Linux: >> Linux Kernel >> 2.6.33.6 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:
comedi: Fix use of uninitialized data in insn_rw_emulate_bits()
For Comedi `INSN_READ` and `INSN_WRITE` instructions on "digital"
subdevices (subdevice types `COMEDI_SUBD_DI`, `COMEDI_SUBD_DO`, and
`COMEDI_SUBD_DIO`), it is common for the subdevice driver not to have
`insn_read` and `insn_write` handler functions, but to have an
`insn_bits` handler function for handling Comedi `INSN_BITS`
instructions. In that case, the subdevice's `insn_read` and/or
`insn_write` function handler pointers are set to point to the
`insn_rw_emulate_bits()` function by `__comedi_device_postconfig()`.
For `INSN_WRITE`, `insn_rw_emulate_bits()` currently assumes that the
supplied `data[0]` value is a valid copy from user memory. It will at
least exist because `do_insnlist_ioctl()` and `do_insn_ioctl()` in
"comedi_fops.c" ensure at lease `MIN_SAMPLES` (16) elements are
allocated. However, if `insn->n` is 0 (which is allowable for
`INSN_READ` and `INSN_WRITE` instructions, then `data[0]` may contain
uninitialized data, and certainly contains invalid data, possibly from a
different instruction in the array of instructions handled by
`do_insnlist_ioctl()`. This will result in an incorrect value being
written to the digital output channel (or to the digital input/output
channel if configured as an output), and may be reflected in the
internal saved state of the channel.
Fix it by returning 0 early if `insn->n` is 0, before reaching the code
that accesses `data[0]`. Previously, the function always returned 1 on
success, but it is supposed to be the number of data samples actually
read or written up to `insn->n`, which is 0 in this case.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-28
In the Linux kernel, the following vulnerability has been resolved:
comedi: Fail COMEDI_INSNLIST ioctl if n_insns is too large
The handling of the `COMEDI_INSNLIST` ioctl allocates a kernel buffer to
hold the array of `struct comedi_insn`, getting the length from the
`n_insns` member of the `struct comedi_insnlist` supplied by the user.
The allocation will fail with a WARNING and a stack dump if it is too
large.
Avoid that by failing with an `-EINVAL` error if the supplied `n_insns`
value is unreasonable.
Define the limit on the `n_insns` value in the `MAX_INSNS` macro. Set
this to the same value as `MAX_SAMPLES` (65536), which is the maximum
allowed sum of the values of the member `n` in the array of `struct
comedi_insn`, and sensible comedi instructions will have an `n` of at
least 1.
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:
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:
net/sched: Abort __tc_modify_qdisc if parent class does not exist
Lion's patch [1] revealed an ancient bug in the qdisc API.
Whenever a user creates/modifies a qdisc specifying as a parent another
qdisc, the qdisc API will, during grafting, detect that the user is
not trying to attach to a class and reject. However grafting is
performed after qdisc_create (and thus the qdiscs' init callback) is
executed. In qdiscs that eventually call qdisc_tree_reduce_backlog
during init or change (such as fq, hhf, choke, etc), an issue
arises. For example, executing the following commands:
sudo tc qdisc add dev lo root handle a: htb default 2
sudo tc qdisc add dev lo parent a: handle beef fq
Qdiscs such as fq, hhf, choke, etc unconditionally invoke
qdisc_tree_reduce_backlog() in their control path init() or change() which
then causes a failure to find the child class; however, that does not stop
the unconditional invocation of the assumed child qdisc's qlen_notify with
a null class. All these qdiscs make the assumption that class is non-null.
The solution is ensure that qdisc_leaf() which looks up the parent
class, and is invoked prior to qdisc_create(), should return failure on
not finding the class.
In this patch, we leverage qdisc_leaf to return ERR_PTRs whenever the
parentid doesn't correspond to a class, so that we can detect it
earlier on and abort before qdisc_create is called.
[1] https://lore.kernel.org/netdev/d912cbd7-193b-4269-9857-525bee8bbb6a@gmail.com/
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-25
In the Linux kernel, the following vulnerability has been resolved:
atm: clip: Fix NULL pointer dereference in vcc_sendmsg()
atmarpd_dev_ops does not implement the send method, which may cause crash
as bellow.
BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 0 P4D 0
Oops: Oops: 0010 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5324 Comm: syz.0.0 Not tainted 6.15.0-rc6-syzkaller-00346-g5723cc3450bc #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0018:ffffc9000d3cf778 EFLAGS: 00010246
RAX: 1ffffffff1910dd1 RBX: 00000000000000c0 RCX: dffffc0000000000
RDX: ffffc9000dc82000 RSI: ffff88803e4c4640 RDI: ffff888052cd0000
RBP: ffffc9000d3cf8d0 R08: ffff888052c9143f R09: 1ffff1100a592287
R10: dffffc0000000000 R11: 0000000000000000 R12: 1ffff92001a79f00
R13: ffff888052cd0000 R14: ffff88803e4c4640 R15: ffffffff8c886e88
FS: 00007fbc762566c0(0000) GS:ffff88808d6c2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 0000000041f1b000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
vcc_sendmsg+0xa10/0xc50 net/atm/common.c:644
sock_sendmsg_nosec net/socket.c:712 [inline]
__sock_sendmsg+0x219/0x270 net/socket.c:727
____sys_sendmsg+0x52d/0x830 net/socket.c:2566
___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620
__sys_sendmmsg+0x227/0x430 net/socket.c:2709
__do_sys_sendmmsg net/socket.c:2736 [inline]
__se_sys_sendmmsg net/socket.c:2733 [inline]
__x64_sys_sendmmsg+0xa0/0xc0 net/socket.c:2733
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-25
In the Linux kernel, the following vulnerability has been resolved:
atm: clip: Fix infinite recursive call of clip_push().
syzbot reported the splat below. [0]
This happens if we call ioctl(ATMARP_MKIP) more than once.
During the first call, clip_mkip() sets clip_push() to vcc->push(),
and the second call copies it to clip_vcc->old_push().
Later, when the socket is close()d, vcc_destroy_socket() passes
NULL skb to clip_push(), which calls clip_vcc->old_push(),
triggering the infinite recursion.
Let's prevent the second ioctl(ATMARP_MKIP) by checking
vcc->user_back, which is allocated by the first call as clip_vcc.
Note also that we use lock_sock() to prevent racy calls.
[0]:
BUG: TASK stack guard page was hit at ffffc9000d66fff8 (stack is ffffc9000d670000..ffffc9000d678000)
Oops: stack guard page: 0000 [#1] SMP KASAN NOPTI
CPU: 0 UID: 0 PID: 5322 Comm: syz.0.0 Not tainted 6.16.0-rc4-syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:clip_push+0x5/0x720 net/atm/clip.c:191
Code: e0 8f aa 8c e8 1c ad 5b fa eb ae 66 2e 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 20 48 89 f3 49 89 fd 48 bd 00
RSP: 0018:ffffc9000d670000 EFLAGS: 00010246
RAX: 1ffff1100235a4a5 RBX: ffff888011ad2508 RCX: ffff8880003c0000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888037f01000
RBP: dffffc0000000000 R08: ffffffff8fa104f7 R09: 1ffffffff1f4209e
R10: dffffc0000000000 R11: ffffffff8a99b300 R12: ffffffff8a99b300
R13: ffff888037f01000 R14: ffff888011ad2500 R15: ffff888037f01578
FS: 000055557ab6d500(0000) GS:ffff88808d250000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffc9000d66fff8 CR3: 0000000043172000 CR4: 0000000000352ef0
Call Trace:
<TASK>
clip_push+0x6dc/0x720 net/atm/clip.c:200
clip_push+0x6dc/0x720 net/atm/clip.c:200
clip_push+0x6dc/0x720 net/atm/clip.c:200
...
clip_push+0x6dc/0x720 net/atm/clip.c:200
clip_push+0x6dc/0x720 net/atm/clip.c:200
clip_push+0x6dc/0x720 net/atm/clip.c:200
vcc_destroy_socket net/atm/common.c:183 [inline]
vcc_release+0x157/0x460 net/atm/common.c:205
__sock_release net/socket.c:647 [inline]
sock_close+0xc0/0x240 net/socket.c:1391
__fput+0x449/0xa70 fs/file_table.c:465
task_work_run+0x1d1/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xec/0x110 kernel/entry/common.c:114
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff31c98e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffb5aa1f78 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 0000000000012747 RCX: 00007ff31c98e929
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007ff31cbb7ba0 R08: 0000000000000001 R09: 0000000db5aa226f
R10: 00007ff31c7ff030 R11: 0000000000000246 R12: 00007ff31cbb608c
R13: 00007ff31cbb6080 R14: ffffffffffffffff R15: 00007fffb5aa2090
</TASK>
Modules linked in:
CVSS Score
7.8
EPSS Score
0.0
Published
2025-07-25
In the Linux kernel, the following vulnerability has been resolved:
atm: clip: Fix potential null-ptr-deref in to_atmarpd().
atmarpd is protected by RTNL since commit f3a0592b37b8 ("[ATM]: clip
causes unregister hang").
