Linux: >> Linux Kernel >> 6.6.48 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
ext4: fix out-of-bound read in ext4_xattr_inode_dec_ref_all()
There's issue as follows:
BUG: KASAN: use-after-free in ext4_xattr_inode_dec_ref_all+0x6ff/0x790
Read of size 4 at addr ffff88807b003000 by task syz-executor.0/15172
CPU: 3 PID: 15172 Comm: syz-executor.0
Call Trace:
__dump_stack lib/dump_stack.c:82 [inline]
dump_stack+0xbe/0xfd lib/dump_stack.c:123
print_address_description.constprop.0+0x1e/0x280 mm/kasan/report.c:400
__kasan_report.cold+0x6c/0x84 mm/kasan/report.c:560
kasan_report+0x3a/0x50 mm/kasan/report.c:585
ext4_xattr_inode_dec_ref_all+0x6ff/0x790 fs/ext4/xattr.c:1137
ext4_xattr_delete_inode+0x4c7/0xda0 fs/ext4/xattr.c:2896
ext4_evict_inode+0xb3b/0x1670 fs/ext4/inode.c:323
evict+0x39f/0x880 fs/inode.c:622
iput_final fs/inode.c:1746 [inline]
iput fs/inode.c:1772 [inline]
iput+0x525/0x6c0 fs/inode.c:1758
ext4_orphan_cleanup fs/ext4/super.c:3298 [inline]
ext4_fill_super+0x8c57/0xba40 fs/ext4/super.c:5300
mount_bdev+0x355/0x410 fs/super.c:1446
legacy_get_tree+0xfe/0x220 fs/fs_context.c:611
vfs_get_tree+0x8d/0x2f0 fs/super.c:1576
do_new_mount fs/namespace.c:2983 [inline]
path_mount+0x119a/0x1ad0 fs/namespace.c:3316
do_mount+0xfc/0x110 fs/namespace.c:3329
__do_sys_mount fs/namespace.c:3540 [inline]
__se_sys_mount+0x219/0x2e0 fs/namespace.c:3514
do_syscall_64+0x33/0x40 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x67/0xd1
Memory state around the buggy address:
ffff88807b002f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88807b002f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807b003000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88807b003080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88807b003100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
Above issue happens as ext4_xattr_delete_inode() isn't check xattr
is valid if xattr is in inode.
To solve above issue call xattr_check_inode() check if xattr if valid
in inode. In fact, we can directly verify in ext4_iget_extra_inode(),
so that there is no divergent verification.
CVSS Score
7.1
EPSS Score
0.0
Published
2025-04-16
In the Linux kernel, the following vulnerability has been resolved:
md/md-bitmap: fix wrong bitmap_limit for clustermd when write sb
In clustermd, separate write-intent-bitmaps are used for each cluster
node:
0 4k 8k 12k
-------------------------------------------------------------------
| idle | md super | bm super [0] + bits |
| bm bits[0, contd] | bm super[1] + bits | bm bits[1, contd] |
| bm super[2] + bits | bm bits [2, contd] | bm super[3] + bits |
| bm bits [3, contd] | | |
So in node 1, pg_index in __write_sb_page() could equal to
bitmap->storage.file_pages. Then bitmap_limit will be calculated to
0. md_super_write() will be called with 0 size.
That means the first 4k sb area of node 1 will never be updated
through filemap_write_page().
This bug causes hang of mdadm/clustermd_tests/01r1_Grow_resize.
Here use (pg_index % bitmap->storage.file_pages) to make calculation
of bitmap_limit correct.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-04-16
In the Linux kernel, the following vulnerability has been resolved:
md/raid1,raid10: don't ignore IO flags
If blk-wbt is enabled by default, it's found that raid write performance
is quite bad because all IO are throttled by wbt of underlying disks,
due to flag REQ_IDLE is ignored. And turns out this behaviour exist since
blk-wbt is introduced.
