linux-stable.git/fs/ext2/inode.c, branch linux-6.6.y

ext2: reject inodes with zero i_nlink and valid mode in ext2_iget()

2026-05-17T15:13:28+00:00

commit 25947cc5b2374cd5bf627fe3141496444260d04f upstream.

ext2_iget() already rejects inodes with i_nlink == 0 when i_mode is
zero or i_dtime is set, treating them as deleted. However, the case of
i_nlink == 0 with a non-zero mode and zero dtime slips through. Since
ext2 has no orphan list, such a combination can only result from
filesystem corruption - a legitimate inode deletion always sets either
i_dtime or clears i_mode before freeing the inode.

A crafted image can exploit this gap to present such an inode to the
VFS, which then triggers WARN_ON inside drop_nlink() (fs/inode.c) via
ext2_unlink(), ext2_rename() and ext2_rmdir():

WARNING: CPU: 3 PID: 609 at fs/inode.c:336 drop_nlink+0xad/0xd0 fs/inode.c:336
CPU: 3 UID: 0 PID: 609 Comm: syz-executor Not tainted 6.12.77+ #1
Call Trace:
 
 inode_dec_link_count include/linux/fs.h:2518 [inline]
 ext2_unlink+0x26c/0x300 fs/ext2/namei.c:295
 vfs_unlink+0x2fc/0x9b0 fs/namei.c:4477
 do_unlinkat+0x53e/0x730 fs/namei.c:4541
 __x64_sys_unlink+0xc6/0x110 fs/namei.c:4587
 do_syscall_64+0xf5/0x220 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
 

WARNING: CPU: 0 PID: 646 at fs/inode.c:336 drop_nlink+0xad/0xd0 fs/inode.c:336
CPU: 0 UID: 0 PID: 646 Comm: syz.0.17 Not tainted 6.12.77+ #1
Call Trace:
 
 inode_dec_link_count include/linux/fs.h:2518 [inline]
 ext2_rename+0x35e/0x850 fs/ext2/namei.c:374
 vfs_rename+0xf2f/0x2060 fs/namei.c:5021
 do_renameat2+0xbe2/0xd50 fs/namei.c:5178
 __x64_sys_rename+0x7e/0xa0 fs/namei.c:5223
 do_syscall_64+0xf5/0x220 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
 

WARNING: CPU: 0 PID: 634 at fs/inode.c:336 drop_nlink+0xad/0xd0 fs/inode.c:336
CPU: 0 UID: 0 PID: 634 Comm: syz-executor Not tainted 6.12.77+ #1
Call Trace:
 
 inode_dec_link_count include/linux/fs.h:2518 [inline]
 ext2_rmdir+0xca/0x110 fs/ext2/namei.c:311
 vfs_rmdir+0x204/0x690 fs/namei.c:4348
 do_rmdir+0x372/0x3e0 fs/namei.c:4407
 __x64_sys_unlinkat+0xf0/0x130 fs/namei.c:4577
 do_syscall_64+0xf5/0x220 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
 

Extend the existing i_nlink == 0 check to also catch this case,
reporting the corruption via ext2_error() and returning -EFSCORRUPTED.
This rejects the inode at load time and prevents it from reaching any
of the namei.c paths.

Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Signed-off-by: Vasiliy Kovalev 
Link: https://patch.msgid.link/20260404152011.2590197-1-kovalev@altlinux.org
Signed-off-by: Jan Kara 
Signed-off-by: Greg Kroah-Hartman

ext2: Handle fiemap on empty files to prevent EINVAL

2025-08-28T14:28:15+00:00

[ Upstream commit a099b09a3342a0b28ea330e405501b5b4d0424b4 ]

Previously, ext2_fiemap would unconditionally apply "len = min_t(u64, len,
i_size_read(inode));", When inode->i_size was 0 (for an empty file), this
would reduce the requested len to 0. Passing len = 0 to iomap_fiemap could
then result in an -EINVAL error, even for valid queries on empty files.

