| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
functionfs: fix the open/removal races
ffs_epfile_open() can race with removal, ending up with file->private_data
pointing to freed object.
There is a total count of opened files on functionfs (both ep0 and
dynamic ones) and when it hits zero, dynamic files get removed.
Unfortunately, that removal can happen while another thread is
in ffs_epfile_open(), but has not incremented the count yet.
In that case open will succeed, leaving us with UAF on any subsequent
read() or write().
The root cause is that ffs->opened is misused; atomic_dec_and_test() vs.
atomic_add_return() is not a good idea, when object remains visible all
along.
To untangle that
* serialize openers on ffs->mutex (both for ep0 and for dynamic files)
* have dynamic ones use atomic_inc_not_zero() and fail if we had
zero ->opened; in that case the file we are opening is doomed.
* have the inodes of dynamic files marked on removal (from the
callback of simple_recursive_removal()) - clear ->i_private there.
* have open of dynamic ones verify they hadn't been already removed,
along with checking that state is FFS_ACTIVE. |
| In the Linux kernel, the following vulnerability has been resolved:
net/sched: ets: Always remove class from active list before deleting in ets_qdisc_change
zdi-disclosures@trendmicro.com says:
The vulnerability is a race condition between `ets_qdisc_dequeue` and
`ets_qdisc_change`. It leads to UAF on `struct Qdisc` object.
Attacker requires the capability to create new user and network namespace
in order to trigger the bug.
See my additional commentary at the end of the analysis.
Analysis:
static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt,
struct netlink_ext_ack *extack)
{
...
// (1) this lock is preventing .change handler (`ets_qdisc_change`)
//to race with .dequeue handler (`ets_qdisc_dequeue`)
sch_tree_lock(sch);
for (i = nbands; i < oldbands; i++) {
if (i >= q->nstrict && q->classes[i].qdisc->q.qlen)
list_del_init(&q->classes[i].alist);
qdisc_purge_queue(q->classes[i].qdisc);
}
WRITE_ONCE(q->nbands, nbands);
for (i = nstrict; i < q->nstrict; i++) {
if (q->classes[i].qdisc->q.qlen) {
// (2) the class is added to the q->active
list_add_tail(&q->classes[i].alist, &q->active);
q->classes[i].deficit = quanta[i];
}
}
WRITE_ONCE(q->nstrict, nstrict);
memcpy(q->prio2band, priomap, sizeof(priomap));
for (i = 0; i < q->nbands; i++)
WRITE_ONCE(q->classes[i].quantum, quanta[i]);
for (i = oldbands; i < q->nbands; i++) {
q->classes[i].qdisc = queues[i];
if (q->classes[i].qdisc != &noop_qdisc)
qdisc_hash_add(q->classes[i].qdisc, true);
}
// (3) the qdisc is unlocked, now dequeue can be called in parallel
// to the rest of .change handler
sch_tree_unlock(sch);
ets_offload_change(sch);
for (i = q->nbands; i < oldbands; i++) {
// (4) we're reducing the refcount for our class's qdisc and
// freeing it
qdisc_put(q->classes[i].qdisc);
// (5) If we call .dequeue between (4) and (5), we will have
// a strong UAF and we can control RIP
q->classes[i].qdisc = NULL;
WRITE_ONCE(q->classes[i].quantum, 0);
q->classes[i].deficit = 0;
gnet_stats_basic_sync_init(&q->classes[i].bstats);
memset(&q->classes[i].qstats, 0, sizeof(q->classes[i].qstats));
}
return 0;
}
Comment:
This happens because some of the classes have their qdiscs assigned to
NULL, but remain in the active list. This commit fixes this issue by always
removing the class from the active list before deleting and freeing its
associated qdisc
Reproducer Steps
(trimmed version of what was sent by zdi-disclosures@trendmicro.com)
```
DEV="${DEV:-lo}"
ROOT_HANDLE="${ROOT_HANDLE:-1:}"
BAND2_HANDLE="${BAND2_HANDLE:-20:}" # child under 1:2
PING_BYTES="${PING_BYTES:-48}"
PING_COUNT="${PING_COUNT:-200000}"
PING_DST="${PING_DST:-127.0.0.1}"
SLOW_TBF_RATE="${SLOW_TBF_RATE:-8bit}"
SLOW_TBF_BURST="${SLOW_TBF_BURST:-100b}"
SLOW_TBF_LAT="${SLOW_TBF_LAT:-1s}"
cleanup() {