Other than REQ_IDLE, other flags should not be ignored as well, for
example REQ_META can be set for filesystems, clearing it can cause priority
reverse problems; And REQ_NOWAIT should not be cleared as well, because
io will wait instead of failing directly in underlying disks.
Fix those problems by keep IO flags from master bio.
Fises: f51d46d0e7cb ("md: add support for REQ_NOWAIT")
CVSS Score
5.5
EPSS Score
0.0
Published
2025-04-16
In the Linux kernel, the following vulnerability has been resolved:
md: fix mddev uaf while iterating all_mddevs list
While iterating all_mddevs list from md_notify_reboot() and md_exit(),
list_for_each_entry_safe is used, and this can race with deletint the
next mddev, causing UAF:
t1:
spin_lock
//list_for_each_entry_safe(mddev, n, ...)
mddev_get(mddev1)
// assume mddev2 is the next entry
spin_unlock
t2:
//remove mddev2
...
mddev_free
spin_lock
list_del
spin_unlock
kfree(mddev2)
mddev_put(mddev1)
spin_lock
//continue dereference mddev2->all_mddevs
The old helper for_each_mddev() actually grab the reference of mddev2
while holding the lock, to prevent from being freed. This problem can be
fixed the same way, however, the code will be complex.
Hence switch to use list_for_each_entry, in this case mddev_put() can free
the mddev1 and it's not safe as well. Refer to md_seq_show(), also factor
out a helper mddev_put_locked() to fix this problem.
CVSS Score
7.8
EPSS Score
0.0
Published
2025-04-16
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix potential deadloop in prepare_compress_overwrite()
Jan Prusakowski reported a kernel hang issue as below:
When running xfstests on linux-next kernel (6.14.0-rc3, 6.12) I
encountered a problem in generic/475 test where fsstress process
gets blocked in __f2fs_write_data_pages() and the test hangs.
The options I used are:
MKFS_OPTIONS -- -O compression -O extra_attr -O project_quota -O quota /dev/vdc
MOUNT_OPTIONS -- -o acl,user_xattr -o discard,compress_extension=* /dev/vdc /vdc
INFO: task kworker/u8:0:11 blocked for more than 122 seconds.
Not tainted 6.14.0-rc3-xfstests-lockdep #1
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u8:0 state:D stack:0 pid:11 tgid:11 ppid:2 task_flags:0x4208160 flags:0x00004000
Workqueue: writeback wb_workfn (flush-253:0)
Call Trace:
<TASK>
__schedule+0x309/0x8e0
schedule+0x3a/0x100
schedule_preempt_disabled+0x15/0x30
__mutex_lock+0x59a/0xdb0
__f2fs_write_data_pages+0x3ac/0x400
do_writepages+0xe8/0x290
__writeback_single_inode+0x5c/0x360
writeback_sb_inodes+0x22f/0x570
wb_writeback+0xb0/0x410
wb_do_writeback+0x47/0x2f0
wb_workfn+0x5a/0x1c0
process_one_work+0x223/0x5b0
worker_thread+0x1d5/0x3c0
kthread+0xfd/0x230
ret_from_fork+0x31/0x50
ret_from_fork_asm+0x1a/0x30
</TASK>
The root cause is: once generic/475 starts toload error table to dm
device, f2fs_prepare_compress_overwrite() will loop reading compressed
cluster pages due to IO error, meanwhile it has held .writepages lock,
it can block all other writeback tasks.
Let's fix this issue w/ below changes:
- add f2fs_handle_page_eio() in prepare_compress_overwrite() to
detect IO error.
- detect cp_error earler in f2fs_read_multi_pages().
CVSS Score
5.5
EPSS Score
0.0
Published
2025-04-16
In the Linux kernel, the following vulnerability has been resolved:
bnxt_en: Mask the bd_cnt field in the TX BD properly
The bd_cnt field in the TX BD specifies the total number of BDs for
the TX packet. The bd_cnt field has 5 bits and the maximum number
supported is 32 with the value 0.
