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Kernel: Fix off-by-one in Memory::is_user_range() check

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This function was checking 1 byte after the provided range, which caused
it to reject valid userspace ranges that happened to end exactly at the
top of the user address space.

This fixes a long-standing issue with mysterious Optional errors in
Coredump::write_regions(). (It happened when trying to add a memory
region at the very top of the address space to a coredump.)
This commit is contained in:
Andreas Kling 2021-09-11 02:34:55 +02:00
parent 2116fb5be9
commit 890c647e0f
1 changed files with 5 additions and 1 deletions
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6
Kernel/Memory/MemoryManager.h
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@ -302,7 +302,11 @@ inline bool is_user_range(VirtualAddress vaddr, size_t size)
{ {
if (vaddr.offset(size) < vaddr) if (vaddr.offset(size) < vaddr)
return false; return false;
return is_user_address(vaddr) && is_user_address(vaddr.offset(size)); if (!is_user_address(vaddr))
return false;
if (size <= 1)
return true;
return is_user_address(vaddr.offset(size - 1));
} }
inline bool is_user_range(VirtualRange const& range) inline bool is_user_range(VirtualRange const& range)