Linux: >> Linux Kernel >> 4.19.298 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
x86/vmscape: Add conditional IBPB mitigation
VMSCAPE is a vulnerability that exploits insufficient branch predictor
isolation between a guest and a userspace hypervisor (like QEMU). Existing
mitigations already protect kernel/KVM from a malicious guest. Userspace
can additionally be protected by flushing the branch predictors after a
VMexit.
Since it is the userspace that consumes the poisoned branch predictors,
conditionally issue an IBPB after a VMexit and before returning to
userspace. Workloads that frequently switch between hypervisor and
userspace will incur the most overhead from the new IBPB.
This new IBPB is not integrated with the existing IBPB sites. For
instance, a task can use the existing speculation control prctl() to
get an IBPB at context switch time. With this implementation, the
IBPB is doubled up: one at context switch and another before running
userspace.
The intent is to integrate and optimize these cases post-embargo.
[ dhansen: elaborate on suboptimal IBPB solution ]
CVSS Score
5.5
EPSS Score
0.0
Published
2025-09-11
In the Linux kernel, the following vulnerability has been resolved:
parisc: Drop WARN_ON_ONCE() from flush_cache_vmap
I have observed warning to occassionally trigger.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-09-11
In the Linux kernel, the following vulnerability has been resolved:
jbd2: prevent softlockup in jbd2_log_do_checkpoint()
Both jbd2_log_do_checkpoint() and jbd2_journal_shrink_checkpoint_list()
periodically release j_list_lock after processing a batch of buffers to
avoid long hold times on the j_list_lock. However, since both functions
contend for j_list_lock, the combined time spent waiting and processing
can be significant.
jbd2_journal_shrink_checkpoint_list() explicitly calls cond_resched() when
need_resched() is true to avoid softlockups during prolonged operations.
But jbd2_log_do_checkpoint() only exits its loop when need_resched() is
true, relying on potentially sleeping functions like __flush_batch() or
wait_on_buffer() to trigger rescheduling. If those functions do not sleep,
the kernel may hit a softlockup.
watchdog: BUG: soft lockup - CPU#3 stuck for 156s! [kworker/u129:2:373]
CPU: 3 PID: 373 Comm: kworker/u129:2 Kdump: loaded Not tainted 6.6.0+ #10
Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.27 06/13/2017
Workqueue: writeback wb_workfn (flush-7:2)
pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : native_queued_spin_lock_slowpath+0x358/0x418
lr : jbd2_log_do_checkpoint+0x31c/0x438 [jbd2]
Call trace:
native_queued_spin_lock_slowpath+0x358/0x418
jbd2_log_do_checkpoint+0x31c/0x438 [jbd2]
__jbd2_log_wait_for_space+0xfc/0x2f8 [jbd2]
add_transaction_credits+0x3bc/0x418 [jbd2]
start_this_handle+0xf8/0x560 [jbd2]
jbd2__journal_start+0x118/0x228 [jbd2]
__ext4_journal_start_sb+0x110/0x188 [ext4]
ext4_do_writepages+0x3dc/0x740 [ext4]
ext4_writepages+0xa4/0x190 [ext4]
do_writepages+0x94/0x228
__writeback_single_inode+0x48/0x318
writeback_sb_inodes+0x204/0x590
__writeback_inodes_wb+0x54/0xf8
wb_writeback+0x2cc/0x3d8
wb_do_writeback+0x2e0/0x2f8
wb_workfn+0x80/0x2a8
process_one_work+0x178/0x3e8
worker_thread+0x234/0x3b8
kthread+0xf0/0x108
ret_from_fork+0x10/0x20
So explicitly call cond_resched() in jbd2_log_do_checkpoint() to avoid
softlockup.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-09-11
In the Linux kernel, the following vulnerability has been resolved:
PCI: endpoint: Fix configfs group list head handling
Doing a list_del() on the epf_group field of struct pci_epf_driver in
pci_epf_remove_cfs() is not correct as this field is a list head, not
a list entry. This list_del() call triggers a KASAN warning when an
endpoint function driver which has a configfs attribute group is torn
down:
==================================================================
BUG: KASAN: slab-use-after-free in pci_epf_remove_cfs+0x17c/0x198
Write of size 8 at addr ffff00010f4a0d80 by task rmmod/319
CPU: 3 UID: 0 PID: 319 Comm: rmmod Not tainted 6.16.0-rc2 #1 NONE
Hardware name: Radxa ROCK 5B (DT)
Call trace:
show_stack+0x2c/0x84 (C)
dump_stack_lvl+0x70/0x98
print_report+0x17c/0x538
kasan_report+0xb8/0x190
__asan_report_store8_noabort+0x20/0x2c
pci_epf_remove_cfs+0x17c/0x198
pci_epf_unregister_driver+0x18/0x30
nvmet_pci_epf_cleanup_module+0x24/0x30 [nvmet_pci_epf]
__arm64_sys_delete_module+0x264/0x424
invoke_syscall+0x70/0x260
el0_svc_common.constprop.0+0xac/0x230
do_el0_svc+0x40/0x58
el0_svc+0x48/0xdc
el0t_64_sync_handler+0x10c/0x138
el0t_64_sync+0x198/0x19c
...
