linux-stable.git/fs/hfs, branch linux-rolling-lts

hfs/hfsplus: fix u32 overflow in check_and_correct_requested_length

2026-07-24T14:17:23+00:00

[ Upstream commit 966cb76fb2857a4242cab6ea2ea17acf818a3da7 ]

check_and_correct_requested_length() compares (off + len) against
node_size using u32 arithmetic.  When the caller passes a large len
value (e.g. from an underflowed subtraction in hfs_brec_remove()),
off + len can wrap past 2^32 and produce a small result, causing the
bounds check to pass when it should fail.

For example, with off=14 and len=0xFFFFFFF2 (underflowed from
data_off - keyoffset - size in hfs_brec_remove), off + len wraps to 6,
which is less than a typical node_size of 512, so the check passes and
the subsequent memmove reads ~4GB past the node buffer.

Fix this by widening the addition to u64 before comparing against
node_size.  This prevents the u32 wrap while keeping the logic
straightforward.

Reported-by: syzbot+6df204b70bf3261691c5@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=6df204b70bf3261691c5
Tested-by: syzbot+6df204b70bf3261691c5@syzkaller.appspotmail.com
Reported-by: syzbot+e76bf3d19b85350571ac@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=e76bf3d19b85350571ac
Tested-by: syzbot+e76bf3d19b85350571ac@syzkaller.appspotmail.com
Fixes: a431930c9bac ("hfs: fix slab-out-of-bounds in hfs_bnode_read()")
Cc: stable@vger.kernel.org
Signed-off-by: Tristan Madani 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Viacheslav Dubeyko 
Link: https://lore.kernel.org/r/20260505111300.3592757-2-tristmd@gmail.com
Signed-off-by: Viacheslav Dubeyko 
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

hfs/hfsplus: prevent getting negative values of offset/length

2026-07-24T14:17:23+00:00

[ Upstream commit 00c14a09a70e10ae18eb3707d0059291425c04bd ]

The syzbot reported KASAN out-of-bounds issue in
hfs_bnode_move():