CONFIG_MAX_SKB_FRAGS can be modified and the total number of SKB
fragments can approach or exceed the maximum supported by the chip.
Add a macro to properly mask the bd_cnt field so that the value 32
will be properly masked and set to 0 in the bd_cnd field.
Without this patch, the out-of-range bd_cnt value will corrupt the
TX BD and may cause TX timeout.
The next patch will check for values exceeding 32.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-04-16
In the Linux kernel, the following vulnerability has been resolved:
ax25: Remove broken autobind
Binding AX25 socket by using the autobind feature leads to memory leaks
in ax25_connect() and also refcount leaks in ax25_release(). Memory
leak was detected with kmemleak:
================================================================
unreferenced object 0xffff8880253cd680 (size 96):
backtrace:
__kmalloc_node_track_caller_noprof (./include/linux/kmemleak.h:43)
kmemdup_noprof (mm/util.c:136)
ax25_rt_autobind (net/ax25/ax25_route.c:428)
ax25_connect (net/ax25/af_ax25.c:1282)
__sys_connect_file (net/socket.c:2045)
__sys_connect (net/socket.c:2064)
__x64_sys_connect (net/socket.c:2067)
do_syscall_64 (arch/x86/entry/common.c:52 arch/x86/entry/common.c:83)
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
================================================================
When socket is bound, refcounts must be incremented the way it is done
in ax25_bind() and ax25_setsockopt() (SO_BINDTODEVICE). In case of
autobind, the refcounts are not incremented.
This bug leads to the following issue reported by Syzkaller:
================================================================
ax25_connect(): syz-executor318 uses autobind, please contact jreuter@yaina.de
------------[ cut here ]------------
refcount_t: decrement hit 0; leaking memory.
WARNING: CPU: 0 PID: 5317 at lib/refcount.c:31 refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31
Modules linked in:
CPU: 0 UID: 0 PID: 5317 Comm: syz-executor318 Not tainted 6.14.0-rc4-syzkaller-00278-gece144f151ac #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:refcount_warn_saturate+0xfa/0x1d0 lib/refcount.c:31
...
Call Trace:
<TASK>
__refcount_dec include/linux/refcount.h:336 [inline]
refcount_dec include/linux/refcount.h:351 [inline]
ref_tracker_free+0x6af/0x7e0 lib/ref_tracker.c:236
netdev_tracker_free include/linux/netdevice.h:4302 [inline]
netdev_put include/linux/netdevice.h:4319 [inline]
ax25_release+0x368/0x960 net/ax25/af_ax25.c:1080
__sock_release net/socket.c:647 [inline]
sock_close+0xbc/0x240 net/socket.c:1398
__fput+0x3e9/0x9f0 fs/file_table.c:464
__do_sys_close fs/open.c:1580 [inline]
__se_sys_close fs/open.c:1565 [inline]
__x64_sys_close+0x7f/0x110 fs/open.c:1565
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
...
</TASK>
================================================================
Considering the issues above and the comments left in the code that say:
"check if we can remove this feature. It is broken."; "autobinding in this
may or may not work"; - it is better to completely remove this feature than
to fix it because it is broken and leads to various kinds of memory bugs.
Now calling connect() without first binding socket will result in an
error (-EINVAL). Userspace software that relies on the autobind feature
might get broken. However, this feature does not seem widely used with
this specific driver as it was not reliable at any point of time, and it
is already broken anyway. E.g. ax25-tools and ax25-apps packages for
popular distributions do not use the autobind feature for AF_AX25.
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-04-16
In the Linux kernel, the following vulnerability has been resolved:
net: Remove RTNL dance for SIOCBRADDIF and SIOCBRDELIF.
SIOCBRDELIF is passed to dev_ioctl() first and later forwarded to
br_ioctl_call(), which causes unnecessary RTNL dance and the splat
below [0] under RTNL pressure.
Let's say Thread A is trying to detach a device from a bridge and
Thread B is trying to remove the bridge.
