Linux: >> Linux Kernel >> 4.14.191 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
cgroup: fix race between task migration and iteration
When a task is migrated out of a css_set, cgroup_migrate_add_task()
first moves it from cset->tasks to cset->mg_tasks via:
list_move_tail(&task->cg_list, &cset->mg_tasks);
If a css_task_iter currently has it->task_pos pointing to this task,
css_set_move_task() calls css_task_iter_skip() to keep the iterator
valid. However, since the task has already been moved to ->mg_tasks,
the iterator is advanced relative to the mg_tasks list instead of the
original tasks list. As a result, remaining tasks on cset->tasks, as
well as tasks queued on cset->mg_tasks, can be skipped by iteration.
Fix this by calling css_set_skip_task_iters() before unlinking
task->cg_list from cset->tasks. This advances all active iterators to
the next task on cset->tasks, so iteration continues correctly even
when a task is concurrently being migrated.
This race is hard to hit in practice without instrumentation, but it
can be reproduced by artificially slowing down cgroup_procs_show().
For example, on an Android device a temporary
/sys/kernel/cgroup/cgroup_test knob can be added to inject a delay
into cgroup_procs_show(), and then:
1) Spawn three long-running tasks (PIDs 101, 102, 103).
2) Create a test cgroup and move the tasks into it.
3) Enable a large delay via /sys/kernel/cgroup/cgroup_test.
4) In one shell, read cgroup.procs from the test cgroup.
5) Within the delay window, in another shell migrate PID 102 by
writing it to a different cgroup.procs file.
Under this setup, cgroup.procs can intermittently show only PID 101
while skipping PID 103. Once the migration completes, reading the
file again shows all tasks as expected.
Note that this change does not allow removing the existing
css_set_skip_task_iters() call in css_set_move_task(). The new call
in cgroup_migrate_add_task() only handles iterators that are racing
with migration while the task is still on cset->tasks. Iterators may
also start after the task has been moved to cset->mg_tasks. If we
dropped css_set_skip_task_iters() from css_set_move_task(), such
iterators could keep task_pos pointing to a migrating task, causing
css_task_iter_advance() to malfunction on the destination css_set,
up to and including crashes or infinite loops.
The race window between migration and iteration is very small, and
css_task_iter is not on a hot path. In the worst case, when an
iterator is positioned on the first thread of the migrating process,
cgroup_migrate_add_task() may have to skip multiple tasks via
css_set_skip_task_iters(). However, this only happens when migration
and iteration actually race, so the performance impact is negligible
compared to the correctness fix provided here.
CVSS Score
4.7
EPSS Score
0.0
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
e1000/e1000e: Fix leak in DMA error cleanup
If an error is encountered while mapping TX buffers, the driver should
unmap any buffers already mapped for that skb.
Because count is incremented after a successful mapping, it will always
match the correct number of unmappings needed when dma_error is reached.
Decrementing count before the while loop in dma_error causes an
off-by-one error. If any mapping was successful before an unsuccessful
mapping, exactly one DMA mapping would leak.
In these commits, a faulty while condition caused an infinite loop in
dma_error:
Commit 03b1320dfcee ("e1000e: remove use of skb_dma_map from e1000e
driver")
Commit 602c0554d7b0 ("e1000: remove use of skb_dma_map from e1000 driver")
Commit c1fa347f20f1 ("e1000/e1000e/igb/igbvf/ixgb/ixgbe: Fix tests of
unsigned in *_tx_map()") fixed the infinite loop, but introduced the
off-by-one error.
This issue may still exist in the igbvf driver, but I did not address it
in this patch.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
usb: yurex: fix race in probe
The bbu member of the descriptor must be set to the value
standing for uninitialized values before the URB whose
completion handler sets bbu is submitted. Otherwise there is
a window during which probing can overwrite already retrieved
data.
CVSS Score
4.7
EPSS Score
0.0
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_ncm: Fix net_device lifecycle with device_move
The network device outlived its parent gadget device during
disconnection, resulting in dangling sysfs links and null pointer
dereference problems.
A prior attempt to solve this by removing SET_NETDEV_DEV entirely [1]
was reverted due to power management ordering concerns and a NO-CARRIER
regression.
A subsequent attempt to defer net_device allocation to bind [2] broke
1:1 mapping between function instance and network device, making it
impossible for configfs to report the resolved interface name. This
results in a regression where the DHCP server fails on pmOS.