[   45.588165][ T9821] hfs: dst 14, src 65536, len -65536
[   45.588895][ T9821] ==================================================================
[   45.590114][ T9821] BUG: KASAN: out-of-bounds in hfs_bnode_move+0xfd/0x140
[   45.591127][ T9821] Read of size 18446744073709486080 at addr ffff888035935400 by task repro/9821
[   45.592207][ T9821]
[   45.592420][ T9821] CPU: 0 UID: 0 PID: 9821 Comm: repro Not tainted 6.16.0-rc7-dirty #42 PREEMPT(full)
[   45.592428][ T9821] Hardware name: QEMU Ubuntu 24.04 PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[   45.592431][ T9821] Call Trace:
[   45.592434][ T9821]  
[   45.592437][ T9821]  dump_stack_lvl+0x1c1/0x2a0
[   45.592446][ T9821]  ? __virt_addr_valid+0x1c8/0x5c0
[   45.592454][ T9821]  ? __pfx_dump_stack_lvl+0x10/0x10
[   45.592461][ T9821]  ? rcu_is_watching+0x15/0xb0
[   45.592469][ T9821]  ? lock_release+0x4b/0x3e0
[   45.592476][ T9821]  ? __virt_addr_valid+0x1c8/0x5c0
[   45.592483][ T9821]  ? __virt_addr_valid+0x4a5/0x5c0
[   45.592491][ T9821]  print_report+0x17e/0x7c0
[   45.592497][ T9821]  ? __virt_addr_valid+0x1c8/0x5c0
[   45.592504][ T9821]  ? __virt_addr_valid+0x4a5/0x5c0
[   45.592511][ T9821]  ? __phys_addr+0xd3/0x180
[   45.592519][ T9821]  ? hfs_bnode_move+0xfd/0x140
[   45.592526][ T9821]  kasan_report+0x147/0x180
[   45.592531][ T9821]  ? _printk+0xcf/0x120
[   45.592537][ T9821]  ? hfs_bnode_move+0xfd/0x140
[   45.592544][ T9821]  ? hfs_bnode_move+0xfd/0x140
[   45.592552][ T9821]  kasan_check_range+0x2b0/0x2c0
[   45.592557][ T9821]  ? hfs_bnode_move+0xfd/0x140
[   45.592565][ T9821]  __asan_memmove+0x29/0x70
[   45.592572][ T9821]  hfs_bnode_move+0xfd/0x140
[   45.592580][ T9821]  hfs_brec_remove+0x473/0x560
[   45.592589][ T9821]  hfs_cat_move+0x6fb/0x960
[   45.592598][ T9821]  ? __pfx_hfs_cat_move+0x10/0x10
[   45.592607][ T9821]  ? seqcount_lockdep_reader_access+0x122/0x1c0
[   45.592614][ T9821]  ? lockdep_hardirqs_on+0x9c/0x150
[   45.592631][ T9821]  ? __lock_acquire+0xaec/0xd80
[   45.592641][ T9821]  hfs_rename+0x1dc/0x2d0
[   45.592649][ T9821]  ? __pfx_hfs_rename+0x10/0x10
[   45.592657][ T9821]  vfs_rename+0xac6/0xed0
[   45.592664][ T9821]  ? __pfx_vfs_rename+0x10/0x10
[   45.592670][ T9821]  ? d_alloc+0x144/0x190
[   45.592677][ T9821]  ? bpf_lsm_path_rename+0x9/0x20
[   45.592683][ T9821]  ? security_path_rename+0x17d/0x490
[   45.592691][ T9821]  do_renameat2+0x890/0xc50
[   45.592699][ T9821]  ? __pfx_do_renameat2+0x10/0x10
[   45.592707][ T9821]  ? getname_flags+0x1e5/0x540
[   45.592714][ T9821]  __x64_sys_rename+0x82/0x90
[   45.592720][ T9821]  ? entry_SYSCALL_64_after_hwframe+0x77/0x7f
[   45.592725][ T9821]  do_syscall_64+0xf3/0x3a0
[   45.592741][ T9821]  ? exc_page_fault+0x9f/0xf0
[   45.592748][ T9821]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[   45.592754][ T9821] RIP: 0033:0x7f7f73fe3fc9
[   45.592760][ T9821] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 48
[   45.592765][ T9821] RSP: 002b:00007ffc7e116cf8 EFLAGS: 00000283 ORIG_RAX: 0000000000000052
[   45.592772][ T9821] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f7f73fe3fc9
[   45.592776][ T9821] RDX: 0000200000000871 RSI: 0000200000000780 RDI: 00002000000003c0
[   45.592781][ T9821] RBP: 00007ffc7e116d00 R08: 0000000000000000 R09: 00007ffc7e116d30
[   45.592784][ T9821] R10: fffffffffffffff0 R11: 0000000000000283 R12: 00005557e81f8250
[   45.592788][ T9821] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
[   45.592795][ T9821]  
[   45.592797][ T9821]
[   45.619721][ T9821] The buggy address belongs to the physical page:
[   45.620300][ T9821] page: refcount:1 mapcount:1 mapping:0000000000000000 index:0x559a88174 pfn:0x35935
[   45.621150][ T9821] memcg:ffff88810a1d5b00
[   45.621531][ T9821] anon flags: 0xfff60000020838(uptodate|dirty|lru|owner_2|swapbacked|node=0|zone=1|lastcpupid=0x7ff)
[   45.622496][ T9821] raw: 00fff60000020838 ffffea0000d64d88 ffff888021753e10 ffff888029da0771
[   45.623260][ T9821] raw: 0000000559a88174 0000000000000000 0000000100000000 ffff88810a1d5b00
[   45.624030][ T9821] page dumped because: kasan: bad access detected
[   45.624602][ T9821] page_owner tracks the page as allocated
[   45.625115][ T9821] page last allocated via order 0, migratetype Movable, gfp_mask 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO0
[   45.626685][ T9821]  post_alloc_hook+0x240/0x2a0
[   45.627127][ T9821]  get_page_from_freelist+0x2101/0x21e0
[   45.627628][ T9821]  __alloc_frozen_pages_noprof+0x274/0x380
[   45.628154][ T9821]  alloc_pages_mpol+0x241/0x4b0
[   45.628593][ T9821]  vma_alloc_folio_noprof+0xe4/0x210
[   45.629066][ T9821]  folio_prealloc+0x30/0x180
[   45.629487][ T9821]  __handle_mm_fault+0x34bd/0x5640
[   45.629957][ T9821]  handle_mm_fault+0x40e/0x8e0
[   45.630392][ T9821]  do_user_addr_fault+0xa81/0x1390
[   45.630862][ T9821]  exc_page_fault+0x76/0xf0
[   45.631273][ T9821]  asm_exc_page_fault+0x26/0x30
[   45.631712][ T9821] page last free pid 5269 tgid 5269 stack trace:
[   45.632281][ T9821]  free_unref_folios+0xc73/0x14c0
[   45.632740][ T9821]  folios_put_refs+0x55b/0x640
[   45.633177][ T9821]  free_pages_and_swap_cache+0x26d/0x510
[   45.633685][ T9821]  tlb_flush_mmu+0x3a0/0x680
[   45.634105][ T9821]  tlb_finish_mmu+0xd4/0x200
[   45.634525][ T9821]  exit_mmap+0x44c/0xb70
[   45.634914][ T9821]  __mmput+0x118/0x420
[   45.635286][ T9821]  exit_mm+0x1da/0x2c0
[   45.635659][ T9821]  do_exit+0x652/0x2330
[   45.636039][ T9821]  do_group_exit+0x21c/0x2d0
[   45.636457][ T9821]  __x64_sys_exit_group+0x3f/0x40
[   45.636915][ T9821]  x64_sys_call+0x21ba/0x21c0
[   45.637342][ T9821]  do_syscall_64+0xf3/0x3a0
[   45.637756][ T9821]  entry_SYSCALL_64_after_hwframe+0x77/0x7f
[   45.638290][ T9821] page has been migrated, last migrate reason: numa_misplaced
[   45.638956][ T9821]
[   45.639173][ T9821] Memory state around the buggy address:
[   45.639677][ T9821]  ffff888035935300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   45.640397][ T9821]  ffff888035935380: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   45.641117][ T9821] >ffff888035935400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   45.641837][ T9821]                    ^
[   45.642207][ T9821]  ffff888035935480: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   45.642929][ T9821]  ffff888035935500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   45.643650][ T9821] ==================================================================

