Debian: Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
comedi: Fix initialization of data for instructions that write to subdevice
Some Comedi subdevice instruction handlers are known to access
instruction data elements beyond the first `insn->n` elements in some
cases. The `do_insn_ioctl()` and `do_insnlist_ioctl()` functions
allocate at least `MIN_SAMPLES` (16) data elements to deal with this,
but they do not initialize all of that. For Comedi instruction codes
that write to the subdevice, the first `insn->n` data elements are
copied from user-space, but the remaining elements are left
uninitialized. That could be a problem if the subdevice instruction
handler reads the uninitialized data. Ensure that the first
`MIN_SAMPLES` elements are initialized before calling these instruction
handlers, filling the uncopied elements with 0. For
`do_insnlist_ioctl()`, the same data buffer elements are used for
handling a list of instructions, so ensure the first `MIN_SAMPLES`
elements are initialized for each instruction that writes to the
subdevice.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-28
In the Linux kernel, the following vulnerability has been resolved:
net/sched: Return NULL when htb_lookup_leaf encounters an empty rbtree
htb_lookup_leaf has a BUG_ON that can trigger with the following:
tc qdisc del dev lo root
tc qdisc add dev lo root handle 1: htb default 1
tc class add dev lo parent 1: classid 1:1 htb rate 64bit
tc qdisc add dev lo parent 1:1 handle 2: netem
tc qdisc add dev lo parent 2:1 handle 3: blackhole
ping -I lo -c1 -W0.001 127.0.0.1
The root cause is the following:
1. htb_dequeue calls htb_dequeue_tree which calls the dequeue handler on
the selected leaf qdisc
2. netem_dequeue calls enqueue on the child qdisc
3. blackhole_enqueue drops the packet and returns a value that is not
just NET_XMIT_SUCCESS
4. Because of this, netem_dequeue calls qdisc_tree_reduce_backlog, and
since qlen is now 0, it calls htb_qlen_notify -> htb_deactivate ->
htb_deactiviate_prios -> htb_remove_class_from_row -> htb_safe_rb_erase
5. As this is the only class in the selected hprio rbtree,
__rb_change_child in __rb_erase_augmented sets the rb_root pointer to
NULL
6. Because blackhole_dequeue returns NULL, netem_dequeue returns NULL,
which causes htb_dequeue_tree to call htb_lookup_leaf with the same
hprio rbtree, and fail the BUG_ON
The function graph for this scenario is shown here:
0) | htb_enqueue() {
0) + 13.635 us | netem_enqueue();
0) 4.719 us | htb_activate_prios();
0) # 2249.199 us | }
0) | htb_dequeue() {
0) 2.355 us | htb_lookup_leaf();
0) | netem_dequeue() {
0) + 11.061 us | blackhole_enqueue();
0) | qdisc_tree_reduce_backlog() {
0) | qdisc_lookup_rcu() {
0) 1.873 us | qdisc_match_from_root();
0) 6.292 us | }
0) 1.894 us | htb_search();
0) | htb_qlen_notify() {
0) 2.655 us | htb_deactivate_prios();
0) 6.933 us | }
0) + 25.227 us | }
0) 1.983 us | blackhole_dequeue();
0) + 86.553 us | }
0) # 2932.761 us | qdisc_warn_nonwc();
0) | htb_lookup_leaf() {
0) | BUG_ON();
------------------------------------------
The full original bug report can be seen here [1].
We can fix this just by returning NULL instead of the BUG_ON,
as htb_dequeue_tree returns NULL when htb_lookup_leaf returns
NULL.
[1] https://lore.kernel.org/netdev/pF5XOOIim0IuEfhI-SOxTgRvNoDwuux7UHKnE_Y5-zVd4wmGvNk2ceHjKb8ORnzw0cGwfmVu42g9dL7XyJLf1NEzaztboTWcm0Ogxuojoeo=@willsroot.io/
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-28
In the Linux kernel, the following vulnerability has been resolved:
net: vlan: fix VLAN 0 refcount imbalance of toggling filtering during runtime
Assuming the "rx-vlan-filter" feature is enabled on a net device, the
8021q module will automatically add or remove VLAN 0 when the net device
is put administratively up or down, respectively. There are a couple of
problems with the above scheme.