Link: https://github.com/linux-test-project/ltp/issues/1246
Signed-off-by: Wei Gao 
Signed-off-by: Jan Kara 
Link: https://patch.msgid.link/20250613152402.3432135-1-wegao@suse.com
Signed-off-by: Sasha Levin

Merge tag 'for_v6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs

2023-08-30T19:10:50+00:00

Pull ext2, quota, and udf updates from Jan Kara:

 - fixes for possible use-after-free issues with quota when racing with
   chown

 - fixes for ext2 crashing when xattr allocation races with another
   block allocation to the same file from page writeback code

 - fix for block number overflow in ext2

 - marking of reiserfs as obsolete in MAINTAINERS

 - assorted minor cleanups

* tag 'for_v6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
  ext2: Fix kernel-doc warnings
  ext2: improve consistency of ext2_fsblk_t datatype usage
  ext2: dump current reservation window info
  ext2: fix race between setxattr and write back
  ext2: introduce new flags argument for ext2_new_blocks()
  ext2: remove ext2_new_block()
  ext2: fix datatype of block number in ext2_xattr_set2()
  udf: Drop pointless aops assignment
  quota: use lockdep_assert_held_write in dquot_load_quota_sb
  MAINTAINERS: change reiserfs status to obsolete
  udf: Fix -Wstringop-overflow warnings
  quota: simplify drop_dquot_ref()
  quota: fix dqput() to follow the guarantees dquot_srcu should provide
  quota: add new helper dquot_active()
  quota: rename dquot_active() to inode_quota_active()
  quota: factor out dquot_write_dquot()
  ext2: remove redundant assignment to variable desc and variable best_desc

ext2: Fix kernel-doc warnings

2023-08-21T16:56:50+00:00

Document a few parameters of ext2_alloc_blocks().  Redo the
alloc_new_reservation() and find_next_reservable_window() kernel-doc
entirely.

Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Jan Kara 
Message-Id: <20230818201121.2720451-1-willy@infradead.org>

ext2: improve consistency of ext2_fsblk_t datatype usage

2023-08-18T10:54:54+00:00

The ext2 block allocation/deallocation functions and their respective
calls use a mixture of unsigned long and ext2_fsblk_t datatypes to
index the desired ext2 block. This commit replaces occurrences of
unsigned long with ext2_fsblk_t, covering the functions
ext2_new_block(), ext2_new_blocks(), ext2_free_blocks(),
ext2_free_data() and ext2_free_branches(). This commit is rather
conservative, and only replaces unsigned long with ext2_fsblk_t if
the variable is used to index a specific ext2 block.

Signed-off-by: Georg Ottinger 
Signed-off-by: Jan Kara 
Message-Id: <20230817195925.10268-1-g.ottinger@gmx.at>

ext2: introduce new flags argument for ext2_new_blocks()

2023-08-16T15:42:42+00:00

This patch introduces a new flags argument for ext2_new_blocks() and also
a new EXT2_ALLOC_NORESERVE flag.

Signed-off-by: Ye Bin 
Message-Id: <20230815112612.221145-3-yebin10@huawei.com>
Signed-off-by: Jan Kara

fs: pass the request_mask to generic_fillattr

2023-08-09T06:56:36+00:00

generic_fillattr just fills in the entire stat struct indiscriminately
today, copying data from the inode. There is at least one attribute
(STATX_CHANGE_COOKIE) that can have side effects when it is reported,
and we're looking at adding more with the addition of multigrain
timestamps.

Add a request_mask argument to generic_fillattr and have most callers
just pass in the value that is passed to getattr. Have other callers
(e.g. ksmbd) just pass in STATX_BASIC_STATS. Also move the setting of
STATX_CHANGE_COOKIE into generic_fillattr.

Acked-by: Joseph Qi 
Reviewed-by: Xiubo Li 
Reviewed-by: "Paulo Alcantara (SUSE)" 
Reviewed-by: Jan Kara 
Signed-off-by: Jeff Layton 
Message-Id: <20230807-mgctime-v7-2-d1dec143a704@kernel.org>
Signed-off-by: Christian Brauner

ext2: convert to ctime accessor functions

2023-07-13T08:28:07+00:00

In later patches, we're going to change how the inode's ctime field is
used. Switch to using accessor functions instead of raw accesses of
inode->i_ctime.