tc qdisc del dev "$DEV" root 2>/dev/null
}
trap cleanup EXIT
ip link set "$DEV" up
tc qdisc del dev "$DEV" root 2>/dev/null || true
tc qdisc add dev "$DEV" root handle "$ROOT_HANDLE" ets bands 2 strict 2
tc qdisc add dev "$DEV" parent 1:2 handle "$BAND2_HANDLE" \
tbf rate "$SLOW_TBF_RATE" burst "$SLOW_TBF_BURST" latency "$SLOW_TBF_LAT"
tc filter add dev "$DEV" parent 1: protocol all prio 1 u32 match u32 0 0 flowid 1:2
tc -s qdisc ls dev $DEV
ping -I "$DEV" -f -c "$PING_COUNT" -s "$PING_BYTES" -W 0.001 "$PING_DST" \
>/dev/null 2>&1 &
tc qdisc change dev "$DEV" root handle "$ROOT_HANDLE" ets bands 2 strict 0
tc qdisc change dev "$DEV" root handle "$ROOT_HANDLE" ets bands 2 strict 2
tc -s qdisc ls dev $DEV
tc qdisc del dev "$DEV" parent
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
accel/ivpu: Fix race condition when unbinding BOs
Fix 'Memory manager not clean during takedown' warning that occurs
when ivpu_gem_bo_free() removes the BO from the BOs list before it
gets unmapped. Then file_priv_unbind() triggers a warning in
drm_mm_takedown() during context teardown.
Protect the unmapping sequence with bo_list_lock to ensure the BO is
always fully unmapped when removed from the list. This ensures the BO
is either fully unmapped at context teardown time or present on the
list and unmapped by file_priv_unbind(). |
| In the Linux kernel, the following vulnerability has been resolved:
ksmbd: Fix race condition in RPC handle list access
The 'sess->rpc_handle_list' XArray manages RPC handles within a ksmbd
session. Access to this list is intended to be protected by
'sess->rpc_lock' (an rw_semaphore). However, the locking implementation was
flawed, leading to potential race conditions.
In ksmbd_session_rpc_open(), the code incorrectly acquired only a read lock
before calling xa_store() and xa_erase(). Since these operations modify
the XArray structure, a write lock is required to ensure exclusive access
and prevent data corruption from concurrent modifications.
Furthermore, ksmbd_session_rpc_method() accessed the list using xa_load()
without holding any lock at all. This could lead to reading inconsistent
data or a potential use-after-free if an entry is concurrently removed and
the pointer is dereferenced.
Fix these issues by:
1. Using down_write() and up_write() in ksmbd_session_rpc_open()
to ensure exclusive access during XArray modification, and ensuring
the lock is correctly released on error paths.
2. Adding down_read() and up_read() in ksmbd_session_rpc_method()
to safely protect the lookup. |
| In the Linux kernel, the following vulnerability has been resolved:
iommufd: Fix race during abort for file descriptors
fput() doesn't actually call file_operations release() synchronously, it
puts the file on a work queue and it will be released eventually.
This is normally fine, except for iommufd the file and the iommufd_object
are tied to gether. The file has the object as it's private_data and holds
a users refcount, while the object is expected to remain alive as long as
the file is.
When the allocation of a new object aborts before installing the file it
will fput() the file and then go on to immediately kfree() the obj. This
causes a UAF once the workqueue completes the fput() and tries to
decrement the users refcount.
Fix this by putting the core code in charge of the file lifetime, and call
__fput_sync() during abort to ensure that release() is called before
kfree. __fput_sync() is a bit too tricky to open code in all the object
implementations. Instead the objects tell the core code where the file
pointer is and the core will take care of the life cycle.
If the object is successfully allocated then the file will hold a users
refcount and the iommufd_object cannot be destroyed.
It is worth noting that close(); ioctl(IOMMU_DESTROY); doesn't have an
issue because close() is already using a synchronous version of fput().
