Linux: >> Linux Kernel >> 3.3.4 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
btrfs: reject root items with drop_progress and zero drop_level
[BUG]
When recovering relocation at mount time, merge_reloc_root() and
btrfs_drop_snapshot() both use BUG_ON(level == 0) to guard against
an impossible state: a non-zero drop_progress combined with a zero
drop_level in a root_item, which can be triggered:
------------[ cut here ]------------
kernel BUG at fs/btrfs/relocation.c:1545!
Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI
CPU: 1 UID: 0 PID: 283 ... Tainted: 6.18.0+ #16 PREEMPT(voluntary)
Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
Hardware name: QEMU Ubuntu 24.04 PC v2, BIOS 1.16.3-debian-1.16.3-2
RIP: 0010:merge_reloc_root+0x1266/0x1650 fs/btrfs/relocation.c:1545
Code: ffff0000 00004589 d7e9acfa ffffe8a1 79bafebe 02000000
Call Trace:
merge_reloc_roots+0x295/0x890 fs/btrfs/relocation.c:1861
btrfs_recover_relocation+0xd6e/0x11d0 fs/btrfs/relocation.c:4195
btrfs_start_pre_rw_mount+0xa4d/0x1810 fs/btrfs/disk-io.c:3130
open_ctree+0x5824/0x5fe0 fs/btrfs/disk-io.c:3640
btrfs_fill_super fs/btrfs/super.c:987 [inline]
btrfs_get_tree_super fs/btrfs/super.c:1951 [inline]
btrfs_get_tree_subvol fs/btrfs/super.c:2094 [inline]
btrfs_get_tree+0x111c/0x2190 fs/btrfs/super.c:2128
vfs_get_tree+0x9a/0x370 fs/super.c:1758
fc_mount fs/namespace.c:1199 [inline]
do_new_mount_fc fs/namespace.c:3642 [inline]
do_new_mount fs/namespace.c:3718 [inline]
path_mount+0x5b8/0x1ea0 fs/namespace.c:4028
do_mount fs/namespace.c:4041 [inline]
__do_sys_mount fs/namespace.c:4229 [inline]
__se_sys_mount fs/namespace.c:4206 [inline]
__x64_sys_mount+0x282/0x320 fs/namespace.c:4206
...
RIP: 0033:0x7f969c9a8fde
Code: 0f1f4000 48c7c2b0 fffffff7 d8648902 b8ffffff ffc3660f
---[ end trace 0000000000000000 ]---
The bug is reproducible on 7.0.0-rc2-next-20260310 with our dynamic
metadata fuzzing tool that corrupts btrfs metadata at runtime.
[CAUSE]
A non-zero drop_progress.objectid means an interrupted
btrfs_drop_snapshot() left a resume point on disk, and in that case
drop_level must be greater than 0 because the checkpoint is only
saved at internal node levels.
Although this invariant is enforced when the kernel writes the root
item, it is not validated when the root item is read back from disk.
That allows on-disk corruption to provide an invalid state with
drop_progress.objectid != 0 and drop_level == 0.
When relocation recovery later processes such a root item,
merge_reloc_root() reads drop_level and hits BUG_ON(level == 0). The
same invalid metadata can also trigger the corresponding BUG_ON() in
btrfs_drop_snapshot().
[FIX]
Fix this by validating the root_item invariant in tree-checker when
reading root items from disk: if drop_progress.objectid is non-zero,
drop_level must also be non-zero. Reject such malformed metadata with
-EUCLEAN before it reaches merge_reloc_root() or btrfs_drop_snapshot()
and triggers the BUG_ON.
After the fix, the same corruption is correctly rejected by tree-checker
and the BUG_ON is no longer triggered.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
ip6_tunnel: clear skb2->cb[] in ip4ip6_err()
Oskar Kjos reported the following problem.
ip4ip6_err() calls icmp_send() on a cloned skb whose cb[] was written
by the IPv6 receive path as struct inet6_skb_parm. icmp_send() passes
IPCB(skb2) to __ip_options_echo(), which interprets that cb[] region
as struct inet_skb_parm (IPv4). The layouts differ: inet6_skb_parm.nhoff
at offset 14 overlaps inet_skb_parm.opt.rr, producing a non-zero rr
value. __ip_options_echo() then reads optlen from attacker-controlled
packet data at sptr[rr+1] and copies that many bytes into dopt->__data,
a fixed 40-byte stack buffer (IP_OPTIONS_DATA_FIXED_SIZE).
To fix this we clear skb2->cb[], as suggested by Oskar Kjos.
Also add minimal IPv4 header validation (version == 4, ihl >= 5).
CVSS Score
9.8
EPSS Score
0.005
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
net/x25: Fix potential double free of skb
When alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at
line 48 and returns 1 (error).
This error propagates back through the call chain:
x25_queue_rx_frame returns 1
|
v
x25_state3_machine receives the return value 1 and takes the else
branch at line 278, setting queued=0 and returning 0
|
v
x25_process_rx_frame returns queued=0
|
v
x25_backlog_rcv at line 452 sees queued=0 and calls kfree_skb(skb)
again
This would free the same skb twice. Looking at x25_backlog_rcv:
net/x25/x25_in.c:x25_backlog_rcv() {
...
queued = x25_process_rx_frame(sk, skb);
...
if (!queued)
kfree_skb(skb);
}
CVSS Score
9.8
EPSS Score
0.005
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
ALSA: ctxfi: Check the error for index mapping
The ctxfi driver blindly assumed a proper value returned from
daio_device_index(), but it's not always true. Add a proper error
check to deal with the error from the function.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
ALSA: caiaq: fix stack out-of-bounds read in init_card
The loop creates a whitespace-stripped copy of the card shortname
where `len < sizeof(card->id)` is used for the bounds check. Since
sizeof(card->id) is 16 and the local id buffer is also 16 bytes,
writing 16 non-space characters fills the entire buffer,
overwriting the terminating nullbyte.