In dev_ioctl(), Thread A bumps the bridge device's refcnt by
netdev_hold() and releases RTNL because the following br_ioctl_call()
also re-acquires RTNL.
In the race window, Thread B could acquire RTNL and try to remove
the bridge device. Then, rtnl_unlock() by Thread B will release RTNL
and wait for netdev_put() by Thread A.
Thread A, however, must hold RTNL after the unlock in dev_ifsioc(),
which may take long under RTNL pressure, resulting in the splat by
Thread B.
Thread A (SIOCBRDELIF) Thread B (SIOCBRDELBR)
---------------------- ----------------------
sock_ioctl sock_ioctl
`- sock_do_ioctl `- br_ioctl_call
`- dev_ioctl `- br_ioctl_stub
|- rtnl_lock |
|- dev_ifsioc '
' |- dev = __dev_get_by_name(...)
|- netdev_hold(dev, ...) .
/ |- rtnl_unlock ------. |
| |- br_ioctl_call `---> |- rtnl_lock
Race | | `- br_ioctl_stub |- br_del_bridge
Window | | | |- dev = __dev_get_by_name(...)
| | | May take long | `- br_dev_delete(dev, ...)
| | | under RTNL pressure | `- unregister_netdevice_queue(dev, ...)
| | | | `- rtnl_unlock
\ | |- rtnl_lock <-' `- netdev_run_todo
| |- ... `- netdev_run_todo
| `- rtnl_unlock |- __rtnl_unlock
| |- netdev_wait_allrefs_any
|- netdev_put(dev, ...) <----------------'
Wait refcnt decrement
and log splat below
To avoid blocking SIOCBRDELBR unnecessarily, let's not call
dev_ioctl() for SIOCBRADDIF and SIOCBRDELIF.
In the dev_ioctl() path, we do the following:
1. Copy struct ifreq by get_user_ifreq in sock_do_ioctl()
2. Check CAP_NET_ADMIN in dev_ioctl()
3. Call dev_load() in dev_ioctl()
4. Fetch the master dev from ifr.ifr_name in dev_ifsioc()
3. can be done by request_module() in br_ioctl_call(), so we move
1., 2., and 4. to br_ioctl_stub().
Note that 2. is also checked later in add_del_if(), but it's better
performed before RTNL.
SIOCBRADDIF and SIOCBRDELIF have been processed in dev_ioctl() since
the pre-git era, and there seems to be no specific reason to process
them there.
[0]:
unregister_netdevice: waiting for wpan3 to become free. Usage count = 2
ref_tracker: wpan3@ffff8880662d8608 has 1/1 users at
__netdev_tracker_alloc include/linux/netdevice.h:4282 [inline]
netdev_hold include/linux/netdevice.h:4311 [inline]
dev_ifsioc+0xc6a/0x1160 net/core/dev_ioctl.c:624
dev_ioctl+0x255/0x10c0 net/core/dev_ioctl.c:826
sock_do_ioctl+0x1ca/0x260 net/socket.c:1213
sock_ioctl+0x23a/0x6c0 net/socket.c:1318
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl fs/ioctl.c:892 [inline]
__x64_sys_ioctl+0x1a4/0x210 fs/ioctl.c:892
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
CVSS Score
5.5
EPSS Score
0.0
Published
2025-04-16
In the Linux kernel, the following vulnerability has been resolved:
ext4: avoid journaling sb update on error if journal is destroying
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.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-04-16
In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix block group refcount race in btrfs_create_pending_block_groups()
Block group creation is done in two phases, which results in a slightly
unintuitive property: a block group can be allocated/deallocated from
after btrfs_make_block_group() adds it to the space_info with
btrfs_add_bg_to_space_info(), but before creation is completely completed
in btrfs_create_pending_block_groups(). As a result, it is possible for a
block group to go unused and have 'btrfs_mark_bg_unused' called on it
concurrently with 'btrfs_create_pending_block_groups'. This causes a
number of issues, which were fixed with the block group flag
'BLOCK_GROUP_FLAG_NEW'.