The first problem is a memory leak that can happen if the "rx-vlan-filter"
feature is disabled while the device is running:
# ip link add bond1 up type bond mode 0
# ethtool -K bond1 rx-vlan-filter off
# ip link del dev bond1
When the device is put administratively down the "rx-vlan-filter"
feature is disabled, so the 8021q module will not remove VLAN 0 and the
memory will be leaked [1].
Another problem that can happen is that the kernel can automatically
delete VLAN 0 when the device is put administratively down despite not
adding it when the device was put administratively up since during that
time the "rx-vlan-filter" feature was disabled. null-ptr-unref or
bug_on[2] will be triggered by unregister_vlan_dev() for refcount
imbalance if toggling filtering during runtime:
$ ip link add bond0 type bond mode 0
$ ip link add link bond0 name vlan0 type vlan id 0 protocol 802.1q
$ ethtool -K bond0 rx-vlan-filter off
$ ifconfig bond0 up
$ ethtool -K bond0 rx-vlan-filter on
$ ifconfig bond0 down
$ ip link del vlan0
Root cause is as below:
step1: add vlan0 for real_dev, such as bond, team.
register_vlan_dev
vlan_vid_add(real_dev,htons(ETH_P_8021Q),0) //refcnt=1
step2: disable vlan filter feature and enable real_dev
step3: change filter from 0 to 1
vlan_device_event
vlan_filter_push_vids
ndo_vlan_rx_add_vid //No refcnt added to real_dev vlan0
step4: real_dev down
vlan_device_event
vlan_vid_del(dev, htons(ETH_P_8021Q), 0); //refcnt=0
vlan_info_rcu_free //free vlan0
step5: delete vlan0
unregister_vlan_dev
BUG_ON(!vlan_info); //vlan_info is null
Fix both problems by noting in the VLAN info whether VLAN 0 was
automatically added upon NETDEV_UP and based on that decide whether it
should be deleted upon NETDEV_DOWN, regardless of the state of the
"rx-vlan-filter" feature.
[1]
unreferenced object 0xffff8880068e3100 (size 256):
comm "ip", pid 384, jiffies 4296130254
hex dump (first 32 bytes):
00 20 30 0d 80 88 ff ff 00 00 00 00 00 00 00 00 . 0.............
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
backtrace (crc 81ce31fa):
__kmalloc_cache_noprof+0x2b5/0x340
vlan_vid_add+0x434/0x940
vlan_device_event.cold+0x75/0xa8
notifier_call_chain+0xca/0x150
__dev_notify_flags+0xe3/0x250
rtnl_configure_link+0x193/0x260
rtnl_newlink_create+0x383/0x8e0
__rtnl_newlink+0x22c/0xa40
rtnl_newlink+0x627/0xb00
rtnetlink_rcv_msg+0x6fb/0xb70
netlink_rcv_skb+0x11f/0x350
netlink_unicast+0x426/0x710
netlink_sendmsg+0x75a/0xc20
__sock_sendmsg+0xc1/0x150
____sys_sendmsg+0x5aa/0x7b0
___sys_sendmsg+0xfc/0x180
[2]
kernel BUG at net/8021q/vlan.c:99!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 382 Comm: ip Not tainted 6.16.0-rc3 #61 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014
RIP: 0010:unregister_vlan_dev (net/8021q/vlan.c:99 (discriminator 1))
RSP: 0018:ffff88810badf310 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88810da84000 RCX: ffffffffb47ceb9a
RDX: dffffc0000000000 RSI: 0000000000000008 RDI: ffff88810e8b43c8
RBP: 0000000000000000 R08: 0000000000000000 R09: fffffbfff6cefe80
R10: ffffffffb677f407 R11: ffff88810badf3c0 R12: ffff88810e8b4000
R13: 0000000000000000 R14: ffff88810642a5c0 R15: 000000000000017e
FS: 00007f1ff68c20c0(0000) GS:ffff888163a24000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1ff5dad240 CR3: 0000000107e56000 CR4: 00000000000006f0
Call Trace:
<TASK
---truncated---
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-28
In the Linux kernel, the following vulnerability has been resolved:
tls: always refresh the queue when reading sock
After recent changes in net-next TCP compacts skbs much more
aggressively. This unearthed a bug in TLS where we may try
to operate on an old skb when checking if all skbs in the
queue have matching decrypt state and geometry.
