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In HFS+ filesystems, during b-tree open (hfs_btree_open()), the code
verifies that the allocation map bit for the tree header (node 0) is
set. If not, it indicates a corrupted map record/bitmap and mounts
the volume as read-only (SB_RDONLY) to prevent further damage.
HFS filesystems share the same b-tree structure but currently lack
this corruption detection check.
Port this check to HFS, aligning its implementation with HFS+ to
maintain consistent b-tree logic across both filesystems:
1. Define struct hfs_bmap_ctx, and define HFS_TREE_HEAD and the relevant
map record indices in include/linux/hfs_common.h.
2. Port the necessary offset and length validation helpers to
fs/hfs/btree.h as static inline functions with robust null pointer
checks.
3. Implement static hfs_bmap_get_map_page() in fs/hfs/btree.c.
4. Implement static hfs_bmap_test_bit() in fs/hfs/btree.c to inspect
the B-tree bitmap using the get_map_page helper.
5. Implement static hfs_bmap_clear_bit() in fs/hfs/btree.c.
6. Rewrite hfs_bmap_alloc() in fs/hfs/btree.c to use the unified
hfs_bmap_get_map_page() helper, eliminating redundant page and offset
calculation code.
7. Refactor hfs_bmap_free() in fs/hfs/btree.c to use the new
hfs_bmap_clear_bit() helper.
8. In hfs_btree_open(), retrieve the header node via hfs_bnode_find(),
test its allocation bit with hfs_bmap_test_bit(), and release it
using hfs_bnode_put().
Suggested-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/all/6a36101b.be22b350.2a3e9.0001.GAE@google.com/T/#r446d0fed2a2900bd805534bbcb799d86619ae2ea
Signed-off-by: Aditya Prakash Srivastava <aditya.ansh182@gmail.com>
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/r/20260716074150.1660-1-aditya.ansh182@gmail.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
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Syzbot reported an uninit-value bug in [1] with a corrupted HFS+ image,
during the file system mounting process, specifically while loading the
catalog, a corrupted node_size value of 1 caused the rec_off argument
passed to hfs_bnode_read_u16() (within hfs_bnode_find()) to be excessively
large. Consequently, the function failed to return a valid value to
initialize the off variable, triggering the bug [1].
Every node starts from BTree node descriptor: struct hfs_bnode_desc.
So, the size of node cannot be lesser than that. However, technical
specification declares that: "The node size (which is expressed in bytes)
must be power of two, from 512 through 32,768, inclusive." Add a check
for btree node size base on technical specification.
[1]
BUG: KMSAN: uninit-value in hfsplus_bnode_find+0x141c/0x1600 fs/hfsplus/bnode.c:584
hfsplus_bnode_find+0x141c/0x1600 fs/hfsplus/bnode.c:584
hfsplus_btree_open+0x169a/0x1e40 fs/hfsplus/btree.c:382
hfsplus_fill_super+0x111f/0x2770 fs/hfsplus/super.c:553
get_tree_bdev_flags+0x6e6/0x920 fs/super.c:1694
get_tree_bdev+0x38/0x50 fs/super.c:1717
hfsplus_get_tree+0x35/0x40 fs/hfsplus/super.c:709
vfs_get_tree+0xb3/0x5d0 fs/super.c:1754
fc_mount fs/namespace.c:1193 [inline]
Fixes: 8ad2c6a36ac4 ("hfsplus: validate b-tree node 0 bitmap at mount time")
Reported-by: syzbot+217eb327242d08197efb@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=217eb327242d08197efb
Signed-off-by: Edward Adam Davis <eadavis@qq.com>
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/r/tencent_5ED373437A697F83A4A446B771577626CD05@qq.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
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In hfsplus_init_header_node() when node_count > 63488
(header bitmap capacity), the code calculates map_nodes,
subtracts them from free_nodes, and marks their positions
used in the bitmap. However, it doesn't write the actual
map node structure (type, record offsets, bitmap) for
those physical positions, only node 0 is written.
This patch reworks hfsplus_create_attributes_file()
logic by introducing a specialized method of
hfsplus_init_map_node() and writing the allocated
map b-tree's nodes by means of
hfsplus_write_attributes_file_node() method.
cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
cc: Yangtao Li <frank.li@vivo.com>
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/r/20260403230556.614171-5-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
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The xfstests' test-case generic/523 fails to execute
correctly:
FSTYP -- hfsplus
PLATFORM -- Linux/x86_64 hfsplus-testing-0001 6.15.0-rc4+ #8 SMP PREEMPT_DYNAMIC Thu May 1 16:43:22 PDT 2025
MKFS_OPTIONS -- /dev/loop51
MOUNT_OPTIONS -- /dev/loop51 /mnt/scratch
generic/523 - output mismatch (see xfstests-dev/results//generic/523.out.bad)
The test-case expects to have '/' in the xattr name.
However, HFS+ unicode logic makes conversion of '/'
into ':'. In HFS+, a filename can contain '/' because
':' is the separator. The slash is a valid filename
character on macOS. But on Linux, / is the path separator
and it cannot appear in a filename component. But xattr
name can contain any of these symbols. It means that
this unicode logic conversion doesn't need to be executed
for the case of xattr name.
