Linux: >> Linux Kernel >> 4.4.155 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
ring-buffer: Fix deadloop issue on reading trace_pipe
Soft lockup occurs when reading file 'trace_pipe':
watchdog: BUG: soft lockup - CPU#6 stuck for 22s! [cat:4488]
[...]
RIP: 0010:ring_buffer_empty_cpu+0xed/0x170
RSP: 0018:ffff88810dd6fc48 EFLAGS: 00000246
RAX: 0000000000000000 RBX: 0000000000000246 RCX: ffffffff93d1aaeb
RDX: ffff88810a280040 RSI: 0000000000000008 RDI: ffff88811164b218
RBP: ffff88811164b218 R08: 0000000000000000 R09: ffff88815156600f
R10: ffffed102a2acc01 R11: 0000000000000001 R12: 0000000051651901
R13: 0000000000000000 R14: ffff888115e49500 R15: 0000000000000000
[...]
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f8d853c2000 CR3: 000000010dcd8000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
__find_next_entry+0x1a8/0x4b0
? peek_next_entry+0x250/0x250
? down_write+0xa5/0x120
? down_write_killable+0x130/0x130
trace_find_next_entry_inc+0x3b/0x1d0
tracing_read_pipe+0x423/0xae0
? tracing_splice_read_pipe+0xcb0/0xcb0
vfs_read+0x16b/0x490
ksys_read+0x105/0x210
? __ia32_sys_pwrite64+0x200/0x200
? switch_fpu_return+0x108/0x220
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x61/0xc6
Through the vmcore, I found it's because in tracing_read_pipe(),
ring_buffer_empty_cpu() found some buffer is not empty but then it
cannot read anything due to "rb_num_of_entries() == 0" always true,
Then it infinitely loop the procedure due to user buffer not been
filled, see following code path:
tracing_read_pipe() {
... ...
waitagain:
tracing_wait_pipe() // 1. find non-empty buffer here
trace_find_next_entry_inc() // 2. loop here try to find an entry
__find_next_entry()
ring_buffer_empty_cpu(); // 3. find non-empty buffer
peek_next_entry() // 4. but peek always return NULL
ring_buffer_peek()
rb_buffer_peek()
rb_get_reader_page()
// 5. because rb_num_of_entries() == 0 always true here
// then return NULL
// 6. user buffer not been filled so goto 'waitgain'
// and eventually leads to an deadloop in kernel!!!
}
By some analyzing, I found that when resetting ringbuffer, the 'entries'
of its pages are not all cleared (see rb_reset_cpu()). Then when reducing
the ringbuffer, and if some reduced pages exist dirty 'entries' data, they
will be added into 'cpu_buffer->overrun' (see rb_remove_pages()), which
cause wrong 'overrun' count and eventually cause the deadloop issue.
To fix it, we need to clear every pages in rb_reset_cpu().
CVSS Score
7.1
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
bnxt: avoid overflow in bnxt_get_nvram_directory()
The value of an arithmetic expression is subject
of possible overflow due to a failure to cast operands to a larger data
type before performing arithmetic. Used macro for multiplication instead
operator for avoiding overflow.
Found by Security Code and Linux Verification
Center (linuxtesting.org) with SVACE.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
Drivers: hv: vmbus: Don't dereference ACPI root object handle
Since the commit referenced in the Fixes: tag below the VMBus client driver
is walking the ACPI namespace up from the VMBus ACPI device to the ACPI
namespace root object trying to find Hyper-V MMIO ranges.
However, if it is not able to find them it ends trying to walk resources of
the ACPI namespace root object itself.
This object has all-ones handle, which causes a NULL pointer dereference
in the ACPI code (from dereferencing this pointer with an offset).
This in turn causes an oops on boot with VMBus host implementations that do
not provide Hyper-V MMIO ranges in their VMBus ACPI device or its
ancestors.
The QEMU VMBus implementation is an example of such implementation.
I guess providing these ranges is optional, since all tested Windows
versions seem to be able to use VMBus devices without them.
Fix this by explicitly terminating the lookup at the ACPI namespace root
object.
Note that Linux guests under KVM/QEMU do not use the Hyper-V PV interface
by default - they only do so if the KVM PV interface is missing or
disabled.
