Linux: >> Linux Kernel >> 5.10.121 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: usbtmc: Use usb_bulk_msg_killable() with user-specified timeouts
The usbtmc driver accepts timeout values specified by the user in an
ioctl command, and uses these timeouts for some usb_bulk_msg() calls.
Since the user can specify arbitrarily long timeouts and
usb_bulk_msg() uses unkillable waits, call usb_bulk_msg_killable()
instead to avoid the possibility of the user hanging a kernel thread
indefinitely.
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: xhci: Fix memory leak in xhci_disable_slot()
xhci_alloc_command() allocates a command structure and, when the
second argument is true, also allocates a completion structure.
Currently, the error handling path in xhci_disable_slot() only frees
the command structure using kfree(), causing the completion structure
to leak.
Use xhci_free_command() instead of kfree(). xhci_free_command() correctly
frees both the command structure and the associated completion structure.
Since the command structure is allocated with zero-initialization,
command->in_ctx is NULL and will not be erroneously freed by
xhci_free_command().
This bug was found using an experimental static analysis tool we are
developing. The tool is based on the LLVM framework and is specifically
designed to detect memory management issues. It is currently under
active development and not yet publicly available, but we plan to
open-source it after our research is published.
The bug was originally detected on v6.13-rc1 using our static analysis
tool, and we have verified that the issue persists in the latest mainline
kernel.
We performed build testing on x86_64 with allyesconfig using GCC=11.4.0.
Since triggering these error paths in xhci_disable_slot() requires specific
hardware conditions or abnormal state, we were unable to construct a test
case to reliably trigger these specific error paths at runtime.
CVSS Score
5.5
EPSS Score
0.0
Published
2026-05-08
In the Linux kernel, the following vulnerability has been resolved:
ceph: fix i_nlink underrun during async unlink
During async unlink, we drop the `i_nlink` counter before we receive
the completion (that will eventually update the `i_nlink`) because "we
assume that the unlink will succeed". That is not a bad idea, but it
races against deletions by other clients (or against the completion of
our own unlink) and can lead to an underrun which emits a WARNING like
this one:
WARNING: CPU: 85 PID: 25093 at fs/inode.c:407 drop_nlink+0x50/0x68
Modules linked in:
CPU: 85 UID: 3221252029 PID: 25093 Comm: php-cgi8.1 Not tainted 6.14.11-cm4all1-ampere #655
Hardware name: Supermicro ARS-110M-NR/R12SPD-A, BIOS 1.1b 10/17/2023
pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : drop_nlink+0x50/0x68
lr : ceph_unlink+0x6c4/0x720
sp : ffff80012173bc90
x29: ffff80012173bc90 x28: ffff086d0a45aaf8 x27: ffff0871d0eb5680
x26: ffff087f2a64a718 x25: 0000020000000180 x24: 0000000061c88647
x23: 0000000000000002 x22: ffff07ff9236d800 x21: 0000000000001203
x20: ffff07ff9237b000 x19: ffff088b8296afc0 x18: 00000000f3c93365
x17: 0000000000070000 x16: ffff08faffcbdfe8 x15: ffff08faffcbdfec
x14: 0000000000000000 x13: 45445f65645f3037 x12: 34385f6369706f74
x11: 0000a2653104bb20 x10: ffffd85f26d73290 x9 : ffffd85f25664f94
x8 : 00000000000000c0 x7 : 0000000000000000 x6 : 0000000000000002
x5 : 0000000000000081 x4 : 0000000000000481 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff08727d3f91e8
Call trace:
drop_nlink+0x50/0x68 (P)
vfs_unlink+0xb0/0x2e8
do_unlinkat+0x204/0x288
__arm64_sys_unlinkat+0x3c/0x80
invoke_syscall.constprop.0+0x54/0xe8
do_el0_svc+0xa4/0xc8
el0_svc+0x18/0x58
el0t_64_sync_handler+0x104/0x130
el0t_64_sync+0x154/0x158
In ceph_unlink(), a call to ceph_mdsc_submit_request() submits the
CEPH_MDS_OP_UNLINK to the MDS, but does not wait for completion.
Meanwhile, between this call and the following drop_nlink() call, a
worker thread may process a CEPH_CAP_OP_IMPORT, CEPH_CAP_OP_GRANT or
just a CEPH_MSG_CLIENT_REPLY (the latter of which could be our own
completion). These will lead to a set_nlink() call, updating the
`i_nlink` counter to the value received from the MDS. If that new
`i_nlink` value happens to be zero, it is illegal to decrement it
further. But that is exactly what ceph_unlink() will do then.
The WARNING can be reproduced this way:
1. Force async unlink; only the async code path is affected. Having
no real clue about Ceph internals, I was unable to find out why the
MDS wouldn't give me the "Fxr" capabilities, so I patched
get_caps_for_async_unlink() to always succeed.
(Note that the WARNING dump above was found on an unpatched kernel,
without this kludge - this is not a theoretical bug.)
2. Add a sleep call after ceph_mdsc_submit_request() so the unlink
completion gets handled by a worker thread before drop_nlink() is
called. This guarantees that the `i_nlink` is already zero before
drop_nlink() runs.
The solution is to skip the counter decrement when it is already zero,
but doing so without a lock is still racy (TOCTOU). Since
ceph_fill_inode() and handle_cap_grant() both hold the
`ceph_inode_info.i_ceph_lock` spinlock while set_nlink() runs, this
seems like the proper lock to protect the `i_nlink` updates.
I found prior art in NFS and SMB (using `inode.i_lock`) and AFS (using
`afs_vnode.cb_lock`). All three have the zero check as well.
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