In the Linux kernel, the following vulnerability has been resolved:
af_unix: Don't leave consecutive consumed OOB skbs.
Jann Horn reported a use-after-free in unix_stream_read_generic().
The following sequences reproduce the issue:
$ python3
from socket import *
s1, s2 = socketpair(AF_UNIX, SOCK_STREAM)
s1.send(b'x', MSG_OOB)
s2.recv(1, MSG_OOB) # leave a consumed OOB skb
s1.send(b'y', MSG_OOB)
s2.recv(1, MSG_OOB) # leave a consumed OOB skb
s1.send(b'z', MSG_OOB)
s2.recv(1) # recv 'z' illegally
s2.recv(1, MSG_OOB) # access 'z' skb (use-after-free)
Even though a user reads OOB data, the skb holding the data stays on
the recv queue to mark the OOB boundary and break the next recv().
After the last send() in the scenario above, the sk2's recv queue has
2 leading consumed OOB skbs and 1 real OOB skb.
Then, the following happens during the next recv() without MSG_OOB
1. unix_stream_read_generic() peeks the first consumed OOB skb
2. manage_oob() returns the next consumed OOB skb
3. unix_stream_read_generic() fetches the next not-yet-consumed OOB skb
4. unix_stream_read_generic() reads and frees the OOB skb
, and the last recv(MSG_OOB) triggers KASAN splat.
The 3. above occurs because of the SO_PEEK_OFF code, which does not
expect unix_skb_len(skb) to be 0, but this is true for such consumed
OOB skbs.
while (skip >= unix_skb_len(skb)) {
skip -= unix_skb_len(skb);
skb = skb_peek_next(skb, &sk->sk_receive_queue);
...
}
In addition to this use-after-free, there is another issue that
ioctl(SIOCATMARK) does not function properly with consecutive consumed
OOB skbs.
So, nothing good comes out of such a situation.
Instead of complicating manage_oob(), ioctl() handling, and the next
ECONNRESET fix by introducing a loop for consecutive consumed OOB skbs,
let's not leave such consecutive OOB unnecessarily.
Now, while receiving an OOB skb in unix_stream_recv_urg(), if its
previous skb is a consumed OOB skb, it is freed.
[0]:
BUG: KASAN: slab-use-after-free in unix_stream_read_actor (net/unix/af_unix.c:3027)
Read of size 4 at addr ffff888106ef2904 by task python3/315
CPU: 2 UID: 0 PID: 315 Comm: python3 Not tainted 6.16.0-rc1-00407-gec315832f6f9 #8 PREEMPT(voluntary)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-4.fc42 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl (lib/dump_stack.c:122)
print_report (mm/kasan/report.c:409 mm/kasan/report.c:521)
kasan_report (mm/kasan/report.c:636)
unix_stream_read_actor (net/unix/af_unix.c:3027)
unix_stream_read_generic (net/unix/af_unix.c:2708 net/unix/af_unix.c:2847)
unix_stream_recvmsg (net/unix/af_unix.c:3048)
sock_recvmsg (net/socket.c:1063 (discriminator 20) net/socket.c:1085 (discriminator 20))
__sys_recvfrom (net/socket.c:2278)
__x64_sys_recvfrom (net/socket.c:2291 (discriminator 1) net/socket.c:2287 (discriminator 1) net/socket.c:2287 (discriminator 1))
do_syscall_64 (arch/x86/entry/syscall_64.c:63 (discriminator 1) arch/x86/entry/syscall_64.c:94 (discriminator 1))
entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:130)
RIP: 0033:0x7f8911fcea06
Code: 5d e8 41 8b 93 08 03 00 00 59 5e 48 83 f8 fc 75 19 83 e2 39 83 fa 08 75 11 e8 26 ff ff ff 66 0f 1f 44 00 00 48 8b 45 10 0f 05 <48> 8b 5d f8 c9 c3 0f 1f 40 00 f3 0f 1e fa 55 48 89 e5 48 83 ec 08
