Linux: >> Linux Kernel >> 6.6.158 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
nvdimm: pmem: keep PREFLUSH before data writes
pmem_submit_bio() records a REQ_PREFLUSH error, but continues to copy the
bio data and can later overwrite the error with a successful REQ_FUA flush.
That lets data writes run after a failed preflush and can complete the bio
successfully despite the failed ordering barrier.
Run the REQ_PREFLUSH flush synchronously before touching the bio data and
complete the bio with the flush error if it fails. Keep asynchronous flush
chaining for REQ_FUA. At that point, data copy has completed and the parent
bio can wait for the chained flush bio.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-09-25
In the Linux kernel, the following vulnerability has been resolved:
smb/server: fix tree connection leak in smb2_tree_connect()
See the procedure below:
smb2_tree_connect
ksmbd_tree_conn_connect
xa_store(&sess->tree_conns, tree_conn->id, tree_conn)
ksmbd_counter_inc(KSMBD_COUNTER_TREE_CONNS)
ksmbd_share_tree_conn_inc(sc)
ksmbd_iov_pin_rsp // fail
status.ret = KSMBD_TREE_CONN_STATUS_NOMEM
// do not disconnect tree_conn
Disconnect the new tree connection if ksmbd_iov_pin_rsp() fails.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-09-25
In the Linux kernel, the following vulnerability has been resolved:
staging: rtl8723bs: fix xmit_frame/xmit_buf leaks on mgnt-frame error paths
issue_beacon(), issue_probersp() and issue_asocrsp() obtain a management
xmit_frame together with its xmit_buf from the driver's fixed-size
management-TX pools via alloc_mgtxmitframe(). On the normal path the frame
is handed to dump_mgntframe(), which transfers ownership and eventually
returns both objects to their pools (the frame and, for beacons, the buf
in rtl8723bs_mgnt_xmit(); other bufs via the pending-xmitbuf/TX-completion
path).
Several error/edge paths return early after a successful
alloc_mgtxmitframe() but before dump_mgntframe(), so ownership is never
transferred and neither object is freed:
- issue_beacon(): beacon larger than 512 bytes
- issue_probersp(): cur_network->ie_length > MAX_IE_SZ
- issue_probersp(): kzalloc() of the SSID scratch buffer fails
- issue_asocrsp(): pkt_type is neither ASSOCRSP nor REASSOCRSP
Because alloc_mgtxmitframe() removes the frame and buf from their free
lists (list_del_init) without placing them on any pending list, an
orphaned pair is on no list and referenced by nobody, so it is only
reclaimed at driver teardown. Repeated hits progressively exhaust the
management-TX pools until alloc_mgtxmitframe() returns NULL and the
interface can no longer send beacons or probe/assoc responses.
Free the frame and buffer on these paths, matching the existing correct
error handling in issue_assocreq().
CVSS Score
5.5
EPSS Score
0.001
Published
2026-09-25
In the Linux kernel, the following vulnerability has been resolved:
drm/msm: Recover HW before retire hung submit
During recovery, it is not safe to retire the hung submit before we
recover the GPU. Retiring the submit triggers BO free and that can
result in GPU pagefaults since the GPU may be actively accessing those
BOs.
To fix this, retire the submits after gpu recovery is complete in
recover_worker().
Patchwork: https://patchwork.freedesktop.org/patch/730655/
CVSS Score
5.5
EPSS Score
0.001
Published
2026-09-25
In the Linux kernel, the following vulnerability has been resolved:
bpf: Mark bpf_refcount field as unique
BPF_REFCOUNT is not marked as a unique field, while it should be. Fix
this oversight.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-09-25
In the Linux kernel, the following vulnerability has been resolved:
drm/virtio: use the DMA API for resource backing on Xen
On a Xen PV domain page addresses bear no relation to the real machine
addresses the host would have to use to reach it.
virtio_ring.c handles this correctly, vring_use_map_api() returns true
for any xen_domain() regardless of VIRTIO_F_ACCESS_PLATFORM.
virtio-gpu makes the same decision independently, but its copy
looks only at the feature bit:
bool use_dma_api = !virtio_has_dma_quirk(vgdev->vdev);
QEMU does not set iommu_platform on virtio-vga by default, so
VIRTIO_F_ACCESS_PLATFORM is not negotiated, use_dma_api is false, and
virtio_gpu_object_shmem_init() describes the framebuffer's backing pages
to the host with sg_phys(). Those are guest-physical addresses. In a PV
domain they resolve, on the host side, to pages belonging to some other
domain, so the host scans out unrelated memory.
Move the decision into virtio_gpu_use_dma_api() and give it the
xen_domain() check, like vring_use_map_api() has. This
additionally enables the dma_sync_sgtable_for_device() calls in
virtgpu_vq.c, which are required for correctness whenever swiotlb
is in play.
Reproduced with a Xen 4.21 PV dom0 nested inside QEMU 8.2 with
virtio-vga, on both a distro 6.8 kernel and 6.18 LTS. A PVH dom0
works fine and doesn't need this fix because it is identity-mapped,
only PV dom0s are affected.
CVSS Score
7.8
EPSS Score
0.001
Published
2026-09-25
In the Linux kernel, the following vulnerability has been resolved:
net: stmmac: fix dma mapping leak in stmmac_tso_xmit()
In stmmac_tso_xmit(), if the DMA mapping of an skb fragment fails, the
frame is dropped but the DMA mappings already created for the linear
part and for the fragments mapped before the failure are never
unmapped, leaking DMA mappings.
