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Linux kernel
============
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the problems which may result by upgrading your kernel.
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Mounting a corrupted filesystem with directory which contains '.' dir
entry with rec_len == block size results in out-of-bounds read (later
on, when the corrupted directory is removed).
ext4_empty_dir() assumes every ext4 directory contains at least '.'
and '..' as directory entries in the first data block. It first loads
the '.' dir entry, performs sanity checks by calling ext4_check_dir_entry()
and then uses its rec_len member to compute the location of '..' dir
entry (in ext4_next_entry). It assumes the '..' dir entry fits into the
same data block.
If the rec_len of '.' is precisely one block (4KB), it slips through the
sanity checks (it is considered the last directory entry in the data
block) and leaves "struct ext4_dir_entry_2 *de" point exactly past the
memory slot allocated to the data block. The following call to
ext4_check_dir_entry() on new value of de then dereferences this pointer
which results in out-of-bounds mem access.
Fix this by extending __ext4_check_dir_entry() to check for '.' dir
entries that reach the end of data block. Make sure to ignore the phony
dir entries for checksum (by checking name_len for non-zero).
Note: This is reported by KASAN as use-after-free in case another
structure was recently freed from the slot past the bound, but it is
really an OOB read.
This issue was found by syzkaller tool.
Call Trace:
[ 38.594108] BUG: KASAN: slab-use-after-free in __ext4_check_dir_entry+0x67e/0x710
[ 38.594649] Read of size 2 at addr ffff88802b41a004 by task syz-executor/5375
[ 38.595158]
[ 38.595288] CPU: 0 UID: 0 PID: 5375 Comm: syz-executor Not tainted 6.14.0-rc7 #1
[ 38.595298] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
[ 38.595304] Call Trace:
[ 38.595308] <TASK>
[ 38.595311] dump_stack_lvl+0xa7/0xd0
[ 38.595325] print_address_description.constprop.0+0x2c/0x3f0
[ 38.595339] ? __ext4_check_dir_entry+0x67e/0x710
[ 38.595349] print_report+0xaa/0x250
[ 38.595359] ? __ext4_check_dir_entry+0x67e/0x710
[ 38.595368] ? kasan_addr_to_slab+0x9/0x90
[ 38.595378] kasan_report+0xab/0xe0
[ 38.595389] ? __ext4_check_dir_entry+0x67e/0x710
[ 38.595400] __ext4_check_dir_entry+0x67e/0x710
[ 38.595410] ext4_empty_dir+0x465/0x990
[ 38.595421] ? __pfx_ext4_empty_dir+0x10/0x10
[ 38.595432] ext4_rmdir.part.0+0x29a/0xd10
[ 38.595441] ? __dquot_initialize+0x2a7/0xbf0
[ 38.595455] ? __pfx_ext4_rmdir.part.0+0x10/0x10
[ 38.595464] ? __pfx___dquot_initialize+0x10/0x10
[ 38.595478] ? down_write+0xdb/0x140
[ 38.595487] ? __pfx_down_write+0x10/0x10
[ 38.595497] ext4_rmdir+0xee/0x140
[ 38.595506] vfs_rmdir+0x209/0x670
[ 38.595517] ? lookup_one_qstr_excl+0x3b/0x190
[ 38.595529] do_rmdir+0x363/0x3c0
[ 38.595537] ? __pfx_do_rmdir+0x10/0x10
[ 38.595544] ? strncpy_from_user+0x1ff/0x2e0
[ 38.595561] __x64_sys_unlinkat+0xf0/0x130
[ 38.595570] do_syscall_64+0x5b/0x180
[ 38.595583] entry_SYSCALL_64_after_hwframe+0x76/0x7e
Fixes: ac27a0ec112a0 ("[PATCH] ext4: initial copy of files from ext3")
Signed-off-by: Jakub Acs <acsjakub@amazon.de>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: linux-ext4@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: Mahmoud Adam <mngyadam@amazon.com>
Cc: stable@vger.kernel.org
Cc: security@kernel.org
Link: https://patch.msgid.link/b3ae36a6794c4a01944c7d70b403db5b@amazon.de
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
A user complained that a message such as:
EXT4-fs (nvme0n1p3): re-mounted UUID ro. Quota mode: none.
implied that the file system was previously mounted read/write and was
now remounted read-only, when it could have been some other mount
state that had changed by the "mount -o remount" operation. Fix this
by only logging "ro"or "r/w" when it has changed.
https://bugzilla.kernel.org/show_bug.cgi?id=219132
Signed-off-by: Nicolas Bretz <bretznic@gmail.com>
Link: https://patch.msgid.link/20250319171011.8372-1-bretznic@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
The error out label of file_modified() should be out_inode_lock in
ext4_fallocate().