RSP: 002b:00007fffdb0dccb0 EFLAGS: 00000202 ORIG_RAX: 000000000000002d
RAX: ffffffffffffffda RBX: 00007fffdb0dcdc8 RCX: 00007f8911fcea06
RDX: 0000000000000001 RSI: 00007f8911a5e060 RDI: 0000000000000006
RBP: 00007fffdb0dccd0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000202 R12: 00007f89119a7d20
R13: ffffffffc4653600 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Allocated by task 315:
kasan_save_stack (mm/kasan/common.c:48)
kasan_save_track (mm/kasan/common.c:60 (discriminator 1) mm/kasan/common.c:69 (discriminator 1))
__kasan_slab_alloc (mm/kasan/common.c:348)
kmem_cache_alloc_
---truncated---
In the Linux kernel, the following vulnerability has been resolved:
sched/rt: Fix race in push_rt_task
Overview
========
When a CPU chooses to call push_rt_task and picks a task to push to
another CPU's runqueue then it will call find_lock_lowest_rq method
which would take a double lock on both CPUs' runqueues. If one of the
locks aren't readily available, it may lead to dropping the current
runqueue lock and reacquiring both the locks at once. During this window
it is possible that the task is already migrated and is running on some
other CPU. These cases are already handled. However, if the task is
migrated and has already been executed and another CPU is now trying to
wake it up (ttwu) such that it is queued again on the runqeue
(on_rq is 1) and also if the task was run by the same CPU, then the
current checks will pass even though the task was migrated out and is no
longer in the pushable tasks list.
Crashes
=======
This bug resulted in quite a few flavors of crashes triggering kernel
panics with various crash signatures such as assert failures, page
faults, null pointer dereferences, and queue corruption errors all
coming from scheduler itself.
Some of the crashes:
-> kernel BUG at kernel/sched/rt.c:1616! BUG_ON(idx >= MAX_RT_PRIO)
Call Trace:
? __die_body+0x1a/0x60
? die+0x2a/0x50
? do_trap+0x85/0x100
? pick_next_task_rt+0x6e/0x1d0
? do_error_trap+0x64/0xa0
? pick_next_task_rt+0x6e/0x1d0
? exc_invalid_op+0x4c/0x60
? pick_next_task_rt+0x6e/0x1d0
? asm_exc_invalid_op+0x12/0x20
? pick_next_task_rt+0x6e/0x1d0
__schedule+0x5cb/0x790
? update_ts_time_stats+0x55/0x70
schedule_idle+0x1e/0x40
do_idle+0x15e/0x200
cpu_startup_entry+0x19/0x20
start_secondary+0x117/0x160
secondary_startup_64_no_verify+0xb0/0xbb
-> BUG: kernel NULL pointer dereference, address: 00000000000000c0
Call Trace:
? __die_body+0x1a/0x60
? no_context+0x183/0x350
? __warn+0x8a/0xe0
? exc_page_fault+0x3d6/0x520
? asm_exc_page_fault+0x1e/0x30
? pick_next_task_rt+0xb5/0x1d0
? pick_next_task_rt+0x8c/0x1d0
__schedule+0x583/0x7e0
? update_ts_time_stats+0x55/0x70
schedule_idle+0x1e/0x40
do_idle+0x15e/0x200
cpu_startup_entry+0x19/0x20
start_secondary+0x117/0x160
secondary_startup_64_no_verify+0xb0/0xbb
-> BUG: unable to handle page fault for address: ffff9464daea5900
kernel BUG at kernel/sched/rt.c:1861! BUG_ON(rq->cpu != task_cpu(p))
-> kernel BUG at kernel/sched/rt.c:1055! BUG_ON(!rq->nr_running)
Call Trace:
? __die_body+0x1a/0x60
? die+0x2a/0x50
? do_trap+0x85/0x100
? dequeue_top_rt_rq+0xa2/0xb0
? do_error_trap+0x64/0xa0