This commit [1] fixes the issue if an offset inside of b-tree node
or length of the request is bigger than b-tree node. However,
this fix is still not ready for negative values
of the offset or length. Moreover, negative values of
the offset or length doesn't make sense for b-tree's
operations. Because we could try to access the memory address
outside of the beginning of memory page's addresses range.
Also, using of negative values make logic very complicated,
unpredictable, and we could access the wrong item(s)
in the b-tree node.

This patch changes b-tree interface by means of converting
signed integer arguments of offset and length on u32 type.
Such conversion has goal to prevent of using negative values
unintentionally or by mistake in b-tree operations.

[1] 'commit a431930c9bac ("hfs: fix slab-out-of-bounds in hfs_bnode_read()")'

Signed-off-by: Viacheslav Dubeyko 
cc: John Paul Adrian Glaubitz 
cc: Yangtao Li 
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20251002200020.2578311-1-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko 
Stable-dep-of: 966cb76fb285 ("hfs/hfsplus: fix u32 overflow in check_and_correct_requested_length")
Signed-off-by: Sasha Levin 
Signed-off-by: Greg Kroah-Hartman

hfs/hfsplus: zero-initialize buffer in hfs_bnode_read

2026-07-18T14:53:22+00:00

commit d67aadee19ffdf3cc8520c5a4f4d5b2916d30baf upstream.

hfs_bnode_read() can return early without writing to the output buffer
when is_bnode_offset_valid() fails or when check_and_correct_requested_
length() corrects the length to zero.  Callers such as hfs_bnode_read_
u16() and hfs_bnode_read_u8() pass stack-allocated buffers and use the
result unconditionally, leading to KMSAN uninit-value reports.

Rather than initializing at each individual call site, zero the buffer
at the start of hfs_bnode_read() before any validation checks.  This
ensures all callers in both hfs and hfsplus get a deterministic zero
value regardless of which early-return path is taken.