BUG: KASAN: slab-use-after-free in tls_strp_check_rcv+0x898/0x9a0 [tls]
(net/tls/tls_strp.c:436 net/tls/tls_strp.c:530 net/tls/tls_strp.c:544)
Read of size 4 at addr ffff888013085750 by task tls/13529
CPU: 2 UID: 0 PID: 13529 Comm: tls Not tainted 6.16.0-rc5-virtme
Call Trace:
kasan_report+0xca/0x100
tls_strp_check_rcv+0x898/0x9a0 [tls]
tls_rx_rec_wait+0x2c9/0x8d0 [tls]
tls_sw_recvmsg+0x40f/0x1aa0 [tls]
inet_recvmsg+0x1c3/0x1f0
Always reload the queue, fast path is to have the record in the queue
when we wake, anyway (IOW the path going down "if !strp->stm.full_len").
CVSS Score
7.8
EPSS Score
0.0
Published
2025-07-28
In the Linux kernel, the following vulnerability has been resolved:
drm/exynos: exynos7_drm_decon: add vblank check in IRQ handling
If there's support for another console device (such as a TTY serial),
the kernel occasionally panics during boot. The panic message and a
relevant snippet of the call stack is as follows:
Unable to handle kernel NULL pointer dereference at virtual address 000000000000000
Call trace:
drm_crtc_handle_vblank+0x10/0x30 (P)
decon_irq_handler+0x88/0xb4
[...]
Otherwise, the panics don't happen. This indicates that it's some sort
of race condition.
Add a check to validate if the drm device can handle vblanks before
calling drm_crtc_handle_vblank() to avoid this.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-25
In the Linux kernel, the following vulnerability has been resolved:
vsock: Fix transport_{g2h,h2g} TOCTOU
vsock_find_cid() and vsock_dev_do_ioctl() may race with module unload.
transport_{g2h,h2g} may become NULL after the NULL check.
Introduce vsock_transport_local_cid() to protect from a potential
null-ptr-deref.
KASAN: null-ptr-deref in range [0x0000000000000118-0x000000000000011f]
RIP: 0010:vsock_find_cid+0x47/0x90
Call Trace:
__vsock_bind+0x4b2/0x720
vsock_bind+0x90/0xe0
__sys_bind+0x14d/0x1e0
__x64_sys_bind+0x6e/0xc0
do_syscall_64+0x92/0x1c0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
KASAN: null-ptr-deref in range [0x0000000000000118-0x000000000000011f]
RIP: 0010:vsock_dev_do_ioctl.isra.0+0x58/0xf0
Call Trace:
__x64_sys_ioctl+0x12d/0x190
do_syscall_64+0x92/0x1c0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
CVSS Score
4.7
EPSS Score
0.0
Published
2025-07-25
In the Linux kernel, the following vulnerability has been resolved:
tipc: Fix use-after-free in tipc_conn_close().
syzbot reported a null-ptr-deref in tipc_conn_close() during netns
dismantle. [0]
tipc_topsrv_stop() iterates tipc_net(net)->topsrv->conn_idr and calls
tipc_conn_close() for each tipc_conn.
The problem is that tipc_conn_close() is called after releasing the
IDR lock.
At the same time, there might be tipc_conn_recv_work() running and it
could call tipc_conn_close() for the same tipc_conn and release its
last ->kref.
Once we release the IDR lock in tipc_topsrv_stop(), there is no
guarantee that the tipc_conn is alive.
Let's hold the ref before releasing the lock and put the ref after
tipc_conn_close() in tipc_topsrv_stop().