? dequeue_top_rt_rq+0xa2/0xb0
? exc_invalid_op+0x4c/0x60
? dequeue_top_rt_rq+0xa2/0xb0
? asm_exc_invalid_op+0x12/0x20
? dequeue_top_rt_rq+0xa2/0xb0
dequeue_rt_entity+0x1f/0x70
dequeue_task_rt+0x2d/0x70
__schedule+0x1a8/0x7e0
? blk_finish_plug+0x25/0x40
schedule+0x3c/0xb0
futex_wait_queue_me+0xb6/0x120
futex_wait+0xd9/0x240
do_futex+0x344/0xa90
? get_mm_exe_file+0x30/0x60
? audit_exe_compare+0x58/0x70
? audit_filter_rules.constprop.26+0x65e/0x1220
__x64_sys_futex+0x148/0x1f0
do_syscall_64+0x30/0x80
entry_SYSCALL_64_after_hwframe+0x62/0xc7
-> BUG: unable to handle page fault for address: ffff8cf3608bc2c0
Call Trace:
? __die_body+0x1a/0x60
? no_context+0x183/0x350
? spurious_kernel_fault+0x171/0x1c0
? exc_page_fault+0x3b6/0x520
? plist_check_list+0x15/0x40
? plist_check_list+0x2e/0x40
? asm_exc_page_fault+0x1e/0x30
? _cond_resched+0x15/0x30
? futex_wait_queue_me+0xc8/0x120
? futex_wait+0xd9/0x240
? try_to_wake_up+0x1b8/0x490
? futex_wake+0x78/0x160
? do_futex+0xcd/0xa90
? plist_check_list+0x15/0x40
? plist_check_list+0x2e/0x40
? plist_del+0x6a/0xd0
? plist_check_list+0x15/0x40
? plist_check_list+0x2e/0x40
? dequeue_pushable_task+0x20/0x70
? __schedule+0x382/0x7e0
? asm_sysvec_reschedule_i
---truncated---
In the Linux kernel, the following vulnerability has been resolved:
media: cxusb: no longer judge rbuf when the write fails
syzbot reported a uninit-value in cxusb_i2c_xfer. [1]
Only when the write operation of usb_bulk_msg() in dvb_usb_generic_rw()
succeeds and rlen is greater than 0, the read operation of usb_bulk_msg()
will be executed to read rlen bytes of data from the dvb device into the
rbuf.
In this case, although rlen is 1, the write operation failed which resulted
in the dvb read operation not being executed, and ultimately variable i was
not initialized.
[1]
BUG: KMSAN: uninit-value in cxusb_gpio_tuner drivers/media/usb/dvb-usb/cxusb.c:124 [inline]
BUG: KMSAN: uninit-value in cxusb_i2c_xfer+0x153a/0x1a60 drivers/media/usb/dvb-usb/cxusb.c:196
cxusb_gpio_tuner drivers/media/usb/dvb-usb/cxusb.c:124 [inline]
cxusb_i2c_xfer+0x153a/0x1a60 drivers/media/usb/dvb-usb/cxusb.c:196
__i2c_transfer+0xe25/0x3150 drivers/i2c/i2c-core-base.c:-1
i2c_transfer+0x317/0x4a0 drivers/i2c/i2c-core-base.c:2315
i2c_transfer_buffer_flags+0x125/0x1e0 drivers/i2c/i2c-core-base.c:2343
i2c_master_send include/linux/i2c.h:109 [inline]
i2cdev_write+0x210/0x280 drivers/i2c/i2c-dev.c:183
do_loop_readv_writev fs/read_write.c:848 [inline]
vfs_writev+0x963/0x14e0 fs/read_write.c:1057
do_writev+0x247/0x5c0 fs/read_write.c:1101
__do_sys_writev fs/read_write.c:1169 [inline]
__se_sys_writev fs/read_write.c:1166 [inline]
__x64_sys_writev+0x98/0xe0 fs/read_write.c:1166
x64_sys_call+0x2229/0x3c80 arch/x86/include/generated/asm/syscalls_64.h:21
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x1e0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
In the Linux kernel, the following vulnerability has been resolved:
nfsd: Initialize ssc before laundromat_work to prevent NULL dereference
In nfs4_state_start_net(), laundromat_work may access nfsd_ssc through
nfs4_laundromat -> nfsd4_ssc_expire_umount. If nfsd_ssc isn't initialized,
this can cause NULL pointer dereference.