Use device_move to reparent the net_device between the gadget device and
/sys/devices/virtual/ across bind/unbind cycles. This preserves the
network interface across USB reconnection, allowing the DHCP server to
retain their binding.
Introduce gether_attach_gadget()/gether_detach_gadget() helpers and use
__free(detach_gadget) macro to undo attachment on bind failure. The
bind_count ensures device_move executes only on the first bind.
[1] https://lore.kernel.org/lkml/f2a4f9847617a0929d62025748384092e5f35cce.camel@crapouillou.net/
[2] https://lore.kernel.org/linux-usb/795ea759-7eaf-4f78-81f4-01ffbf2d7961@ixit.cz/
CVSS Score
5.5
EPSS Score
0.0
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: f_tcm: Fix NULL pointer dereferences in nexus handling
The `tpg->tpg_nexus` pointer in the USB Target driver is dynamically
managed and tied to userspace configuration via ConfigFS. It can be
NULL if the USB host sends requests before the nexus is fully
established or immediately after it is dropped.
Currently, functions like `bot_submit_command()` and the data
transfer paths retrieve `tv_nexus = tpg->tpg_nexus` and immediately
dereference `tv_nexus->tvn_se_sess` without any validation. If a
malicious or misconfigured USB host sends a BOT (Bulk-Only Transport)
command during this race window, it triggers a NULL pointer
dereference, leading to a kernel panic (local DoS).
This exposes an inconsistent API usage within the module, as peer
functions like `usbg_submit_command()` and `bot_send_bad_response()`
correctly implement a NULL check for `tv_nexus` before proceeding.
Fix this by bringing consistency to the nexus handling. Add the
missing `if (!tv_nexus)` checks to the vulnerable BOT command and
request processing paths, aborting the command gracefully with an
error instead of crashing the system.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
usb: image: mdc800: kill download URB on timeout
mdc800_device_read() submits download_urb and waits for completion.
If the timeout fires and the device has not responded, the function
returns without killing the URB, leaving it active.
A subsequent read() resubmits the same URB while it is still
in-flight, triggering the WARN in usb_submit_urb():
"URB submitted while active"
Check the return value of wait_event_timeout() and kill the URB if
it indicates timeout, ensuring the URB is complete before its status
is inspected or the URB is resubmitted.
Similar to
- commit 372c93131998 ("USB: yurex: fix control-URB timeout handling")
- commit b98d5000c505 ("media: rc: iguanair: handle timeouts")
CVSS Score
5.5
EPSS Score
0.0
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
usb: renesas_usbhs: fix use-after-free in ISR during device removal
In usbhs_remove(), the driver frees resources (including the pipe array)
while the interrupt handler (usbhs_interrupt) is still registered. If an
interrupt fires after usbhs_pipe_remove() but before the driver is fully
unbound, the ISR may access freed memory, causing a use-after-free.
Fix this by calling devm_free_irq() before freeing resources. This ensures
the interrupt handler is both disabled and synchronized (waits for any
running ISR to complete) before usbhs_pipe_remove() is called.
CVSS Score
7.8
EPSS Score
0.0
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
usb: class: cdc-wdm: fix reordering issue in read code path
Quoting the bug report:
Due to compiler optimization or CPU out-of-order execution, the
desc->length update can be reordered before the memmove. If this
happens, wdm_read() can see the new length and call copy_to_user() on
uninitialized memory. This also violates LKMM data race rules [1].
Fix it by using WRITE_ONCE and memory barriers.