However, it is not enough because to_atmarpd() is called without RTNL,
especially clip_neigh_solicit() / neigh_ops->solicit() is unsleepable.
Also, there is no RTNL dependency around atmarpd.
Let's use a private mutex and RCU to protect access to atmarpd in
to_atmarpd().
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-25
In the Linux kernel, the following vulnerability has been resolved:
drm/gem: Acquire references on GEM handles for framebuffers
A GEM handle can be released while the GEM buffer object is attached
to a DRM framebuffer. This leads to the release of the dma-buf backing
the buffer object, if any. [1] Trying to use the framebuffer in further
mode-setting operations leads to a segmentation fault. Most easily
happens with driver that use shadow planes for vmap-ing the dma-buf
during a page flip. An example is shown below.
[ 156.791968] ------------[ cut here ]------------
[ 156.796830] WARNING: CPU: 2 PID: 2255 at drivers/dma-buf/dma-buf.c:1527 dma_buf_vmap+0x224/0x430
[...]
[ 156.942028] RIP: 0010:dma_buf_vmap+0x224/0x430
[ 157.043420] Call Trace:
[ 157.045898] <TASK>
[ 157.048030] ? show_trace_log_lvl+0x1af/0x2c0
[ 157.052436] ? show_trace_log_lvl+0x1af/0x2c0
[ 157.056836] ? show_trace_log_lvl+0x1af/0x2c0
[ 157.061253] ? drm_gem_shmem_vmap+0x74/0x710
[ 157.065567] ? dma_buf_vmap+0x224/0x430
[ 157.069446] ? __warn.cold+0x58/0xe4
[ 157.073061] ? dma_buf_vmap+0x224/0x430
[ 157.077111] ? report_bug+0x1dd/0x390
[ 157.080842] ? handle_bug+0x5e/0xa0
[ 157.084389] ? exc_invalid_op+0x14/0x50
[ 157.088291] ? asm_exc_invalid_op+0x16/0x20
[ 157.092548] ? dma_buf_vmap+0x224/0x430
[ 157.096663] ? dma_resv_get_singleton+0x6d/0x230
[ 157.101341] ? __pfx_dma_buf_vmap+0x10/0x10
[ 157.105588] ? __pfx_dma_resv_get_singleton+0x10/0x10
[ 157.110697] drm_gem_shmem_vmap+0x74/0x710
[ 157.114866] drm_gem_vmap+0xa9/0x1b0
[ 157.118763] drm_gem_vmap_unlocked+0x46/0xa0
[ 157.123086] drm_gem_fb_vmap+0xab/0x300
[ 157.126979] drm_atomic_helper_prepare_planes.part.0+0x487/0xb10
[ 157.133032] ? lockdep_init_map_type+0x19d/0x880
[ 157.137701] drm_atomic_helper_commit+0x13d/0x2e0
[ 157.142671] ? drm_atomic_nonblocking_commit+0xa0/0x180
[ 157.147988] drm_mode_atomic_ioctl+0x766/0xe40
[...]
[ 157.346424] ---[ end trace 0000000000000000 ]---
Acquiring GEM handles for the framebuffer's GEM buffer objects prevents
this from happening. The framebuffer's cleanup later puts the handle
references.
Commit 1a148af06000 ("drm/gem-shmem: Use dma_buf from GEM object
instance") triggers the segmentation fault easily by using the dma-buf
field more widely. The underlying issue with reference counting has
been present before.
v2:
- acquire the handle instead of the BO (Christian)
- fix comment style (Christian)
- drop the Fixes tag (Christian)
- rename err_ gotos
- add missing Link tag
CVSS Score
5.5
EPSS Score
0.0
Published
2025-07-25