The UAF looks like this:
BUG: KASAN: slab-use-after-free in iommufd_eventq_fops_release+0x45/0xc0 drivers/iommu/iommufd/eventq.c:376
Write of size 4 at addr ffff888059c97804 by task syz.0.46/6164
CPU: 0 UID: 0 PID: 6164 Comm: syz.0.46 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0xcd/0x630 mm/kasan/report.c:482
kasan_report+0xe0/0x110 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x100/0x1b0 mm/kasan/generic.c:189
instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
atomic_fetch_sub_release include/linux/atomic/atomic-instrumented.h:400 [inline]
__refcount_dec include/linux/refcount.h:455 [inline]
refcount_dec include/linux/refcount.h:476 [inline]
iommufd_eventq_fops_release+0x45/0xc0 drivers/iommu/iommufd/eventq.c:376
__fput+0x402/0xb70 fs/file_table.c:468
task_work_run+0x14d/0x240 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
do_syscall_64+0x41c/0x4c0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f |
| In the Linux kernel, the following vulnerability has been resolved:
iommu/amd/pgtbl: Fix possible race while increase page table level
The AMD IOMMU host page table implementation supports dynamic page table levels
(up to 6 levels), starting with a 3-level configuration that expands based on
IOVA address. The kernel maintains a root pointer and current page table level
to enable proper page table walks in alloc_pte()/fetch_pte() operations.
The IOMMU IOVA allocator initially starts with 32-bit address and onces its
exhuasted it switches to 64-bit address (max address is determined based
on IOMMU and device DMA capability). To support larger IOVA, AMD IOMMU
driver increases page table level.
But in unmap path (iommu_v1_unmap_pages()), fetch_pte() reads
pgtable->[root/mode] without lock. So its possible that in exteme corner case,
when increase_address_space() is updating pgtable->[root/mode], fetch_pte()
reads wrong page table level (pgtable->mode). It does compare the value with
level encoded in page table and returns NULL. This will result is
iommu_unmap ops to fail and upper layer may retry/log WARN_ON.
CPU 0 CPU 1
------ ------
map pages unmap pages
alloc_pte() -> increase_address_space() iommu_v1_unmap_pages() -> fetch_pte()
pgtable->root = pte (new root value)
READ pgtable->[mode/root]
Reads new root, old mode
Updates mode (pgtable->mode += 1)
Since Page table level updates are infrequent and already synchronized with a
spinlock, implement seqcount to enable lock-free read operations on the read path. |
| In the Linux kernel, the following vulnerability has been resolved:
zram: fix slot write race condition
Parallel concurrent writes to the same zram index result in leaked
zsmalloc handles. Schematically we can have something like this:
CPU0 CPU1
zram_slot_lock()
zs_free(handle)
zram_slot_lock()
zram_slot_lock()
zs_free(handle)
zram_slot_lock()
compress compress
handle = zs_malloc() handle = zs_malloc()
zram_slot_lock
zram_set_handle(handle)
zram_slot_lock
zram_slot_lock
zram_set_handle(handle)
zram_slot_lock
Either CPU0 or CPU1 zsmalloc handle will leak because zs_free() is done
too early. In fact, we need to reset zram entry right before we set its
new handle, all under the same slot lock scope. |
| In the Linux kernel, the following vulnerability has been resolved:
ceph: fix race condition validating r_parent before applying state
Add validation to ensure the cached parent directory inode matches the
directory info in MDS replies. This prevents client-side race conditions
where concurrent operations (e.g. rename) cause r_parent to become stale
between request initiation and reply processing, which could lead to
applying state changes to incorrect directory inodes.
[ idryomov: folded a kerneldoc fixup and a follow-up fix from Alex to
move CEPH_CAP_PIN reference when r_parent is updated:
When the parent directory lock is not held, req->r_parent can become
stale and is updated to point to the correct inode. However, the
associated CEPH_CAP_PIN reference was not being adjusted. The
CEPH_CAP_PIN is a reference on an inode that is tracked for
accounting purposes. Moving this pin is important to keep the
accounting balanced. When the pin was not moved from the old parent
to the new one, it created two problems: The reference on the old,
stale parent was never released, causing a reference leak.
A reference for the new parent was never acquired, creating the risk
of a reference underflow later in ceph_mdsc_release_request(). This
patch corrects the logic by releasing the pin from the old parent and
acquiring it for the new parent when r_parent is switched. This
ensures reference accounting stays balanced. ] |
| In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix race with concurrent opens in rename(2)
Besides sending the rename request to the server, the rename process
also involves closing any deferred close, waiting for outstanding I/O
to complete as well as marking all existing open handles as deleted to
prevent them from deferring closes, which increases the race window
for potential concurrent opens on the target file.
Fix this by unhashing the dentry in advance to prevent any concurrent
opens on the target. |
| In the Linux kernel, the following vulnerability has been resolved:
s390/ism: fix concurrency management in ism_cmd()
The s390x ISM device data sheet clearly states that only one
request-response sequence is allowable per ISM function at any point in
time. Unfortunately as of today the s390/ism driver in Linux does not
honor that requirement. This patch aims to rectify that.