Reported-by: syzbot+217eb327242d08197efb@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=217eb327242d08197efb
Tested-by: syzbot+217eb327242d08197efb@syzkaller.appspotmail.com
Fixes: a431930c9bac ("hfs: fix slab-out-of-bounds in hfs_bnode_read()")
Cc: stable@vger.kernel.org
Signed-off-by: Tristan Madani 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Viacheslav Dubeyko 
Link: https://lore.kernel.org/r/20260505111300.3592757-3-tristmd@gmail.com
Signed-off-by: Viacheslav Dubeyko 
Signed-off-by: Greg Kroah-Hartman

hfs: ensure sb->s_fs_info is always cleaned up

2026-02-16T09:19:44+00:00

commit 05ce49a902be15dc93854cbfc20161205a9ee446 upstream.

When hfs was converted to the new mount api a bug was introduced by
changing the allocation pattern of sb->s_fs_info. If setup_bdev_super()
fails after a new superblock has been allocated by sget_fc(), but before
hfs_fill_super() takes ownership of the filesystem-specific s_fs_info
data it was leaked.

Fix this by freeing sb->s_fs_info in hfs_kill_super().

Cc: stable@vger.kernel.org
Fixes: ffcd06b6d13b ("hfs: convert hfs to use the new mount api")
Reported-by: syzbot+ad45f827c88778ff7df6@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=ad45f827c88778ff7df6
Tested-by: Viacheslav Dubeyko 
Signed-off-by: Christian Brauner 
Signed-off-by: Mehdi Ben Hadj Khelifa 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Viacheslav Dubeyko 
Link: https://lore.kernel.org/r/20251201222843.82310-2-mehdi.benhadjkhelifa@gmail.com
Signed-off-by: Viacheslav Dubeyko 
Signed-off-by: Greg Kroah-Hartman

hfs: fix potential use after free in hfs_correct_next_unused_CNID()

2025-12-18T13:02:52+00:00

[ Upstream commit c105e76bb17cf4b55fe89c6ad4f6a0e3972b5b08 ]

This code calls hfs_bnode_put(node) which drops the refcount and then
dreferences "node" on the next line.  It's only safe to use "node"
when we're holding a reference so flip these two lines around.

Fixes: a06ec283e125 ("hfs: add logic of correcting a next unused CNID")
Signed-off-by: Dan Carpenter 
Reviewed-by: Viacheslav Dubeyko 
Signed-off-by: Viacheslav Dubeyko 
Link: https://lore.kernel.org/r/aN-Xw8KnbSnuIcLk@stanley.mountain
Signed-off-by: Viacheslav Dubeyko 
Signed-off-by: Sasha Levin

hfs/hfsplus: rework debug output subsystem

2025-09-24T23:30:34+00:00

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 
cc: John Paul Adrian Glaubitz 
cc: Yangtao Li 
cc: linux-fsdevel@vger.kernel.org
cc: Johannes Thumshirn 
Signed-off-by: Viacheslav Dubeyko

hfs: clear offset and space out of valid records in b-tree node

2025-09-01T01:16:00+00:00

Currently, hfs_brec_remove() executes moving records
towards the location of deleted record and it updates
offsets of moved records. However, the hfs_brec_remove()
logic ignores the "mess" of b-tree node's free space and
it doesn't touch the offsets out of records number.
Potentially, it could confuse fsck or driver logic or
to be a reason of potential corruption cases.

This patch reworks the logic of hfs_brec_remove()
by means of clearing freed space of b-tree node
after the records moving. And it clear the last
offset that keeping old location of free space
because now the offset before this one is keeping
the actual offset to the free space after the record
deletion.

Signed-off-by: Viacheslav Dubeyko 
cc: John Paul Adrian Glaubitz 
cc: Yangtao Li 
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20250815194918.38165-1-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko

hfs: add logic of correcting a next unused CNID

2025-09-01T01:15:21+00:00

The generic/736 xfstest fails for HFS case:

BEGIN TEST default (1 test): hfs Mon May 5 03:18:32 UTC 2025
DEVICE: /dev/vdb
HFS_MKFS_OPTIONS:
MOUNT_OPTIONS: MOUNT_OPTIONS
FSTYP -- hfs
PLATFORM -- Linux/x86_64 kvm-xfstests 6.15.0-rc4-xfstests-g00b827f0cffa #1 SMP PREEMPT_DYNAMIC Fri May 25
MKFS_OPTIONS -- /dev/vdc
MOUNT_OPTIONS -- /dev/vdc /vdc

generic/736 [03:18:33][ 3.510255] run fstests generic/736 at 2025-05-05 03:18:33
_check_generic_filesystem: filesystem on /dev/vdb is inconsistent
(see /results/hfs/results-default/generic/736.full for details)
Ran: generic/736
Failures: generic/736
Failed 1 of 1 tests

