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Kernel: Allow file backed mapping be larger than inode size 

This is only allowed if the mapping does **not** exceed a page boundary.
Some port was doing an exactly two-page-mapping on a file that was one
and a half page long
This commit is contained in:
Bananymous 2025-08-26 17:42:48 +03:00
parent d9c91589f0
commit 706cfeb443
1 changed files with 6 additions and 1 deletions
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7
kernel/kernel/Memory/FileBackedRegion.cpp
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@ -13,7 +13,12 @@ namespace Kernel
if (offset < 0 || offset % PAGE_SIZE || size == 0)
return BAN::Error::from_errno(EINVAL);
if ((size > (size_t)inode->size() || (size_t)offset > (size_t)inode->size() - size))
size_t inode_size_aligned = inode->size();
if (auto rem = inode_size_aligned % PAGE_SIZE)
inode_size_aligned += PAGE_SIZE - rem;
if ((size > inode_size_aligned || static_cast<size_t>(offset) > inode_size_aligned - size))
return BAN::Error::from_errno(EOVERFLOW);
auto* region_ptr = new FileBackedRegion(inode, page_table, offset, size, type, flags, status_flags);