This problem was discovered based on Aliaksei's bug report which states
that for certain workloads the ISM functions end up entering error state
(with PEC 2 as seen from the logs) after a while and as a consequence
connections handled by the respective function break, and for future
connection requests the ISM device is not considered -- given it is in a
dysfunctional state. During further debugging PEC 3A was observed as
well.
A kernel message like
[ 1211.244319] zpci: 061a:00:00.0: Event 0x2 reports an error for PCI function 0x61a
is a reliable indicator of the stated function entering error state
with PEC 2. Let me also point out that a kernel message like
[ 1211.244325] zpci: 061a:00:00.0: The ism driver bound to the device does not support error recovery
is a reliable indicator that the ISM function won't be auto-recovered
because the ISM driver currently lacks support for it.
On a technical level, without this synchronization, commands (inputs to
the FW) may be partially or fully overwritten (corrupted) by another CPU
trying to issue commands on the same function. There is hard evidence that
this can lead to DMB token values being used as DMB IOVAs, leading to
PEC 2 PCI events indicating invalid DMA. But this is only one of the
failure modes imaginable. In theory even completely losing one command
and executing another one twice and then trying to interpret the outputs
as if the command we intended to execute was actually executed and not
the other one is also possible. Frankly, I don't feel confident about
providing an exhaustive list of possible consequences. |
| In the Linux kernel, the following vulnerability has been resolved:
NFS: Fix a race when updating an existing write
After nfs_lock_and_join_requests() tests for whether the request is
still attached to the mapping, nothing prevents a call to
nfs_inode_remove_request() from succeeding until we actually lock the
page group.
The reason is that whoever called nfs_inode_remove_request() doesn't
necessarily have a lock on the page group head.
So in order to avoid races, let's take the page group lock earlier in
nfs_lock_and_join_requests(), and hold it across the removal of the
request in nfs_inode_remove_request(). |
| In the Linux kernel, the following vulnerability has been resolved:
ppp: fix race conditions in ppp_fill_forward_path
ppp_fill_forward_path() has two race conditions:
1. The ppp->channels list can change between list_empty() and
list_first_entry(), as ppp_lock() is not held. If the only channel
is deleted in ppp_disconnect_channel(), list_first_entry() may
access an empty head or a freed entry, and trigger a panic.
2. pch->chan can be NULL. When ppp_unregister_channel() is called,
pch->chan is set to NULL before pch is removed from ppp->channels.
Fix these by using a lockless RCU approach:
- Use list_first_or_null_rcu() to safely test and access the first list
entry.
- Convert list modifications on ppp->channels to their RCU variants and
add synchronize_net() after removal.
- Check for a NULL pch->chan before dereferencing it. |
| In the Linux kernel, the following vulnerability has been resolved:
net: kcm: Fix race condition in kcm_unattach()
syzbot found a race condition when kcm_unattach(psock)
and kcm_release(kcm) are executed at the same time.
kcm_unattach() is missing a check of the flag
kcm->tx_stopped before calling queue_work().
If the kcm has a reserved psock, kcm_unattach() might get executed
between cancel_work_sync() and unreserve_psock() in kcm_release(),
requeuing kcm->tx_work right before kcm gets freed in kcm_done().
Remove kcm->tx_stopped and replace it by the less
error-prone disable_work_sync(). |
| In the Linux kernel, the following vulnerability has been resolved:
comedi: fix race between polling and detaching
syzbot reports a use-after-free in comedi in the below link, which is
due to comedi gladly removing the allocated async area even though poll
requests are still active on the wait_queue_head inside of it. This can
cause a use-after-free when the poll entries are later triggered or
removed, as the memory for the wait_queue_head has been freed. We need
to check there are no tasks queued on any of the subdevices' wait queues
before allowing the device to be detached by the `COMEDI_DEVCONFIG`
ioctl.
Tasks will read-lock `dev->attach_lock` before adding themselves to the
subdevice wait queue, so fix the problem in the `COMEDI_DEVCONFIG` ioctl
handler by write-locking `dev->attach_lock` before checking that all of
the subdevices are safe to be deleted. This includes testing for any
sleepers on the subdevices' wait queues. It remains locked until the
device has been detached. This requires the `comedi_device_detach()`
function to be refactored slightly, moving the bulk of it into new
function `comedi_device_detach_locked()`.