The HFS volume becomes corrupted after the test run:

sudo fsck.hfs -d /dev/loop50
** /dev/loop50
Using cacheBlockSize=32K cacheTotalBlock=1024 cacheSize=32768K.
Executing fsck_hfs (version 540.1-Linux).
** Checking HFS volume.
The volume name is untitled
** Checking extents overflow file.
** Checking catalog file.
** Checking catalog hierarchy.
** Checking volume bitmap.
** Checking volume information.
invalid MDB drNxtCNID
Master Directory Block needs minor repair
(1, 0)
Verify Status: VIStat = 0x8000, ABTStat = 0x0000 EBTStat = 0x0000
CBTStat = 0x0000 CatStat = 0x00000000
** Repairing volume.
** Rechecking volume.
** Checking HFS volume.
The volume name is untitled
** Checking extents overflow file.
** Checking catalog file.
** Checking catalog hierarchy.
** Checking volume bitmap.
** Checking volume information.
** The volume untitled was repaired successfully.

The main reason of the issue is the absence of logic that
corrects mdb->drNxtCNID/HFS_SB(sb)->next_id (next unused
CNID) after deleting a record in Catalog File. This patch
introduces a hfs_correct_next_unused_CNID() method that
implements the necessary logic. In the case of Catalog File's
record delete operation, the function logic checks that
(deleted_CNID + 1) == next_unused_CNID and it finds/sets the new
value of next_unused_CNID.

sudo ./check generic/736
FSTYP -- hfs
PLATFORM -- Linux/x86_64 hfsplus-testing-0001 6.15.0+ #6 SMP PREEMPT_DYNAMIC Tue Jun 10 15:02:48 PDT 2025
MKFS_OPTIONS -- /dev/loop51
MOUNT_OPTIONS -- /dev/loop51 /mnt/scratch

generic/736 33s
Ran: generic/736
Passed all 1 tests

sudo fsck.hfs -d /dev/loop50
** /dev/loop50
Using cacheBlockSize=32K cacheTotalBlock=1024 cacheSize=32768K.
Executing fsck_hfs (version 540.1-Linux).
** Checking HFS volume.
The volume name is untitled
** Checking extents overflow file.
** Checking catalog file.
** Checking catalog hierarchy.
** Checking volume bitmap.
** Checking volume information.
** The volume untitled appears to be OK

Signed-off-by: Viacheslav Dubeyko 
Link: https://lore.kernel.org/r/20250610231609.551930-1-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko

hfs: fix KMSAN uninit-value issue in hfs_find_set_zero_bits()

2025-09-01T01:13:10+00:00

The syzbot reported issue in hfs_find_set_zero_bits():