Fixes: 2890e5e0f49e ("ext4: move out common parts into ext4_fallocate()")
Reported-by: Baokun Li <libaokun1@huawei.com>
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Link: https://patch.msgid.link/20250319023557.2785018-1-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Currently, outside error paths, we auto commit the super block after 1
hour has passed and 16MB worth of updates have been written since last
commit. This is a policy decision so make this tunable while keeping the
defaults same. This is useful if user wants to tweak the superblock
behavior or for debugging the codepath by allowing to trigger it more
frequently.
We can now tweak the super block update using sb_update_sec and
sb_update_kb files in /sys/fs/ext4/<dev>/
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/950fb8c9b2905620e16f02a3b9eeea5a5b6cb87e.1742279837.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Presently we always BUG_ON if trying to start a transaction on a journal marked
with JBD2_UNMOUNT, since this should never happen. However, while ltp running
stress tests, it was observed that in case of some error handling paths, it is
possible for update_super_work to start a transaction after the journal is
destroyed eg:
(umount)
ext4_kill_sb
kill_block_super
generic_shutdown_super
sync_filesystem /* commits all txns */
evict_inodes
/* might start a new txn */
ext4_put_super
flush_work(&sbi->s_sb_upd_work) /* flush the workqueue */
jbd2_journal_destroy
journal_kill_thread
journal->j_flags |= JBD2_UNMOUNT;
jbd2_journal_commit_transaction
jbd2_journal_get_descriptor_buffer
jbd2_journal_bmap
ext4_journal_bmap
ext4_map_blocks
...
ext4_inode_error
ext4_handle_error
schedule_work(&sbi->s_sb_upd_work)
/* work queue kicks in */
update_super_work
jbd2_journal_start
start_this_handle
BUG_ON(journal->j_flags &
JBD2_UNMOUNT)
Hence, introduce a new mount flag to indicate journal is destroying and only do
a journaled (and deferred) update of sb if this flag is not set. Otherwise, just
fallback to an un-journaled commit.
Further, in the journal destroy path, we have the following sequence:
1. Set mount flag indicating journal is destroying
2. force a commit and wait for it
3. flush pending sb updates
This sequence is important as it ensures that, after this point, there is no sb
update that might be journaled so it is safe to update the sb outside the
journal. (To avoid race discussed in 2d01ddc86606)
Also, we don't need a similar check in ext4_grp_locked_error since it is only
called from mballoc and AFAICT it would be always valid to schedule work here.
Fixes: 2d01ddc86606 ("ext4: save error info to sb through journal if available")
Reported-by: Mahesh Kumar <maheshkumar657g@gmail.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/9613c465d6ff00cd315602f99283d5f24018c3f7.1742279837.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Define an ext4 wrapper over jbd2_journal_destroy to make sure we
have consistent behavior during journal destruction. This will also
come useful in the next patch where we add some ext4 specific logic
in the destroy path.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Signed-off-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Link: https://patch.msgid.link/c3ba78c5c419757e6d5f2d8ebb4a8ce9d21da86a.1742279837.git.ojaswin@linux.ibm.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
sizeof(char) evaluates to 1. Remove the churn.
Signed-off-by: Ethan Carter Edwards <ethan@ethancedwards.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Link: https://patch.msgid.link/20250316-ext4-hash-kcalloc-v2-1-2a99e93ec6e0@ethancedwards.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
When the filesystem performs file or filesystem synchronization (e.g.,
ext4_sync_file()), it queries the journal to determine whether to flush
the file device through jbd2_trans_will_send_data_barrier(). If the
target transaction has not started committing, it assumes that the
journal will submit the flush command, allowing the filesystem to bypass
a redundant flush command. However, this assumption is not always valid.
If the journal is not located on the filesystem device, the journal
commit thread will not submit the flush command unless the variable
->t_need_data_flush is set to 1. Consequently, the flush may be missed,
and data may be lost following a power failure or system crash, even if
the synchronization appears to succeed.
Unfortunately, we cannot determine with certainty whether the target
transaction will flush to the filesystem device before it commits.
However, if it has not started committing, it must be the running
transaction. Therefore, fix it by always set its t_need_data_flush to 1,
ensuring that the committing thread will flush the filesystem device.
Fixes: bbd2be369107 ("jbd2: Add function jbd2_trans_will_send_data_barrier()")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20241206111327.4171337-1-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This fixes an analogus bug that was fixed in xfs in commit
4b8d867ca6e2 ("xfs: don't over-report free space or inodes in
statvfs") where statfs can report misleading / incorrect information
where project quota is enabled, and the free space is less than the
remaining quota.
