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Kernel: Create and use USER_RANGE_CEILING

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We had an inconsistency in valid user addresses. is_user_range() was
checking against the kernel base address, but previous changes caused
the maximum valid user addressable range to be 32 MiB below that.

This patch stops mmap(MAP_FIXED) of a range between these two bounds
from panic-ing the kernel in RangeAllocator::allocate_specific.
This commit is contained in:
Andrew Kaster 2021-07-06 20:25:22 -06:00 • committed by Andreas Kling
parent ab196b484a
commit 578d45b480
3 changed files with 4 additions and 2 deletions
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2
Kernel/VM/MemoryManager.h
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@ -278,7 +278,7 @@ void VMObject::for_each_region(Callback callback)
inline bool is_user_address(VirtualAddress vaddr)
{
return vaddr.get() < KERNEL_BASE;
return vaddr.get() < USER_RANGE_CEILING;
}
inline bool is_user_range(VirtualAddress vaddr, size_t size)

2
Kernel/VM/PageDirectory.cpp
View file

@ -63,7 +63,7 @@ UNMAP_AFTER_INIT void PageDirectory::allocate_kernel_directory()
PageDirectory::PageDirectory(const RangeAllocator* parent_range_allocator)
{
constexpr FlatPtr userspace_range_base = 0x00800000;
constexpr FlatPtr userspace_range_ceiling = 0xbe000000;
constexpr FlatPtr userspace_range_ceiling = USER_RANGE_CEILING;
ScopedSpinLock lock(s_mm_lock);
if (parent_range_allocator) {