Linux: >> Linux Kernel >> 2.6.32 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
USB: core: Limit the length of unkillable synchronous timeouts
The usb_control_msg(), usb_bulk_msg(), and usb_interrupt_msg() APIs in
usbcore allow unlimited timeout durations. And since they use
uninterruptible waits, this leaves open the possibility of hanging a
task for an indefinitely long time, with no way to kill it short of
unplugging the target device.
To prevent this sort of problem, enforce a maximum limit on the length
of these unkillable timeouts. The limit chosen here, somewhat
arbitrarily, is 60 seconds. On many systems (although not all) this
is short enough to avoid triggering the kernel's hung-task detector.
In addition, clear up the ambiguity of negative timeout values by
treating them the same as 0, i.e., using the maximum allowed timeout.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
powerpc, perf: Check that current->mm is alive before getting user callchain
It may happen that mm is already released, which leads to kernel panic.
This adds the NULL check for current->mm, similarly to
commit 20afc60f892d ("x86, perf: Check that current->mm is alive before getting user callchain").
I was getting this panic when running a profiling BPF program
(profile.py from bcc-tools):
[26215.051935] Kernel attempted to read user page (588) - exploit attempt? (uid: 0)
[26215.051950] BUG: Kernel NULL pointer dereference on read at 0x00000588
[26215.051952] Faulting instruction address: 0xc00000000020fac0
[26215.051957] Oops: Kernel access of bad area, sig: 11 [#1]
[...]
[26215.052049] Call Trace:
[26215.052050] [c000000061da6d30] [c00000000020fc10] perf_callchain_user_64+0x2d0/0x490 (unreliable)
[26215.052054] [c000000061da6dc0] [c00000000020f92c] perf_callchain_user+0x1c/0x30
[26215.052057] [c000000061da6de0] [c0000000005ab2a0] get_perf_callchain+0x100/0x360
[26215.052063] [c000000061da6e70] [c000000000573bc8] bpf_get_stackid+0x88/0xf0
[26215.052067] [c000000061da6ea0] [c008000000042258] bpf_prog_16d4ab9ab662f669_do_perf_event+0xf8/0x274
[...]
In addition, move storing the top-level stack entry to generic
perf_callchain_user to make sure the top-evel entry is always captured,
even if current->mm is NULL.
[Maddy: fixed message to avoid checkpatch format style error]
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
net/tcp-md5: Fix MAC comparison to be constant-time
To prevent timing attacks, MACs need to be compared in constant
time. Use the appropriate helper function for this.
CVSS Score
9.4
EPSS Score
0.004
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
x86/apic: Disable x2apic on resume if the kernel expects so
When resuming from s2ram, firmware may re-enable x2apic mode, which may have
been disabled by the kernel during boot either because it doesn't support IRQ
remapping or for other reasons. This causes the kernel to continue using the
xapic interface, while the hardware is in x2apic mode, which causes hangs.
This happens on defconfig + bare metal + s2ram.
Fix this in lapic_resume() by disabling x2apic if the kernel expects it to be
disabled, i.e. when x2apic_mode = 0.
The ACPI v6.6 spec, Section 16.3 [1] says firmware restores either the
pre-sleep configuration or initial boot configuration for each CPU, including
MSR state:
When executing from the power-on reset vector as a result of waking from an
S2 or S3 sleep state, the platform firmware performs only the hardware
initialization required to restore the system to either the state the
platform was in prior to the initial operating system boot, or to the
pre-sleep configuration state. In multiprocessor systems, non-boot
processors should be placed in the same state as prior to the initial
operating system boot.
(further ahead)
If this is an S2 or S3 wake, then the platform runtime firmware restores
minimum context of the system before jumping to the waking vector. This
includes:
CPU configuration. Platform runtime firmware restores the pre-sleep
configuration or initial boot configuration of each CPU (MSR, MTRR,
firmware update, SMBase, and so on). Interrupts must be disabled (for
IA-32 processors, disabled by CLI instruction).
(and other things)
So at least as per the spec, re-enablement of x2apic by the firmware is
allowed if "x2apic on" is a part of the initial boot configuration.
[1] https://uefi.org/specs/ACPI/6.6/16_Waking_and_Sleeping.html#initialization
[ bp: Massage. ]
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
comedi: Reinit dev->spinlock between attachments to low-level drivers
`struct comedi_device` is the main controlling structure for a COMEDI
device created by the COMEDI subsystem. It contains a member `spinlock`
containing a spin-lock that is initialized by the COMEDI subsystem, but
is reserved for use by a low-level driver attached to the COMEDI device
(at least since commit 25436dc9d84f ("Staging: comedi: remove RT
code")).