Example stack trace of such oops:
[ 3.710827] ? __die+0x1f/0x60
[ 3.715030] ? page_fault_oops+0x159/0x460
[ 3.716008] ? exc_page_fault+0x73/0x170
[ 3.716959] ? asm_exc_page_fault+0x22/0x30
[ 3.717957] ? acpi_ns_lookup+0x7a/0x4b0
[ 3.718898] ? acpi_ns_internalize_name+0x79/0xc0
[ 3.720018] acpi_ns_get_node_unlocked+0xb5/0xe0
[ 3.721120] ? acpi_ns_check_object_type+0xfe/0x200
[ 3.722285] ? acpi_rs_convert_aml_to_resource+0x37/0x6e0
[ 3.723559] ? down_timeout+0x3a/0x60
[ 3.724455] ? acpi_ns_get_node+0x3a/0x60
[ 3.725412] acpi_ns_get_node+0x3a/0x60
[ 3.726335] acpi_ns_evaluate+0x1c3/0x2c0
[ 3.727295] acpi_ut_evaluate_object+0x64/0x1b0
[ 3.728400] acpi_rs_get_method_data+0x2b/0x70
[ 3.729476] ? vmbus_platform_driver_probe+0x1d0/0x1d0 [hv_vmbus]
[ 3.730940] ? vmbus_platform_driver_probe+0x1d0/0x1d0 [hv_vmbus]
[ 3.732411] acpi_walk_resources+0x78/0xd0
[ 3.733398] vmbus_platform_driver_probe+0x9f/0x1d0 [hv_vmbus]
[ 3.734802] platform_probe+0x3d/0x90
[ 3.735684] really_probe+0x19b/0x400
[ 3.736570] ? __device_attach_driver+0x100/0x100
[ 3.737697] __driver_probe_device+0x78/0x160
[ 3.738746] driver_probe_device+0x1f/0x90
[ 3.739743] __driver_attach+0xc2/0x1b0
[ 3.740671] bus_for_each_dev+0x70/0xc0
[ 3.741601] bus_add_driver+0x10e/0x210
[ 3.742527] driver_register+0x55/0xf0
[ 3.744412] ? 0xffffffffc039a000
[ 3.745207] hv_acpi_init+0x3c/0x1000 [hv_vmbus]
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
ALSA: ac97: Fix possible NULL dereference in snd_ac97_mixer
smatch error:
sound/pci/ac97/ac97_codec.c:2354 snd_ac97_mixer() error:
we previously assumed 'rac97' could be null (see line 2072)
remove redundant assignment, return error if rac97 is NULL.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
fbdev: omapfb: lcd_mipid: Fix an error handling path in mipid_spi_probe()
If 'mipid_detect()' fails, we must free 'md' to avoid a memory leak.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath6kl: reduce WARN to dev_dbg() in callback
The warn is triggered on a known race condition, documented in the code above
the test, that is correctly handled. Using WARN() hinders automated testing.
Reducing severity.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
wifi: ath9k: hif_usb: fix memory leak of remain_skbs
hif_dev->remain_skb is allocated and used exclusively in
ath9k_hif_usb_rx_stream(). It is implied that an allocated remain_skb is
processed and subsequently freed (in error paths) only during the next
call of ath9k_hif_usb_rx_stream().
So, if the urbs are deallocated between those two calls due to the device
deinitialization or suspend, it is possible that ath9k_hif_usb_rx_stream()
is not called next time and the allocated remain_skb is leaked. Our local
Syzkaller instance was able to trigger that.
remain_skb makes sense when receiving two consecutive urbs which are
logically linked together, i.e. a specific data field from the first skb
indicates a cached skb to be allocated, memcpy'd with some data and
subsequently processed in the next call to ath9k_hif_usb_rx_stream(). Urbs
deallocation supposedly makes that link irrelevant so we need to free the
cached skb in those cases.
Fix the leak by introducing a function to explicitly free remain_skb (if
it is not NULL) when the rx urbs have been deallocated. remain_skb is NULL
when it has not been allocated at all (hif_dev struct is kzalloced) or
when it has been processed in next call to ath9k_hif_usb_rx_stream().
