = space().deallocate_region(*old_region);
VERIFY(success);
auto new_region_or_error = space().allocate_region_with_vmobject(range, new_vmobject.release_nonnull(), old_offset, old_name, old_prot, false);
auto new_region_or_error = space().allocate_region_with_vmobject(range, new_vmobject.release_nonnull(), old_offset, old_name->view(), old_prot, false);
if (new_region_or_error.is_error())
return new_region_or_error.error().error();
auto& new_region = *new_region_or_error.value();