[0]:
BUG: KASAN: use-after-free in tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165
Read of size 8 at addr ffff888099305a08 by task kworker/u4:3/435
CPU: 0 PID: 435 Comm: kworker/u4:3 Not tainted 4.19.204-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1fc/0x2ef lib/dump_stack.c:118
print_address_description.cold+0x54/0x219 mm/kasan/report.c:256
kasan_report_error.cold+0x8a/0x1b9 mm/kasan/report.c:354
kasan_report mm/kasan/report.c:412 [inline]
__asan_report_load8_noabort+0x88/0x90 mm/kasan/report.c:433
tipc_conn_close+0x122/0x140 net/tipc/topsrv.c:165
tipc_topsrv_stop net/tipc/topsrv.c:701 [inline]
tipc_topsrv_exit_net+0x27b/0x5c0 net/tipc/topsrv.c:722
ops_exit_list+0xa5/0x150 net/core/net_namespace.c:153
cleanup_net+0x3b4/0x8b0 net/core/net_namespace.c:553
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Allocated by task 23:
kmem_cache_alloc_trace+0x12f/0x380 mm/slab.c:3625
kmalloc include/linux/slab.h:515 [inline]
kzalloc include/linux/slab.h:709 [inline]
tipc_conn_alloc+0x43/0x4f0 net/tipc/topsrv.c:192
tipc_topsrv_accept+0x1b5/0x280 net/tipc/topsrv.c:470
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Freed by task 23:
__cache_free mm/slab.c:3503 [inline]
kfree+0xcc/0x210 mm/slab.c:3822
tipc_conn_kref_release net/tipc/topsrv.c:150 [inline]
kref_put include/linux/kref.h:70 [inline]
conn_put+0x2cd/0x3a0 net/tipc/topsrv.c:155
process_one_work+0x864/0x1570 kernel/workqueue.c:2153
worker_thread+0x64c/0x1130 kernel/workqueue.c:2296
kthread+0x33f/0x460 kernel/kthread.c:259
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
The buggy address belongs to the object at ffff888099305a00
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 8 bytes inside of
512-byte region [ffff888099305a00, ffff888099305c00)
The buggy address belongs to the page:
page:ffffea000264c140 count:1 mapcount:0 mapping:ffff88813bff0940 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffffea00028b6b88 ffffea0002cd2b08 ffff88813bff0940
raw: 0000000000000000 ffff888099305000 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff888099305900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888099305980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888099305a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888099305a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888099305b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
CVSS Score
7.8
EPSS Score
0.0
Published
2025-07-25
In the Linux kernel, the following vulnerability has been resolved:
netlink: Fix wraparounds of sk->sk_rmem_alloc.
Netlink has this pattern in some places
if (atomic_read(&sk->sk_rmem_alloc) > sk->sk_rcvbuf)
atomic_add(skb->truesize, &sk->sk_rmem_alloc);
, which has the same problem fixed by commit 5a465a0da13e ("udp:
Fix multiple wraparounds of sk->sk_rmem_alloc.").
For example, if we set INT_MAX to SO_RCVBUFFORCE, the condition
is always false as the two operands are of int.
Then, a single socket can eat as many skb as possible until OOM
happens, and we can see multiple wraparounds of sk->sk_rmem_alloc.
Let's fix it by using atomic_add_return() and comparing the two
variables as unsigned int.
Before:
[root@fedora ~]# ss -f netlink
Recv-Q Send-Q Local Address:Port Peer Address:Port
-1668710080 0 rtnl:nl_wraparound/293 *
After:
[root@fedora ~]# ss -f netlink
Recv-Q Send-Q Local Address:Port Peer Address:Port
2147483072 0 rtnl:nl_wraparound/290 *
^
`--- INT_MAX - 576
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-25
In the Linux kernel, the following vulnerability has been resolved:
perf: Revert to requiring CAP_SYS_ADMIN for uprobes
Jann reports that uprobes can be used destructively when used in the
middle of an instruction. The kernel only verifies there is a valid
instruction at the requested offset, but due to variable instruction
length cannot determine if this is an instruction as seen by the
intended execution stream.
Additionally, Mark Rutland notes that on architectures that mix data
in the text segment (like arm64), a similar things can be done if the
data word is 'mistaken' for an instruction.