Signed-off-by: Jeff Layton 
Reviewed-by: Jan Kara 
Message-Id: <20230705190309.579783-39-jlayton@kernel.org>
Signed-off-by: Christian Brauner

ext2: Move direct-io to use iomap

2023-05-16T09:32:42+00:00

This patch converts ext2 direct-io path to iomap interface.
- This also takes care of DIO_SKIP_HOLES part in which we return -ENOTBLK
  from ext2_iomap_begin(), in case if the write is done on a hole.
- This fallbacks to buffered-io in case of DIO_SKIP_HOLES or in case of
  a partial write or if any error is detected in ext2_iomap_end().
  We try to return -ENOTBLK in such cases.
- For any unaligned or extending DIO writes, we pass
  IOMAP_DIO_FORCE_WAIT flag to ensure synchronous writes.
- For extending writes we set IOMAP_F_DIRTY in ext2_iomap_begin because
  otherwise with dsync writes on devices that support FUA, generic_write_sync
  won't be called and we might miss inode metadata updates.
- Since ext2 already now uses _nolock vartiant of sync write. Hence
  there is no inode lock problem with iomap in this patch.
- ext2_iomap_ops are now being shared by DIO, DAX & fiemap path

Tested-by: Disha Goel 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Ritesh Harjani (IBM) 
Signed-off-by: Jan Kara 
Message-Id: <610b672a52f2a7ff6dc550fd14d0f995806232a5.1682069716.git.ritesh.list@gmail.com>

ext2/dax: Fix ext2_setsize when len is page aligned

2023-05-16T09:32:42+00:00

PAGE_ALIGN(x) macro gives the next highest value which is multiple of
pagesize. But if x is already page aligned then it simply returns x.
So, if x passed is 0 in dax_zero_range() function, that means the
length gets passed as 0 to ->iomap_begin().

In ext2 it then calls ext2_get_blocks -> max_blocks as 0 and hits bug_on
here in ext2_get_blocks().
	BUG_ON(maxblocks == 0);

Instead we should be calling dax_truncate_page() here which takes
care of it. i.e. it only calls dax_zero_range if the offset is not
page/block aligned.

This can be easily triggered with following on fsdax mounted pmem
device.

dd if=/dev/zero of=file count=1 bs=512
truncate -s 0 file

[79.525838] EXT2-fs (pmem0): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
[79.529376] ext2 filesystem being mounted at /mnt1/test supports timestamps until 2038 (0x7fffffff)
[93.793207] ------------[ cut here ]------------
[93.795102] kernel BUG at fs/ext2/inode.c:637!
[93.796904] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[93.798659] CPU: 0 PID: 1192 Comm: truncate Not tainted 6.3.0-rc2-xfstests-00056-g131086faa369 #139
[93.806459] RIP: 0010:ext2_get_blocks.constprop.0+0x524/0x610
<...>
[93.835298] Call Trace:
[93.836253]  
[93.837103]  ? lock_acquire+0xf8/0x110
[93.838479]  ? d_lookup+0x69/0xd0
[93.839779]  ext2_iomap_begin+0xa7/0x1c0
[93.841154]  iomap_iter+0xc7/0x150
[93.842425]  dax_zero_range+0x6e/0xa0
[93.843813]  ext2_setsize+0x176/0x1b0
[93.845164]  ext2_setattr+0x151/0x200
[93.846467]  notify_change+0x341/0x4e0
[93.847805]  ? lock_acquire+0xf8/0x110
[93.849143]  ? do_truncate+0x74/0xe0
[93.850452]  ? do_truncate+0x84/0xe0
[93.851739]  do_truncate+0x84/0xe0
[93.852974]  do_sys_ftruncate+0x2b4/0x2f0
[93.854404]  do_syscall_64+0x3f/0x90
[93.855789]  entry_SYSCALL_64_after_hwframe+0x72/0xdc

CC: stable@vger.kernel.org
Fixes: 2aa3048e03d3 ("iomap: switch iomap_zero_range to use iomap_iter")
Reviewed-by: Darrick J. Wong 
Signed-off-by: Ritesh Harjani (IBM) 
Signed-off-by: Jan Kara 
Message-Id: <046a58317f29d9603d1068b2bbae47c2332c17ae.1682069716.git.ritesh.list@gmail.com>