Normally the delayed start of laundromat_work allows sufficient time for
nfsd_ssc initialization to complete. However, when the kernel waits too
long for userspace responses (e.g. in nfs4_state_start_net ->
nfsd4_end_grace -> nfsd4_record_grace_done -> nfsd4_cld_grace_done ->
cld_pipe_upcall -> __cld_pipe_upcall -> wait_for_completion path), the
delayed work may start before nfsd_ssc initialization finishes.
Fix this by moving nfsd_ssc initialization before starting laundromat_work.
In the Linux kernel, the following vulnerability has been resolved:
NFSD: fix race between nfsd registration and exports_proc
As of now nfsd calls create_proc_exports_entry() at start of init_nfsd
and cleanup by remove_proc_entry() at last of exit_nfsd.
Which causes kernel OOPs if there is race between below 2 operations:
(i) exportfs -r
(ii) mount -t nfsd none /proc/fs/nfsd
for 5.4 kernel ARM64:
CPU 1:
el1_irq+0xbc/0x180
arch_counter_get_cntvct+0x14/0x18
running_clock+0xc/0x18
preempt_count_add+0x88/0x110
prep_new_page+0xb0/0x220
get_page_from_freelist+0x2d8/0x1778
__alloc_pages_nodemask+0x15c/0xef0
__vmalloc_node_range+0x28c/0x478
__vmalloc_node_flags_caller+0x8c/0xb0
kvmalloc_node+0x88/0xe0
nfsd_init_net+0x6c/0x108 [nfsd]
ops_init+0x44/0x170
register_pernet_operations+0x114/0x270
register_pernet_subsys+0x34/0x50
init_nfsd+0xa8/0x718 [nfsd]
do_one_initcall+0x54/0x2e0
CPU 2 :
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010
PC is at : exports_net_open+0x50/0x68 [nfsd]
Call trace:
exports_net_open+0x50/0x68 [nfsd]
exports_proc_open+0x2c/0x38 [nfsd]
proc_reg_open+0xb8/0x198
do_dentry_open+0x1c4/0x418
vfs_open+0x38/0x48
path_openat+0x28c/0xf18
do_filp_open+0x70/0xe8
do_sys_open+0x154/0x248
Sometimes it crashes at exports_net_open() and sometimes cache_seq_next_rcu().
and same is happening on latest 6.14 kernel as well:
[ 0.000000] Linux version 6.14.0-rc5-next-20250304-dirty
...
[ 285.455918] Unable to handle kernel paging request at virtual address 00001f4800001f48
...
[ 285.464902] pc : cache_seq_next_rcu+0x78/0xa4
...
[ 285.469695] Call trace:
[ 285.470083] cache_seq_next_rcu+0x78/0xa4 (P)
[ 285.470488] seq_read+0xe0/0x11c
[ 285.470675] proc_reg_read+0x9c/0xf0
[ 285.470874] vfs_read+0xc4/0x2fc
[ 285.471057] ksys_read+0x6c/0xf4
[ 285.471231] __arm64_sys_read+0x1c/0x28
[ 285.471428] invoke_syscall+0x44/0x100
[ 285.471633] el0_svc_common.constprop.0+0x40/0xe0
[ 285.471870] do_el0_svc_compat+0x1c/0x34
[ 285.472073] el0_svc_compat+0x2c/0x80
[ 285.472265] el0t_32_sync_handler+0x90/0x140
[ 285.472473] el0t_32_sync+0x19c/0x1a0
[ 285.472887] Code: f9400885 93407c23 937d7c27 11000421 (f86378a3)
[ 285.473422] ---[ end trace 0000000000000000 ]---
It reproduced simply with below script:
while [ 1 ]
do
/exportfs -r
done &
while [ 1 ]
do
insmod /nfsd.ko
mount -t nfsd none /proc/fs/nfsd
umount /proc/fs/nfsd
rmmod nfsd
done &
So exporting interfaces to user space shall be done at last and
cleanup at first place.