As such, require CAP_SYS_ADMIN for uprobes.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-25
In the Linux kernel, the following vulnerability has been resolved:
KVM: SVM: Reject SEV{-ES} intra host migration if vCPU creation is in-flight
Reject migration of SEV{-ES} state if either the source or destination VM
is actively creating a vCPU, i.e. if kvm_vm_ioctl_create_vcpu() is in the
section between incrementing created_vcpus and online_vcpus. The bulk of
vCPU creation runs _outside_ of kvm->lock to allow creating multiple vCPUs
in parallel, and so sev_info.es_active can get toggled from false=>true in
the destination VM after (or during) svm_vcpu_create(), resulting in an
SEV{-ES} VM effectively having a non-SEV{-ES} vCPU.
The issue manifests most visibly as a crash when trying to free a vCPU's
NULL VMSA page in an SEV-ES VM, but any number of things can go wrong.
BUG: unable to handle page fault for address: ffffebde00000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP KASAN NOPTI
CPU: 227 UID: 0 PID: 64063 Comm: syz.5.60023 Tainted: G U O 6.15.0-smp-DEV #2 NONE
Tainted: [U]=USER, [O]=OOT_MODULE
Hardware name: Google, Inc. Arcadia_IT_80/Arcadia_IT_80, BIOS 12.52.0-0 10/28/2024
RIP: 0010:constant_test_bit arch/x86/include/asm/bitops.h:206 [inline]
RIP: 0010:arch_test_bit arch/x86/include/asm/bitops.h:238 [inline]
RIP: 0010:_test_bit include/asm-generic/bitops/instrumented-non-atomic.h:142 [inline]
RIP: 0010:PageHead include/linux/page-flags.h:866 [inline]
RIP: 0010:___free_pages+0x3e/0x120 mm/page_alloc.c:5067
Code: <49> f7 06 40 00 00 00 75 05 45 31 ff eb 0c 66 90 4c 89 f0 4c 39 f0
RSP: 0018:ffff8984551978d0 EFLAGS: 00010246
RAX: 0000777f80000001 RBX: 0000000000000000 RCX: ffffffff918aeb98
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffebde00000000
RBP: 0000000000000000 R08: ffffebde00000007 R09: 1ffffd7bc0000000
R10: dffffc0000000000 R11: fffff97bc0000001 R12: dffffc0000000000
R13: ffff8983e19751a8 R14: ffffebde00000000 R15: 1ffffd7bc0000000
FS: 0000000000000000(0000) GS:ffff89ee661d3000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffebde00000000 CR3: 000000793ceaa000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000b5f DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
sev_free_vcpu+0x413/0x630 arch/x86/kvm/svm/sev.c:3169
svm_vcpu_free+0x13a/0x2a0 arch/x86/kvm/svm/svm.c:1515
kvm_arch_vcpu_destroy+0x6a/0x1d0 arch/x86/kvm/x86.c:12396
kvm_vcpu_destroy virt/kvm/kvm_main.c:470 [inline]
kvm_destroy_vcpus+0xd1/0x300 virt/kvm/kvm_main.c:490
kvm_arch_destroy_vm+0x636/0x820 arch/x86/kvm/x86.c:12895
kvm_put_kvm+0xb8e/0xfb0 virt/kvm/kvm_main.c:1310
kvm_vm_release+0x48/0x60 virt/kvm/kvm_main.c:1369
__fput+0x3e4/0x9e0 fs/file_table.c:465
task_work_run+0x1a9/0x220 kernel/task_work.c:227
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x7f0/0x25b0 kernel/exit.c:953
do_group_exit+0x203/0x2d0 kernel/exit.c:1102
get_signal+0x1357/0x1480 kernel/signal.c:3034
arch_do_signal_or_restart+0x40/0x690 arch/x86/kernel/signal.c:337
exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x67/0xb0 kernel/entry/common.c:218
do_syscall_64+0x7c/0x150 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f87a898e969
</TASK>
Modules linked in: gq(O)
gsmi: Log Shutdown Reason 0x03
CR2: ffffebde00000000
---[ end trace 0000000000000000 ]---
Deliberately don't check for a NULL VMSA when freeing the vCPU, as crashing
the host is likely desirable due to the VMSA being consumed by hardware.
E.g. if KVM manages to allow VMRUN on the vCPU, hardware may read/write a
bogus VMSA page. Accessing P
---truncated---
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-25