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Kernel: Always reject never-userspace addresses before checking regions

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At the moment, addresses below 8MB and above 3GB are never accessible
to userspace, so just reject them without even looking at the current
process's memory regions.
This commit is contained in:
Andreas Kling 2019-12-31 03:43:24 +01:00
parent 8a0ef92100
commit c9ec415e2f
1 changed files with 11 additions and 0 deletions
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11
Kernel/VM/MemoryManager.cpp
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@ -584,20 +584,31 @@ void MemoryManager::unquickmap_page()
m_quickmap_in_use = false;
}
static inline bool is_user_address(VirtualAddress vaddr)
{
return vaddr.get() >= (8 * MB) && vaddr.get() < 0xc0000000;
}
bool MemoryManager::validate_user_stack(const Process& process, VirtualAddress vaddr) const
{
if (!is_user_address(vaddr))
return false;
auto* region = user_region_from_vaddr(const_cast<Process&>(process), vaddr);
return region && region->is_user_accessible() && region->is_stack();
}
bool MemoryManager::validate_user_read(const Process& process, VirtualAddress vaddr) const
{
if (!is_user_address(vaddr))
return false;
auto* region = user_region_from_vaddr(const_cast<Process&>(process), vaddr);
return region && region->is_user_accessible() && region->is_readable();
}
bool MemoryManager::validate_user_write(const Process& process, VirtualAddress vaddr) const
{
if (!is_user_address(vaddr))
return false;
auto* region = user_region_from_vaddr(const_cast<Process&>(process), vaddr);
return region && region->is_user_accessible() && region->is_writable();
}