Some COMEDI devices (those created on initialization of the COMEDI
subsystem when the "comedi.comedi_num_legacy_minors" parameter is
non-zero) can be attached to different low-level drivers over their
lifetime using the `COMEDI_DEVCONFIG` ioctl command. This can result in
inconsistent lock states being reported when there is a mismatch in the
spin-lock locking levels used by each low-level driver to which the
COMEDI device has been attached. Fix it by reinitializing
`dev->spinlock` before calling the low-level driver's `attach` function
pointer if `CONFIG_LOCKDEP` is enabled.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
ACPI: processor: Fix NULL-pointer dereference in acpi_processor_errata_piix4()
In acpi_processor_errata_piix4(), the pointer dev is first assigned an IDE
device and then reassigned an ISA device:
dev = pci_get_subsys(..., PCI_DEVICE_ID_INTEL_82371AB, ...);
dev = pci_get_subsys(..., PCI_DEVICE_ID_INTEL_82371AB_0, ...);
If the first lookup succeeds but the second fails, dev becomes NULL. This
leads to a potential null-pointer dereference when dev_dbg() is called:
if (errata.piix4.bmisx)
dev_dbg(&dev->dev, ...);
To prevent this, use two temporary pointers and retrieve each device
independently, avoiding overwriting dev with a possible NULL value.
[ rjw: Subject adjustment, added an empty code line ]
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
dm: remove fake timeout to avoid leak request
Since commit 15f73f5b3e59 ("blk-mq: move failure injection out of
blk_mq_complete_request"), drivers are responsible for calling
blk_should_fake_timeout() at appropriate code paths and opportunities.
However, the dm driver does not implement its own timeout handler and
relies on the timeout handling of its slave devices.
If an io-timeout-fail error is injected to a dm device, the request
will be leaked and never completed, causing tasks to hang indefinitely.
Reproduce:
1. prepare dm which has iscsi slave device
2. inject io-timeout-fail to dm
echo 1 >/sys/class/block/dm-0/io-timeout-fail
echo 100 >/sys/kernel/debug/fail_io_timeout/probability
echo 10 >/sys/kernel/debug/fail_io_timeout/times
3. read/write dm
4. iscsiadm -m node -u
Result: hang task like below
[ 862.243768] INFO: task kworker/u514:2:151 blocked for more than 122 seconds.
[ 862.244133] Tainted: G E 6.19.0-rc1+ #51
[ 862.244337] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 862.244718] task:kworker/u514:2 state:D stack:0 pid:151 tgid:151 ppid:2 task_flags:0x4288060 flags:0x00080000
[ 862.245024] Workqueue: iscsi_ctrl_3:1 __iscsi_unbind_session [scsi_transport_iscsi]
[ 862.245264] Call Trace:
[ 862.245587] <TASK>
[ 862.245814] __schedule+0x810/0x15c0
[ 862.246557] schedule+0x69/0x180
[ 862.246760] blk_mq_freeze_queue_wait+0xde/0x120
[ 862.247688] elevator_change+0x16d/0x460
[ 862.247893] elevator_set_none+0x87/0xf0
[ 862.248798] blk_unregister_queue+0x12e/0x2a0
[ 862.248995] __del_gendisk+0x231/0x7e0
[ 862.250143] del_gendisk+0x12f/0x1d0
[ 862.250339] sd_remove+0x85/0x130 [sd_mod]
[ 862.250650] device_release_driver_internal+0x36d/0x530
[ 862.250849] bus_remove_device+0x1dd/0x3f0
[ 862.251042] device_del+0x38a/0x930
[ 862.252095] __scsi_remove_device+0x293/0x360
[ 862.252291] scsi_remove_target+0x486/0x760
[ 862.252654] __iscsi_unbind_session+0x18a/0x3e0 [scsi_transport_iscsi]
[ 862.252886] process_one_work+0x633/0xe50
[ 862.253101] worker_thread+0x6df/0xf10
[ 862.253647] kthread+0x36d/0x720
[ 862.254533] ret_from_fork+0x2a6/0x470
[ 862.255852] ret_from_fork_asm+0x1a/0x30
[ 862.256037] </TASK>
Remove the blk_should_fake_timeout() check from dm, as dm has no
native timeout handling and should not attempt to fake timeouts.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
btrfs: don't BUG() on unexpected delayed ref type in run_one_delayed_ref()
There is no need to BUG(), we can just return an error and log an error
message.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
gfs2: fiemap page fault fix
In gfs2_fiemap(), we are calling iomap_fiemap() while holding the inode
glock. This can lead to recursive glock taking if the fiemap buffer is
memory mapped to the same inode and accessing it triggers a page fault.
Fix by disabling page faults for iomap_fiemap() and faulting in the
buffer by hand if necessary.
Fixes xfstest generic/742.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-06
In the Linux kernel, the following vulnerability has been resolved:
hfsplus: pretend special inodes as regular files
Since commit af153bb63a33 ("vfs: catch invalid modes in may_open()")
requires any inode be one of S_IFDIR/S_IFLNK/S_IFREG/S_IFCHR/S_IFBLK/
S_IFIFO/S_IFSOCK type, use S_IFREG for special inodes.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-05-06