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
media: radio-shark: Add endpoint checks
The syzbot fuzzer was able to provoke a WARNING from the radio-shark2
driver:
------------[ cut here ]------------
usb 1-1: BOGUS urb xfer, pipe 1 != type 3
WARNING: CPU: 0 PID: 3271 at drivers/usb/core/urb.c:504 usb_submit_urb+0xed2/0x1880 drivers/usb/core/urb.c:504
Modules linked in:
CPU: 0 PID: 3271 Comm: kworker/0:3 Not tainted 6.1.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Workqueue: usb_hub_wq hub_event
RIP: 0010:usb_submit_urb+0xed2/0x1880 drivers/usb/core/urb.c:504
Code: 7c 24 18 e8 00 36 ea fb 48 8b 7c 24 18 e8 36 1c 02 ff 41 89 d8 44 89 e1 4c 89 ea 48 89 c6 48 c7 c7 a0 b6 90 8a e8 9a 29 b8 03 <0f> 0b e9 58 f8 ff ff e8 d2 35 ea fb 48 81 c5 c0 05 00 00 e9 84 f7
RSP: 0018:ffffc90003876dd0 EFLAGS: 00010282
RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000
RDX: ffff8880750b0040 RSI: ffffffff816152b8 RDI: fffff5200070edac
RBP: ffff8880172d81e0 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000080000000 R11: 0000000000000000 R12: 0000000000000001
R13: ffff8880285c5040 R14: 0000000000000002 R15: ffff888017158200
FS: 0000000000000000(0000) GS:ffff8880b9a00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe03235b90 CR3: 000000000bc8e000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
usb_start_wait_urb+0x101/0x4b0 drivers/usb/core/message.c:58
usb_bulk_msg+0x226/0x550 drivers/usb/core/message.c:387
shark_write_reg+0x1ff/0x2e0 drivers/media/radio/radio-shark2.c:88
...
The problem was caused by the fact that the driver does not check
whether the endpoints it uses are actually present and have the
appropriate types. This can be fixed by adding a simple check of
these endpoints (and similarly for the radio-shark driver).
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
netfilter: conntrack: fix wrong ct->timeout value
(struct nf_conn)->timeout is an interval before the conntrack
confirmed. After confirmed, it becomes a timestamp.
It is observed that timeout of an unconfirmed conntrack:
- Set by calling ctnetlink_change_timeout(). As a result,
`nfct_time_stamp` was wrongly added to `ct->timeout` twice.
- Get by calling ctnetlink_dump_timeout(). As a result,
`nfct_time_stamp` was wrongly subtracted.
Call Trace:
<TASK>
dump_stack_lvl
ctnetlink_dump_timeout
__ctnetlink_glue_build
ctnetlink_glue_build
__nfqnl_enqueue_packet
nf_queue
nf_hook_slow
ip_mc_output
? __pfx_ip_finish_output
ip_send_skb
? __pfx_dst_output
udp_send_skb
udp_sendmsg
? __pfx_ip_generic_getfrag
sock_sendmsg
Separate the 2 cases in:
- Setting `ct->timeout` in __nf_ct_set_timeout().
- Getting `ct->timeout` in ctnetlink_dump_timeout().
Pablo appends:
Update ctnetlink to set up the timeout _after_ the IPS_CONFIRMED flag is
set on, otherwise conntrack creation via ctnetlink breaks.
Note that the problem described in this patch occurs since the
introduction of the nfnetlink_queue conntrack support, select a
sufficiently old Fixes: tag for -stable kernel to pick up this fix.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07
In the Linux kernel, the following vulnerability has been resolved:
net/sched: sch_fq: fix integer overflow of "credit"
if sch_fq is configured with "initial quantum" having values greater than
INT_MAX, the first assignment of "credit" does signed integer overflow to
a very negative value.
In this situation, the syzkaller script provided by Cristoph triggers the
CPU soft-lockup warning even with few sockets. It's not an infinite loop,
but "credit" wasn't probably meant to be minus 2Gb for each new flow.
Capping "initial quantum" to INT_MAX proved to fix the issue.
v2: validation of "initial quantum" is done in fq_policy, instead of open
coding in fq_change() _ suggested by Jakub Kicinski
CVSS Score
5.5
EPSS Score
0.0
Published
2025-10-07