However, this fix is not quite complete. Since it does not use the
unused_bg_lock, it is possible for the following race to occur:
btrfs_create_pending_block_groups btrfs_mark_bg_unused
if list_empty // false
list_del_init
clear_bit
else if (test_bit) // true
list_move_tail
And we get into the exact same broken ref count and invalid new_bgs
state for transaction cleanup that BLOCK_GROUP_FLAG_NEW was designed to
prevent.
The broken refcount aspect will result in a warning like:
[1272.943527] refcount_t: underflow; use-after-free.
[1272.943967] WARNING: CPU: 1 PID: 61 at lib/refcount.c:28 refcount_warn_saturate+0xba/0x110
[1272.944731] Modules linked in: btrfs virtio_net xor zstd_compress raid6_pq null_blk [last unloaded: btrfs]
[1272.945550] CPU: 1 UID: 0 PID: 61 Comm: kworker/u32:1 Kdump: loaded Tainted: G W 6.14.0-rc5+ #108
[1272.946368] Tainted: [W]=WARN
[1272.946585] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014
[1272.947273] Workqueue: btrfs_discard btrfs_discard_workfn [btrfs]
[1272.947788] RIP: 0010:refcount_warn_saturate+0xba/0x110
[1272.949532] RSP: 0018:ffffbf1200247df0 EFLAGS: 00010282
[1272.949901] RAX: 0000000000000000 RBX: ffffa14b00e3f800 RCX: 0000000000000000
[1272.950437] RDX: 0000000000000000 RSI: ffffbf1200247c78 RDI: 00000000ffffdfff
[1272.950986] RBP: ffffa14b00dc2860 R08: 00000000ffffdfff R09: ffffffff90526268
[1272.951512] R10: ffffffff904762c0 R11: 0000000063666572 R12: ffffa14b00dc28c0
[1272.952024] R13: 0000000000000000 R14: ffffa14b00dc2868 R15: 000001285dcd12c0
[1272.952850] FS: 0000000000000000(0000) GS:ffffa14d33c40000(0000) knlGS:0000000000000000
[1272.953458] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[1272.953931] CR2: 00007f838cbda000 CR3: 000000010104e000 CR4: 00000000000006f0
[1272.954474] Call Trace:
[1272.954655] <TASK>
[1272.954812] ? refcount_warn_saturate+0xba/0x110
[1272.955173] ? __warn.cold+0x93/0xd7
[1272.955487] ? refcount_warn_saturate+0xba/0x110
[1272.955816] ? report_bug+0xe7/0x120
[1272.956103] ? handle_bug+0x53/0x90
[1272.956424] ? exc_invalid_op+0x13/0x60
[1272.956700] ? asm_exc_invalid_op+0x16/0x20
[1272.957011] ? refcount_warn_saturate+0xba/0x110
[1272.957399] btrfs_discard_cancel_work.cold+0x26/0x2b [btrfs]
[1272.957853] btrfs_put_block_group.cold+0x5d/0x8e [btrfs]
[1272.958289] btrfs_discard_workfn+0x194/0x380 [btrfs]
[1272.958729] process_one_work+0x130/0x290
[1272.959026] worker_thread+0x2ea/0x420
[1272.959335] ? __pfx_worker_thread+0x10/0x10
[1272.959644] kthread+0xd7/0x1c0
[1272.959872] ? __pfx_kthread+0x10/0x10
[1272.960172] ret_from_fork+0x30/0x50
[1272.960474] ? __pfx_kthread+0x10/0x10
[1272.960745] ret_from_fork_asm+0x1a/0x30
[1272.961035] </TASK>
[1272.961238] ---[ end trace 0000000000000000 ]---
Though we have seen them in the async discard workfn as well. It is
most likely to happen after a relocation finishes which cancels discard,
tears down the block group, etc.
Fix this fully by taking the lock arou
---truncated---
CVSS Score
4.7
EPSS Score
0.0
Published
2025-04-16