Note that the refactor of `comedi_device_detach()` results in
`comedi_device_cancel_all()` now being called while `dev->attach_lock`
is write-locked, which wasn't the case previously, but that does not
matter.
Thanks to Jens Axboe for diagnosing the problem and co-developing this
patch. |
| In the Linux kernel, the following vulnerability has been resolved:
xfrm: state: initialize state_ptrs earlier in xfrm_state_find
In case of preemption, xfrm_state_look_at will find a different
pcpu_id and look up states for that other CPU. If we matched a state
for CPU2 in the state_cache while the lookup started on CPU1, we will
jump to "found", but the "best" state that we got will be ignored and
we will enter the "acquire" block. This block uses state_ptrs, which
isn't initialized at this point.
Let's initialize state_ptrs just after taking rcu_read_lock. This will
also prevent a possible misuse in the future, if someone adjusts this
function. |
| In the Linux kernel, the following vulnerability has been resolved:
net/packet: fix a race in packet_set_ring() and packet_notifier()
When packet_set_ring() releases po->bind_lock, another thread can
run packet_notifier() and process an NETDEV_UP event.
This race and the fix are both similar to that of commit 15fe076edea7
("net/packet: fix a race in packet_bind() and packet_notifier()").
There too the packet_notifier NETDEV_UP event managed to run while a
po->bind_lock critical section had to be temporarily released. And
the fix was similarly to temporarily set po->num to zero to keep
the socket unhooked until the lock is retaken.
The po->bind_lock in packet_set_ring and packet_notifier precede the
introduction of git history. |
| In the Linux kernel, the following vulnerability has been resolved:
tls: handle data disappearing from under the TLS ULP
TLS expects that it owns the receive queue of the TCP socket.
This cannot be guaranteed in case the reader of the TCP socket
entered before the TLS ULP was installed, or uses some non-standard
read API (eg. zerocopy ones). Replace the WARN_ON() and a buggy
early exit (which leaves anchor pointing to a freed skb) with real
error handling. Wipe the parsing state and tell the reader to retry.
We already reload the anchor every time we (re)acquire the socket lock,
so the only condition we need to avoid is an out of bounds read
(not having enough bytes in the socket for previously parsed record len).
If some data was read from under TLS but there's enough in the queue
we'll reload and decrypt what is most likely not a valid TLS record.
Leading to some undefined behavior from TLS perspective (corrupting
a stream? missing an alert? missing an attack?) but no kernel crash
should take place. |
| In the Linux kernel, the following vulnerability has been resolved:
ksmbd: fix Preauh_HashValue race condition
If client send multiple session setup requests to ksmbd,
Preauh_HashValue race condition could happen.
There is no need to free sess->Preauh_HashValue at session setup phase.
It can be freed together with session at connection termination phase. |
| In the Linux kernel, the following vulnerability has been resolved:
rxrpc: Fix recv-recv race of completed call
If a call receives an event (such as incoming data), the call gets placed
on the socket's queue and a thread in recvmsg can be awakened to go and
process it. Once the thread has picked up the call off of the queue,
further events will cause it to be requeued, and once the socket lock is
dropped (recvmsg uses call->user_mutex to allow the socket to be used in
parallel), a second thread can come in and its recvmsg can pop the call off
the socket queue again.
In such a case, the first thread will be receiving stuff from the call and
the second thread will be blocked on call->user_mutex. The first thread
can, at this point, process both the event that it picked call for and the
event that the second thread picked the call for and may see the call
terminate - in which case the call will be "released", decoupling the call
from the user call ID assigned to it (RXRPC_USER_CALL_ID in the control
message).
The first thread will return okay, but then the second thread will wake up
holding the user_mutex and, if it sees that the call has been released by
the first thread, it will BUG thusly:
kernel BUG at net/rxrpc/recvmsg.c:474!
Fix this by just dequeuing the call and ignoring it if it is seen to be
already released. We can't tell userspace about it anyway as the user call
ID has become stale. |
| In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_qfq: Fix race condition on qfq_aggregate
A race condition can occur when 'agg' is modified in qfq_change_agg
(called during qfq_enqueue) while other threads access it
concurrently. For example, qfq_dump_class may trigger a NULL
dereference, and qfq_delete_class may cause a use-after-free.
This patch addresses the issue by:
1. Moved qfq_destroy_class into the critical section.
2. Added sch_tree_lock protection to qfq_dump_class and
qfq_dump_class_stats. |