Fix the leak by walking back over the descriptors used by the frame and
releasing each of them with stmmac_free_tx_buffer(). Moreover, release
the descriptors with stmmac_release_tx_desc() unmapping the DMA buffers.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-09-25
In the Linux kernel, the following vulnerability has been resolved:
bpf: check_cond_jmp_op(): properly infer if register is null
Nicholas Carlini reported a bug when verifier can incorrectly infer
that a pointer is non-null. The bug occurs when two pointers are
compared and one of them has a type w/o PTR_MAYBE_NULL flag,
but which allows a value to be NULL at runtime.
Here is an example:
// `a` is PTR_TO_MEM | MEM_RDONLY | PTR_UNTRUSTED
// `a` is 0 at runtime.
// `b` is PTR_TO_MAP_VALUE | PTR_MAYBE_NULL
void *a = bpf_rdonly_cast(0, 0);
int *b = bpf_map_lookup_elem(...);
if (a == b)
*b = 42; // verifier does not catch null pointer dereference
This happens because of a special case in check_cond_jmp_op(),
which attempts to strip PTR_MAYBE_NULL flags from pointer types,
when processing comparisons like `rA == rB`, if either rA or rB can't
be null.
The non-null property is derived based on the absence of
PTR_MAYBE_NULL flag on rA's or rB's type. But that is not sufficient
for types like PTR_TO_MEM, as in the example.
This patch replaces type_may_be_null() call with reg_not_null(),
which contains an allowlist of types for which absence of
PTR_MAYBE_NULL actually means that the value can't be NULL at runtime.
At the moment, the list in the reg_not_null() omits two types for
which PTR_MAYBE_NULL is applicable: PTR_TO_XDP_SOCK and PTR_TO_BUF.
In order to remain backward compatible, and assuming that only
comparison between pointers of the same type makes sense,
this commit extends reg_not_null(). W/o such an extension e.g.
verifier_jeq_infer_not_null/null_ptr_to_map_value fails.
reg_not_null() can be extended further, but I deem that out of scope
for the fix at hand. Explicit base_type(...) != PTR_TO_BTF_ID
checks in the check_cond_jmp_op() can be removed with migration to
reg_not_null(), but that is a behavioural change, as the special case
would start matching for PTR_TO_BTF_ID that is also is_trusted_reg().
I omit the behavioural change from this commit.
CVSS Score
5.5
EPSS Score
0.001
Published
2026-09-25
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: safely drain sessions during logoff
SMB3 multichannel allows requests for one session to run on multiple
connections. Wait for all channels bound to a session before freeing
shared session objects.
A deferred byte-range lock remains counted as a running request and only
wakes when its file closes. Wake blocked locks during the drain without
unpublishing or modifying their file objects. Synchronous CANCEL requests
must invoke their cancellation callback to wake pending operations, while
CHANGE_NOTIFY completion remains specific to the asynchronous path.
Serialize session teardown with channel registration and previous-session
cleanup, and use atomic work-state transitions so LOGOFF, CANCEL, and
connection teardown invoke cancellation callbacks only once.
CVSS Score
8.8
EPSS Score
0.003
Published
2026-09-25
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_core: Fix race condition during device registration
In hci_register_dev(), the power_on work item is queued to
hdev->req_workqueue before initializing hdev->adv_monitors_idr and
registering the MSFT extension via msft_register(). For devices marked with
quirks such as HCI_QUIRK_RAW_DEVICE, the HCI_UNCONFIGURED flag is set on
the device. When the power_on work item runs concurrently on another CPU,
hci_power_on() detects that the device is unconfigured and immediately
invokes hci_dev_do_close(), which calls msft_do_close().
Concurrently, msft_register() allocates the msft structure and exposes it
to hdev->msft_data prior to calling mutex_init(&msft->filter_lock). If
msft_do_close() executes while hdev->msft_data is already assigned but the
mutex has not yet been initialized, mutex_lock(&msft->filter_lock) operates
on an uninitialized mutex, triggering a DEBUG_LOCKS warning:
DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: kernel/locking/mutex.c:625 at __mutex_lock_common
kernel/locking/mutex.c:625 [inline]
WARNING: kernel/locking/mutex.c:625 at __mutex_lock+0x12d8/0x1550
kernel/locking/mutex.c:821
...
Call Trace:
<TASK>
msft_do_close+0x308/0x7b0 net/bluetooth/msft.c:693
hci_dev_close_sync+0x86b/0x10a0 net/bluetooth/hci_sync.c:5522
hci_dev_do_close net/bluetooth/hci_core.c:499 [inline]
hci_power_on+0x32c/0x750 net/bluetooth/hci_core.c:937
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0x92d/0xe10 kernel/workqueue.c:3486
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Fix this by moving the queue_work() call in hci_register_dev() to after
idr_init(&hdev->adv_monitors_idr) and msft_register(hdev) so that device
structures and extensions are fully initialized before asynchronous tasks
can access them. Additionally, assign hdev->msft_data in msft_register()
only after mutex_init(&msft->filter_lock) has completed.
CVSS Score
4.7
EPSS Score
0.001
Published
2026-09-25
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