=====================================================
BUG: KMSAN: uninit-value in hfs_find_set_zero_bits+0x74d/0xb60 fs/hfs/bitmap.c:45
 hfs_find_set_zero_bits+0x74d/0xb60 fs/hfs/bitmap.c:45
 hfs_vbm_search_free+0x13c/0x5b0 fs/hfs/bitmap.c:151
 hfs_extend_file+0x6a5/0x1b00 fs/hfs/extent.c:408
 hfs_get_block+0x435/0x1150 fs/hfs/extent.c:353
 __block_write_begin_int+0xa76/0x3030 fs/buffer.c:2151
 block_write_begin fs/buffer.c:2262 [inline]
 cont_write_begin+0x10e1/0x1bc0 fs/buffer.c:2601
 hfs_write_begin+0x85/0x130 fs/hfs/inode.c:52
 cont_expand_zero fs/buffer.c:2528 [inline]
 cont_write_begin+0x35a/0x1bc0 fs/buffer.c:2591
 hfs_write_begin+0x85/0x130 fs/hfs/inode.c:52
 hfs_file_truncate+0x1d6/0xe60 fs/hfs/extent.c:494
 hfs_inode_setattr+0x964/0xaa0 fs/hfs/inode.c:654
 notify_change+0x1993/0x1aa0 fs/attr.c:552
 do_truncate+0x28f/0x310 fs/open.c:68
 do_ftruncate+0x698/0x730 fs/open.c:195
 do_sys_ftruncate fs/open.c:210 [inline]
 __do_sys_ftruncate fs/open.c:215 [inline]
 __se_sys_ftruncate fs/open.c:213 [inline]
 __x64_sys_ftruncate+0x11b/0x250 fs/open.c:213
 x64_sys_call+0xfe3/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:78
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4154 [inline]
 slab_alloc_node mm/slub.c:4197 [inline]
 __kmalloc_cache_noprof+0x7f7/0xed0 mm/slub.c:4354
 kmalloc_noprof include/linux/slab.h:905 [inline]
 hfs_mdb_get+0x1cc8/0x2a90 fs/hfs/mdb.c:175
 hfs_fill_super+0x3d0/0xb80 fs/hfs/super.c:337
 get_tree_bdev_flags+0x6e3/0x920 fs/super.c:1681
 get_tree_bdev+0x38/0x50 fs/super.c:1704
 hfs_get_tree+0x35/0x40 fs/hfs/super.c:388
 vfs_get_tree+0xb0/0x5c0 fs/super.c:1804
 do_new_mount+0x738/0x1610 fs/namespace.c:3902
 path_mount+0x6db/0x1e90 fs/namespace.c:4226
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x6eb/0x7d0 fs/namespace.c:4427
 __x64_sys_mount+0xe4/0x150 fs/namespace.c:4427
 x64_sys_call+0xfa7/0x3db0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 12609 Comm: syz.1.2692 Not tainted 6.16.0-syzkaller #0 PREEMPT(none)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
=====================================================

The HFS_SB(sb)->bitmap buffer is allocated in hfs_mdb_get():

HFS_SB(sb)->bitmap = kmalloc(8192, GFP_KERNEL);

Finally, it can trigger the reported issue because kmalloc()
doesn't clear the allocated memory. If allocated memory contains
only zeros, then everything will work pretty fine.
But if the allocated memory contains the "garbage", then
it can affect the bitmap operations and it triggers
the reported issue.

This patch simply exchanges the kmalloc() on kzalloc()
with the goal to guarantee the correctness of bitmap operations.
Because, newly created allocation bitmap should have all
available blocks free. Potentially, initialization bitmap's read
operation could not fill the whole allocated memory and
"garbage" in the not initialized memory will be the reason of
volume coruptions and file system driver bugs.

Reported-by: syzbot 
Closes: https://syzkaller.appspot.com/bug?extid=773fa9d79b29bd8b6831
Signed-off-by: Viacheslav Dubeyko 
cc: John Paul Adrian Glaubitz 
cc: Yangtao Li 
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20250820230636.179085-1-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko

hfs: make proper initalization of struct hfs_find_data

2025-09-01T01:11:55+00:00

Potenatially, __hfs_ext_read_extent() could operate by
not initialized values of fd->key after hfs_brec_find() call:

static inline int __hfs_ext_read_extent(struct hfs_find_data *fd, struct hfs_extent *extent,
                                        u32 cnid, u32 block, u8 type)
{
        int res;

        hfs_ext_build_key(fd->search_key, cnid, block, type);
        fd->key->ext.FNum = 0;
        res = hfs_brec_find(fd);
        if (res && res != -ENOENT)
                return res;
        if (fd->key->ext.FNum != fd->search_key->ext.FNum ||
            fd->key->ext.FkType != fd->search_key->ext.FkType)
                return -ENOENT;
        if (fd->entrylength != sizeof(hfs_extent_rec))
                return -EIO;
        hfs_bnode_read(fd->bnode, extent, fd->entryoffset, sizeof(hfs_extent_rec));
        return 0;
}

This patch changes kmalloc() on kzalloc() in hfs_find_init()
and intializes fd->record, fd->keyoffset, fd->keylength,
fd->entryoffset, fd->entrylength for the case if hfs_brec_find()
has been found nothing in the b-tree node.

Signed-off-by: Viacheslav Dubeyko 
cc: John Paul Adrian Glaubitz 
cc: Yangtao Li 
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/20250818225252.126427-1-slava@dubeyko.com
Signed-off-by: Viacheslav Dubeyko