When this non-null-terminated string is later passed to
snd_card_set_id() -> copy_valid_id_string(), the function scans
forward with `while (*nid && ...)` and reads past the end of the
stack buffer, reading the contents of the stack.
A USB device with a product name containing many non-ASCII, non-space
characters (e.g. multibyte UTF-8) will reliably trigger this as follows:
BUG: KASAN: stack-out-of-bounds in copy_valid_id_string
sound/core/init.c:696 [inline]
BUG: KASAN: stack-out-of-bounds in snd_card_set_id_no_lock+0x698/0x74c
sound/core/init.c:718
The off-by-one has been present since commit bafeee5b1f8d ("ALSA:
snd_usb_caiaq: give better shortname") from June 2009 (v2.6.31-rc1),
which first introduced this whitespace-stripping loop. The original
code never accounted for the null terminator when bounding the copy.
Fix this by changing the loop bound to `sizeof(card->id) - 1`,
ensuring at least one byte remains as the null terminator.
CVSS Score
7.1
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
comedi: me_daq: Fix potential overrun of firmware buffer
`me2600_xilinx_download()` loads the firmware that was requested by
`request_firmware()`. It is possible for it to overrun the source
buffer because it blindly trusts the file format. It reads a data
stream length from the first 4 bytes into variable `file_length` and
reads the data stream contents of length `file_length` from offset 16
onwards. Although it checks that the supplied firmware is at least 16
bytes long, it does not check that it is long enough to contain the data
stream.
Add a test to ensure that the supplied firmware is long enough to
contain the header and the data stream. On failure, log an error and
return `-EINVAL`.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
comedi: ni_atmio16d: Fix invalid clean-up after failed attach
If the driver's COMEDI "attach" handler function (`atmio16d_attach()`)
returns an error, the COMEDI core will call the driver's "detach"
handler function (`atmio16d_detach()`) to clean up. This calls
`reset_atmio16d()` unconditionally, but depending on where the error
occurred in the attach handler, the device may not have been
sufficiently initialized to call `reset_atmio16d()`. It uses
`dev->iobase` as the I/O port base address and `dev->private` as the
pointer to the COMEDI device's private data structure. `dev->iobase`
may still be set to its initial value of 0, which would result in
undesired writes to low I/O port addresses. `dev->private` may still be
`NULL`, which would result in null pointer dereferences.
Fix `atmio16d_detach()` by checking that `dev->private` is valid
(non-null) before calling `reset_atmio16d()`. This implies that
`dev->iobase` was set correctly since that is set up before
`dev->private`.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
comedi: dt2815: add hardware detection to prevent crash
The dt2815 driver crashes when attached to I/O ports without actual
hardware present. This occurs because syzkaller or users can attach
the driver to arbitrary I/O addresses via COMEDI_DEVCONFIG ioctl.
When no hardware exists at the specified port, inb() operations return
0xff (floating bus), but outb() operations can trigger page faults due
to undefined behavior, especially under race conditions:
BUG: unable to handle page fault for address: 000000007fffff90
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
RIP: 0010:dt2815_attach+0x6e0/0x1110
Add hardware detection by reading the status register before attempting
any write operations. If the read returns 0xff, assume no hardware is
present and fail the attach with -ENODEV. This prevents crashes from
outb() operations on non-existent hardware.
CVSS Score
4.7
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: u_ether: Fix race between gether_disconnect and eth_stop
A race condition between gether_disconnect() and eth_stop() leads to a
NULL pointer dereference. Specifically, if eth_stop() is triggered
concurrently while gether_disconnect() is tearing down the endpoints,
eth_stop() attempts to access the cleared endpoint descriptor, causing
the following NPE:
Unable to handle kernel NULL pointer dereference
Call trace:
__dwc3_gadget_ep_enable+0x60/0x788
dwc3_gadget_ep_enable+0x70/0xe4
usb_ep_enable+0x60/0x15c
eth_stop+0xb8/0x108
Because eth_stop() crashes while holding the dev->lock, the thread
running gether_disconnect() fails to acquire the same lock and spins
forever, resulting in a hardlockup:
Core - Debugging Information for Hardlockup core(7)
Call trace:
queued_spin_lock_slowpath+0x94/0x488
_raw_spin_lock+0x64/0x6c
gether_disconnect+0x19c/0x1e8
ncm_set_alt+0x68/0x1a0
composite_setup+0x6a0/0xc50
The root cause is that the clearing of dev->port_usb in
gether_disconnect() is delayed until the end of the function.
Move the clearing of dev->port_usb to the very beginning of
gether_disconnect() while holding dev->lock. This cuts off the link
immediately, ensuring eth_stop() will see dev->port_usb as NULL and
safely bail out.
CVSS Score
4.7
EPSS Score
0.001
Published
2026-05-01
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_uac1_legacy: validate control request size
f_audio_complete() copies req->length bytes into a 4-byte stack
variable:
u32 data = 0;
memcpy(&data, req->buf, req->length);
req->length is derived from the host-controlled USB request path,
which can lead to a stack out-of-bounds write.
Validate req->actual against the expected payload size for the
supported control selectors and decode only the expected amount
of data.
This avoids copying a host-influenced length into a fixed-size
stack object.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-05-01