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Kernel: Initialize DiskCache's buffer before the dirty&clean lists

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This commit fixes a kernel panic that happened when unmounting
a disk due to an invalid memory access.
This was because `DiskCache` initializes two linked lists that use
an argument `KBuffer` as the storage for their elements.
Since the member `KBuffer` was declared after the two lists,
when `DiskCache`'s destructor was called, then `KBuffer`'s destructor
was called before the ones of the two lists, causing a page fault in
the kernel.
This commit is contained in:
Marco Cutecchia 2023-04-01 19:11:21 +02:00 • committed by Andrew Kaster
parent 7375beced3
commit 1b04c43690
1 changed files with 5 additions and 2 deletions
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7
Kernel/FileSystem/BlockBasedFileSystem.cpp
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@ -101,11 +101,14 @@ public:
private: private:
mutable NonnullRefPtr<BlockBasedFileSystem> m_fs; mutable NonnullRefPtr<BlockBasedFileSystem> m_fs;
NonnullOwnPtr<KBuffer> m_cached_block_data;
// NOTE: m_entries must be declared before m_dirty_list and m_clean_list because their entries are allocated from it.
// We need to ensure that the destructors of m_dirty_list and m_clean_list are called before m_entries is destroyed.
NonnullOwnPtr<KBuffer> m_entries;
mutable IntrusiveList<&CacheEntry::list_node> m_dirty_list; mutable IntrusiveList<&CacheEntry::list_node> m_dirty_list;
mutable IntrusiveList<&CacheEntry::list_node> m_clean_list; mutable IntrusiveList<&CacheEntry::list_node> m_clean_list;
mutable HashMap<BlockBasedFileSystem::BlockIndex, CacheEntry*> m_hash; mutable HashMap<BlockBasedFileSystem::BlockIndex, CacheEntry*> m_hash;
NonnullOwnPtr<KBuffer> m_cached_block_data;
NonnullOwnPtr<KBuffer> m_entries;
}; };
BlockBasedFileSystem::BlockBasedFileSystem(OpenFileDescription& file_description) BlockBasedFileSystem::BlockBasedFileSystem(OpenFileDescription& file_description)