Remove this incorrect list_del() call from pci_epf_remove_cfs().
CVSS Score
7.8
EPSS Score
0.0
Published
2025-09-11
In the Linux kernel, the following vulnerability has been resolved:
soc: qcom: mdt_loader: Ensure we don't read past the ELF header
When the MDT loader is used in remoteproc, the ELF header is sanitized
beforehand, but that's not necessary the case for other clients.
Validate the size of the firmware buffer to ensure that we don't read
past the end as we iterate over the header. e_phentsize and e_shentsize
are validated as well, to ensure that the assumptions about step size in
the traversal are valid.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-09-11
In the Linux kernel, the following vulnerability has been resolved:
net: bridge: fix soft lockup in br_multicast_query_expired()
When set multicast_query_interval to a large value, the local variable
'time' in br_multicast_send_query() may overflow. If the time is smaller
than jiffies, the timer will expire immediately, and then call mod_timer()
again, which creates a loop and may trigger the following soft lockup
issue.
watchdog: BUG: soft lockup - CPU#1 stuck for 221s! [rb_consumer:66]
CPU: 1 UID: 0 PID: 66 Comm: rb_consumer Not tainted 6.16.0+ #259 PREEMPT(none)
Call Trace:
<IRQ>
__netdev_alloc_skb+0x2e/0x3a0
br_ip6_multicast_alloc_query+0x212/0x1b70
__br_multicast_send_query+0x376/0xac0
br_multicast_send_query+0x299/0x510
br_multicast_query_expired.constprop.0+0x16d/0x1b0
call_timer_fn+0x3b/0x2a0
__run_timers+0x619/0x950
run_timer_softirq+0x11c/0x220
handle_softirqs+0x18e/0x560
__irq_exit_rcu+0x158/0x1a0
sysvec_apic_timer_interrupt+0x76/0x90
</IRQ>
This issue can be reproduced with:
ip link add br0 type bridge
echo 1 > /sys/class/net/br0/bridge/multicast_querier
echo 0xffffffffffffffff >
/sys/class/net/br0/bridge/multicast_query_interval
ip link set dev br0 up
The multicast_startup_query_interval can also cause this issue. Similar to
the commit 99b40610956a ("net: bridge: mcast: add and enforce query
interval minimum"), add check for the query interval maximum to fix this
issue.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-09-11
In the Linux kernel, the following vulnerability has been resolved:
drm/hisilicon/hibmc: fix the hibmc loaded failed bug
When hibmc loaded failed, the driver use hibmc_unload to free the
resource, but the mutexes in mode.config are not init, which will
access an NULL pointer. Just change goto statement to return, because
hibnc_hw_init() doesn't need to free anything.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-09-11
In the Linux kernel, the following vulnerability has been resolved:
net/sched: Make cake_enqueue return NET_XMIT_CN when past buffer_limit
The following setup can trigger a WARNING in htb_activate due to
the condition: !cl->leaf.q->q.qlen
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 f: \
cake memlimit 1b
ping -I lo -f -c1 -s64 -W0.001 127.0.0.1
This is because the low memlimit leads to a low buffer_limit, which
causes packet dropping. However, cake_enqueue still returns
NET_XMIT_SUCCESS, causing htb_enqueue to call htb_activate with an
empty child qdisc. We should return NET_XMIT_CN when packets are
dropped from the same tin and flow.
I do not believe return value of NET_XMIT_CN is necessary for packet
drops in the case of ack filtering, as that is meant to optimize
performance, not to signal congestion.
CVSS Score
7.8
EPSS Score
0.0
Published
2025-09-11
In the Linux kernel, the following vulnerability has been resolved:
drm/amd/display: add null check
[WHY]
Prevents null pointer dereferences to enhance function robustness
[HOW]
Adds early null check and return false if invalid.
CVSS Score
5.5
EPSS Score
0.0
Published
2025-09-11
In the Linux kernel, the following vulnerability has been resolved:
ACPI: APEI: send SIGBUS to current task if synchronous memory error not recovered
If a synchronous error is detected as a result of user-space process
triggering a 2-bit uncorrected error, the CPU will take a synchronous
error exception such as Synchronous External Abort (SEA) on Arm64. The
kernel will queue a memory_failure() work which poisons the related
page, unmaps the page, and then sends a SIGBUS to the process, so that
a system wide panic can be avoided.
However, no memory_failure() work will be queued when abnormal
synchronous errors occur. These errors can include situations like
invalid PA, unexpected severity, no memory failure config support,
invalid GUID section, etc. In such a case, the user-space process will
trigger SEA again. This loop can potentially exceed the platform
firmware threshold or even trigger a kernel hard lockup, leading to a
system reboot.
Fix it by performing a force kill if no memory_failure() work is queued
for synchronous errors.
[ rjw: Changelog edits ]
CVSS Score
5.5
EPSS Score
0.0
Published
2025-09-11