This patch adds distinguishing the regular and xattr names.
If we have a regular name, then this conversion of special
symbols will be executed. Otherwise, the conversion is skipped
for the case of xattr names.
sudo ./check -g auto
FSTYP -- hfsplus
PLATFORM -- Linux/x86_64 hfsplus-testing-0001 7.0.0-rc1+ #24 SMP PREEMPT_DYNAMIC Fri Mar 20 12:36:49 PDT 2026
MKFS_OPTIONS -- /dev/loop51
MOUNT_OPTIONS -- /dev/loop51 /mnt/scratch
<skipped>
generic/523 33s ... 25s
<skipped>
Closes: https://github.com/hfs-linux-kernel/hfs-linux-kernel/issues/178
cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
cc: Yangtao Li <frank.li@vivo.com>
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/r/20260324003949.417048-2-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
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In HFS+ b-trees, the node allocation bitmap is stored across multiple
records. The first chunk resides in the b-tree Header Node at record
index 2, while all subsequent chunks are stored in dedicated Map Nodes
at record index 0.
This structural quirk forces callers like hfs_bmap_alloc() and
hfs_bmap_free() to duplicate boilerplate code to validate offsets, correct
lengths, and map the underlying pages via kmap_local_page(). There is
also currently no strict node-type validation before reading these
records, leaving the allocator vulnerable if a corrupted image points a
map linkage to an Index or Leaf node.
Introduce a unified bit-level API to encapsulate the map record access:
1. A new `struct hfs_bmap_ctx` to cleanly pass state and safely handle
page math across all architectures.
2. `hfs_bmap_get_map_page()`: Automatically validates node types
(HFS_NODE_HEADER vs HFS_NODE_MAP), infers the correct record index,
handles page-boundary math, and returns the unmapped `struct page *`
directly to the caller to avoid asymmetric mappings.
3. `hfs_bmap_clear_bit()`: A clean wrapper that internally handles page
mapping/unmapping for single-bit operations.
Refactor hfs_bmap_alloc() and hfs_bmap_free() to utilize this new API.
This deduplicates the allocator logic, hardens the map traversal against
fuzzed images, and provides the exact abstractions needed for upcoming
mount-time validation checks.
Signed-off-by: Shardul Bankar <shardul.b@mpiricsoftware.com>
Reviewed-by: Viacheslav Dubeyko <slava@dubeyko.com>
Tested-by: Viacheslav Dubeyko <slava@dubeyko.com>
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
Link: https://lore.kernel.org/r/20260318073823.3933718-2-shardul.b@mpiricsoftware.com
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
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Currently, HFS declares on-disk layout's metadata structures
in fs/hfs/hfs.h and HFS+ declares it in fs/hfsplus/hfsplus_raw.h.
However, HFS and HFS+ on-disk layouts have some similarity and
overlapping in declarations. As a result, fs/hfs/hfs.h and
fs/hfsplus/hfsplus_raw.h contain multiple duplicated declarations.
Moreover, both HFS and HFS+ drivers contain completely similar
implemented functionality in multiple places.
This patch is moving the on-disk layout declarations from
fs/hfs/hfs.h and fs/hfsplus/hfsplus_raw.h into
include/linux/hfs_common.h with the goal to exclude
the duplication in declarations. Also, this patch prepares
the basis for creating a hfslib that can aggregate common
functionality without necessity to duplicate the same code
in HFS and HFS+ drivers.
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
cc: Yangtao Li <frank.li@vivo.com>
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
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Currently, HFS/HFS+ has very obsolete and inconvenient
debug output subsystem. Also, the code is duplicated
in HFS and HFS+ driver. This patch introduces
linux/hfs_common.h for gathering common declarations,
inline functions, and common short methods. Currently,
this file contains only hfs_dbg() function that
employs pr_debug() with the goal to print a debug-level
messages conditionally.
So, now, it is possible to enable the debug output
by means of:
echo 'file extent.c +p' > /proc/dynamic_debug/control
echo 'func hfsplus_evict_inode +p' > /proc/dynamic_debug/control
And debug output looks like this:
hfs: pid 5831:fs/hfs/catalog.c:228 hfs_cat_delete(): delete_cat: 00,48
hfs: pid 5831:fs/hfs/extent.c:484 hfs_file_truncate(): truncate: 48, 409600 -> 0
hfs: pid 5831:fs/hfs/extent.c:212 hfs_dump_extent():
hfs: pid 5831:fs/hfs/extent.c:214 hfs_dump_extent(): 78:4
hfs: pid 5831:fs/hfs/extent.c:214 hfs_dump_extent(): 0:0
hfs: pid 5831:fs/hfs/extent.c:214 hfs_dump_extent(): 0:0
v4
Debug messages have been reworked and information about
new HFS/HFS+ shared declarations file has been added
to MAINTAINERS file.
v5
Yangtao Li suggested to clean up debug output and
fix several typos.
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
cc: Yangtao Li <frank.li@vivo.com>
cc: linux-fsdevel@vger.kernel.org
cc: Johannes Thumshirn <Johannes.Thumshirn@wdc.com>
Signed-off-by: Viacheslav Dubeyko <slava@dubeyko.com>
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