With change there is no Kernel OOPs.
In the Linux kernel, the following vulnerability has been resolved:
media: imx-jpeg: Cleanup after an allocation error
When allocation failures are not cleaned up by the driver, further
allocation errors will be false-positives, which will cause buffers to
remain uninitialized and cause NULL pointer dereferences.
Ensure proper cleanup of failed allocations to prevent these issues.
In the Linux kernel, the following vulnerability has been resolved:
media: vivid: Change the siize of the composing
syzkaller found a bug:
BUG: KASAN: vmalloc-out-of-bounds in tpg_fill_plane_pattern drivers/media/common/v4l2-tpg/v4l2-tpg-core.c:2608 [inline]
BUG: KASAN: vmalloc-out-of-bounds in tpg_fill_plane_buffer+0x1a9c/0x5af0 drivers/media/common/v4l2-tpg/v4l2-tpg-core.c:2705
Write of size 1440 at addr ffffc9000d0ffda0 by task vivid-000-vid-c/5304
CPU: 0 UID: 0 PID: 5304 Comm: vivid-000-vid-c Not tainted 6.14.0-rc2-syzkaller-00039-g09fbf3d50205 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
print_address_description mm/kasan/report.c:378 [inline]
print_report+0x169/0x550 mm/kasan/report.c:489
kasan_report+0x143/0x180 mm/kasan/report.c:602
kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
__asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
tpg_fill_plane_pattern drivers/media/common/v4l2-tpg/v4l2-tpg-core.c:2608 [inline]
tpg_fill_plane_buffer+0x1a9c/0x5af0 drivers/media/common/v4l2-tpg/v4l2-tpg-core.c:2705
vivid_fillbuff drivers/media/test-drivers/vivid/vivid-kthread-cap.c:470 [inline]
vivid_thread_vid_cap_tick+0xf8e/0x60d0 drivers/media/test-drivers/vivid/vivid-kthread-cap.c:629
vivid_thread_vid_cap+0x8aa/0xf30 drivers/media/test-drivers/vivid/vivid-kthread-cap.c:767
kthread+0x7a9/0x920 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
The composition size cannot be larger than the size of fmt_cap_rect.
So execute v4l2_rect_map_inside() even if has_compose_cap == 0.
In the Linux kernel, the following vulnerability has been resolved:
hwmon: (ftsteutates) Fix TOCTOU race in fts_read()
In the fts_read() function, when handling hwmon_pwm_auto_channels_temp,
the code accesses the shared variable data->fan_source[channel] twice
without holding any locks. It is first checked against
FTS_FAN_SOURCE_INVALID, and if the check passes, it is read again
when used as an argument to the BIT() macro.
This creates a Time-of-Check to Time-of-Use (TOCTOU) race condition.
Another thread executing fts_update_device() can modify the value of
data->fan_source[channel] between the check and its use. If the value
is changed to FTS_FAN_SOURCE_INVALID (0xff) during this window, the
BIT() macro will be called with a large shift value (BIT(255)).
A bit shift by a value greater than or equal to the type width is
undefined behavior and can lead to a crash or incorrect values being
returned to userspace.
Fix this by reading data->fan_source[channel] into a local variable
once, eliminating the race condition. Additionally, add a bounds check
to ensure the value is less than BITS_PER_LONG before passing it to
the BIT() macro, making the code more robust against undefined behavior.
This possible bug was found by an experimental static analysis tool
developed by our team.