This commit will resolve a test failure in generic/762 which tests for
this bug.
Cc: stable@kernel.org
Fixes: 689c958cbe6b ("ext4: add project quota support")
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
commit 79add3a3f795e ("ext4: notify when discard is not supported")
noted that keeping the DISCARD flag is for possibility that the underlying
device might change in future even without file system remount. However,
this scenario has rarely occurred in practice on the device side. Even if
it does occur, it can be resolved with remount. Clearing the DISCARD flag
not only prevents confusion caused by mount options but also avoids
sending unnecessary discard commands.
Signed-off-by: Diangang Li <lidiangang@bytedance.com>
Link: https://patch.msgid.link/20250311021310.669524-1-lidiangang@bytedance.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Since the function jbd2_journal_unfile_buffer() is no longer called
anywhere after commit e5a120aeb57f ("jbd2: remove journal_head from
descriptor buffers"), so let's remove it.
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250306063240.157884-1-libaokun@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
capable() calls refer to enabled LSMs whether to permit or deny the
request. This is relevant in connection with SELinux, where a
capability check results in a policy decision and by default a denial
message on insufficient permission is issued.
It can lead to three undesired cases:
1. A denial message is generated, even in case the operation was an
unprivileged one and thus the syscall succeeded, creating noise.
2. To avoid the noise from 1. the policy writer adds a rule to ignore
those denial messages, hiding future syscalls, where the task
performs an actual privileged operation, leading to hidden limited
functionality of that task.
3. To avoid the noise from 1. the policy writer adds a rule to permit
the task the requested capability, while it does not need it,
violating the principle of least privilege.
Signed-off-by: Christian Göttsche <cgzones@googlemail.com>
Reviewed-by: Serge Hallyn <serge@hallyn.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250302160657.127253-2-cgoettsche@seltendoof.de
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Commit 196e402adf2e ("ext4: improve cr 0 / cr 1 group scanning") introduces
the sysfs control interface "mb_max_linear_groups" to address the problem
that rotational devices performance degrades when the "mb_optimize_scan"
feature is enabled, which may result in distant block group allocation.
However, the name of the interface was incorrect in the comment to the
ext4/mballoc.c file, and this patch fixes it, without further changes.
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://patch.msgid.link/20250224012005.689549-1-wozizhi@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
In __jbd2_journal_erase(), the block_stop parameter includes the last
block of a contiguous region; however, the calculation of byte_stop is
incorrect, as it does not account for the bytes in that last block.
Consequently, the page cache is not cleared properly, which occasionally
causes the ext4/050 test to fail.
Since block_stop operates on inclusion semantics, it involves repeated
increments and decrements by 1, significantly increasing the complexity
of the calculations. Optimize the calculation and fix the incorrect
byte_stop by make both block_stop and byte_stop to use exclusion
semantics.
This fixes a failure in fstests ext4/050.
Fixes: 01d5d96542fd ("ext4: add discard/zeroout flags to journal flush")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250217065955.3829229-1-yi.zhang@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Buffer heads are attached to folios, not to pages. Also
flush_dcache_page() is now deprecated in favour of flush_dcache_folio().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20250213182303.2133205-1-willy@infradead.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Otherwise, if ext4_inode_attach_jinode() fails, a hung task will
happen because filemap_invalidate_unlock() isn't called to unlock
mapping->invalidate_lock. Like this:
EXT4-fs error (device sda) in ext4_setattr:5557: Out of memory
INFO: task fsstress:374 blocked for more than 122 seconds.
Not tainted 6.14.0-rc1-next-20250206-xfstests-dirty #726
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:fsstress state:D stack:0 pid:374 tgid:374 ppid:373
task_flags:0x440140 flags:0x00000000
Call Trace:
<TASK>
__schedule+0x2c9/0x7f0
schedule+0x27/0xa0
schedule_preempt_disabled+0x15/0x30
rwsem_down_read_slowpath+0x278/0x4c0
down_read+0x59/0xb0
page_cache_ra_unbounded+0x65/0x1b0
filemap_get_pages+0x124/0x3e0
filemap_read+0x114/0x3d0
vfs_read+0x297/0x360
ksys_read+0x6c/0xe0
do_syscall_64+0x4b/0x110
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Fixes: c7fc0366c656 ("ext4: partial zero eof block on unaligned inode size extension")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Link: https://patch.msgid.link/20250213112247.3168709-1-libaokun@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
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