CVSS Score
7.1
EPSS Score
0.0
Published
2026-05-08
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
0.0
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
scsi: hisi_sas: Fix NULL pointer exception during user_scan()
user_scan() invokes updated sas_user_scan() for channel 0, and if
successful, iteratively scans remaining channels (1 to shost->max_channel)
via scsi_scan_host_selected() in commit 37c4e72b0651 ("scsi: Fix
sas_user_scan() to handle wildcard and multi-channel scans"). However,
hisi_sas supports only one channel, and the current value of max_channel is
1. sas_user_scan() for channel 1 will trigger the following NULL pointer
exception:
[ 441.554662] Unable to handle kernel NULL pointer dereference at virtual address 00000000000008b0
[ 441.554699] Mem abort info:
[ 441.554710] ESR = 0x0000000096000004
[ 441.554718] EC = 0x25: DABT (current EL), IL = 32 bits
[ 441.554723] SET = 0, FnV = 0
[ 441.554726] EA = 0, S1PTW = 0
[ 441.554730] FSC = 0x04: level 0 translation fault
[ 441.554735] Data abort info:
[ 441.554737] ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[ 441.554742] CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[ 441.554747] GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[ 441.554752] user pgtable: 4k pages, 48-bit VAs, pgdp=00000828377a6000
[ 441.554757] [00000000000008b0] pgd=0000000000000000, p4d=0000000000000000
[ 441.554769] Internal error: Oops: 0000000096000004 [#1] SMP
[ 441.629589] Modules linked in: arm_spe_pmu arm_smmuv3_pmu tpm_tis_spi hisi_uncore_sllc_pmu hisi_uncore_pa_pmu hisi_uncore_l3c_pmu hisi_uncore_hha_pmu hisi_uncore_ddrc_pmu hisi_uncore_cpa_pmu hns3_pmu hisi_ptt hisi_pcie_pmu tpm_tis_core spidev spi_hisi_sfc_v3xx hisi_uncore_pmu spi_dw_mmio fuse hclge hclge_common hisi_sec2 hisi_hpre hisi_zip hisi_qm hns3 hisi_sas_v3_hw sm3_ce sbsa_gwdt hnae3 hisi_sas_main uacce hisi_dma i2c_hisi dm_mirror dm_region_hash dm_log dm_mod
[ 441.670819] CPU: 46 UID: 0 PID: 6994 Comm: bash Kdump: loaded Not tainted 7.0.0-rc2+ #84 PREEMPT
[ 441.691327] pstate: 81400009 (Nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[ 441.698277] pc : sas_find_dev_by_rphy+0x44/0x118
[ 441.702896] lr : sas_find_dev_by_rphy+0x3c/0x118
[ 441.707502] sp : ffff80009abbba40
[ 441.710805] x29: ffff80009abbba40 x28: ffff082819a40008 x27: ffff082810c37c08
[ 441.717930] x26: ffff082810c37c28 x25: ffff082819a40290 x24: ffff082810c37c00
[ 441.725054] x23: 0000000000000000 x22: 0000000000000001 x21: ffff082819a40000
[ 441.732179] x20: ffff082819a40290 x19: 0000000000000000 x18: 0000000000000020
[ 441.739304] x17: 0000000000000000 x16: ffffb5dad6bda690 x15: 00000000ffffffff
[ 441.746428] x14: ffff082814c3b26c x13: 00000000ffffffff x12: ffff082814c3b26a
[ 441.753553] x11: 00000000000000c0 x10: 000000000000003a x9 : ffffb5dad5ea94f4
[ 441.760678] x8 : 000000000000003a x7 : ffff80009abbbab0 x6 : 0000000000000030
[ 441.767802] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
[ 441.774926] x2 : ffff08280f35a300 x1 : ffffb5dad7127180 x0 : 0000000000000000
[ 441.782053] Call trace:
[ 441.784488] sas_find_dev_by_rphy+0x44/0x118 (P)
[ 441.789095] sas_target_alloc+0x24/0xb0
[ 441.792920] scsi_alloc_target+0x290/0x330
[ 441.797010] __scsi_scan_target+0x88/0x258
[ 441.801096] scsi_scan_channel+0x74/0xb8
[ 441.805008] scsi_scan_host_selected+0x170/0x188
[ 441.809615] sas_user_scan+0xfc/0x148
[ 441.813267] store_scan+0x10c/0x180
[ 441.816743] dev_attr_store+0x20/0x40
[ 441.820398] sysfs_kf_write+0x84/0xa8
[ 441.824054] kernfs_fop_write_iter+0x130/0x1c8
[ 441.828487] vfs_write+0x2c0/0x370
[ 441.831880] ksys_write+0x74/0x118
[ 441.835271] __arm64_sys_write+0x24/0x38
[ 441.839182] invoke_syscall+0x50/0x120
[ 441.842919] el0_svc_common.constprop.0+0xc8/0xf0
[ 441.847611] do_el0_svc+0x24/0x38
[ 441.850913] el0_svc+0x38/0x158
[ 441.854043] el0t_64_sync_handler+0xa0/0xe8
[ 441.858214] el0t_64_sync+0x1ac/0x1b0
[ 441.861865] Code: aa1303e0 97ff70a8 34ffff80 d10a4273 (f9445a75)
[ 441.867946] ---[ end trace 0000000000000000 ]---
Therefore
---truncated---
CVSS Score
5.5
EPSS Score
0.0
Published
2026-05-08