Linux: >> Linux Kernel >> 6.1.109 Security Vulnerabilities
In the Linux kernel, the following vulnerability has been resolved:
NFSD: Prevent NULL dereference in nfsd4_process_cb_update()
@ses is initialized to NULL. If __nfsd4_find_backchannel() finds no
available backchannel session, setup_callback_client() will try to
dereference @ses and segfault.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-12-27
In the Linux kernel, the following vulnerability has been resolved:
f2fs: fix race in concurrent f2fs_stop_gc_thread
In my test case, concurrent calls to f2fs shutdown report the following
stack trace:
Oops: general protection fault, probably for non-canonical address 0xc6cfff63bb5513fc: 0000 [#1] PREEMPT SMP PTI
CPU: 0 UID: 0 PID: 678 Comm: f2fs_rep_shutdo Not tainted 6.12.0-rc5-next-20241029-g6fb2fa9805c5-dirty #85
Call Trace:
<TASK>
? show_regs+0x8b/0xa0
? __die_body+0x26/0xa0
? die_addr+0x54/0x90
? exc_general_protection+0x24b/0x5c0
? asm_exc_general_protection+0x26/0x30
? kthread_stop+0x46/0x390
f2fs_stop_gc_thread+0x6c/0x110
f2fs_do_shutdown+0x309/0x3a0
f2fs_ioc_shutdown+0x150/0x1c0
__f2fs_ioctl+0xffd/0x2ac0
f2fs_ioctl+0x76/0xe0
vfs_ioctl+0x23/0x60
__x64_sys_ioctl+0xce/0xf0
x64_sys_call+0x2b1b/0x4540
do_syscall_64+0xa7/0x240
entry_SYSCALL_64_after_hwframe+0x76/0x7e
The root cause is a race condition in f2fs_stop_gc_thread() called from
different f2fs shutdown paths:
[CPU0] [CPU1]
---------------------- -----------------------
f2fs_stop_gc_thread f2fs_stop_gc_thread
gc_th = sbi->gc_thread
gc_th = sbi->gc_thread
kfree(gc_th)
sbi->gc_thread = NULL
< gc_th != NULL >
kthread_stop(gc_th->f2fs_gc_task) //UAF
The commit c7f114d864ac ("f2fs: fix to avoid use-after-free in
f2fs_stop_gc_thread()") attempted to fix this issue by using a read
semaphore to prevent races between shutdown and remount threads, but
it fails to prevent all race conditions.
Fix it by converting to write lock of s_umount in f2fs_do_shutdown().
CVSS Score
7.8
EPSS Score
0.0
Published
2024-12-27
In the Linux kernel, the following vulnerability has been resolved:
virtiofs: use pages instead of pointer for kernel direct IO
When trying to insert a 10MB kernel module kept in a virtio-fs with cache
disabled, the following warning was reported:
------------[ cut here ]------------
WARNING: CPU: 1 PID: 404 at mm/page_alloc.c:4551 ......
Modules linked in:
CPU: 1 PID: 404 Comm: insmod Not tainted 6.9.0-rc5+ #123
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) ......
RIP: 0010:__alloc_pages+0x2bf/0x380
......
Call Trace:
<TASK>
? __warn+0x8e/0x150
? __alloc_pages+0x2bf/0x380
__kmalloc_large_node+0x86/0x160
__kmalloc+0x33c/0x480
virtio_fs_enqueue_req+0x240/0x6d0
virtio_fs_wake_pending_and_unlock+0x7f/0x190
queue_request_and_unlock+0x55/0x60
fuse_simple_request+0x152/0x2b0
fuse_direct_io+0x5d2/0x8c0
fuse_file_read_iter+0x121/0x160
__kernel_read+0x151/0x2d0
kernel_read+0x45/0x50
kernel_read_file+0x1a9/0x2a0
init_module_from_file+0x6a/0xe0
idempotent_init_module+0x175/0x230
__x64_sys_finit_module+0x5d/0xb0
x64_sys_call+0x1c3/0x9e0
do_syscall_64+0x3d/0xc0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
......
</TASK>
---[ end trace 0000000000000000 ]---
The warning is triggered as follows:
1) syscall finit_module() handles the module insertion and it invokes
kernel_read_file() to read the content of the module first.
2) kernel_read_file() allocates a 10MB buffer by using vmalloc() and
passes it to kernel_read(). kernel_read() constructs a kvec iter by
using iov_iter_kvec() and passes it to fuse_file_read_iter().
3) virtio-fs disables the cache, so fuse_file_read_iter() invokes
fuse_direct_io(). As for now, the maximal read size for kvec iter is
only limited by fc->max_read. For virtio-fs, max_read is UINT_MAX, so
fuse_direct_io() doesn't split the 10MB buffer. It saves the address and
the size of the 10MB-sized buffer in out_args[0] of a fuse request and
passes the fuse request to virtio_fs_wake_pending_and_unlock().
4) virtio_fs_wake_pending_and_unlock() uses virtio_fs_enqueue_req() to
queue the request. Because virtiofs need DMA-able address, so
virtio_fs_enqueue_req() uses kmalloc() to allocate a bounce buffer for
all fuse args, copies these args into the bounce buffer and passed the
physical address of the bounce buffer to virtiofsd. The total length of
these fuse args for the passed fuse request is about 10MB, so
copy_args_to_argbuf() invokes kmalloc() with a 10MB size parameter and
it triggers the warning in __alloc_pages():
if (WARN_ON_ONCE_GFP(order > MAX_PAGE_ORDER, gfp))
return NULL;
5) virtio_fs_enqueue_req() will retry the memory allocation in a
kworker, but it won't help, because kmalloc() will always return NULL
due to the abnormal size and finit_module() will hang forever.
A feasible solution is to limit the value of max_read for virtio-fs, so
the length passed to kmalloc() will be limited. However it will affect
the maximal read size for normal read. And for virtio-fs write initiated
from kernel, it has the similar problem but now there is no way to limit
fc->max_write in kernel.
So instead of limiting both the values of max_read and max_write in
kernel, introducing use_pages_for_kvec_io in fuse_conn and setting it as
true in virtiofs. When use_pages_for_kvec_io is enabled, fuse will use
pages instead of pointer to pass the KVEC_IO data.
After switching to pages for KVEC_IO data, these pages will be used for
DMA through virtio-fs. If these pages are backed by vmalloc(),
{flush|invalidate}_kernel_vmap_range() are necessary to flush or
invalidate the cache before the DMA operation. So add two new fields in
fuse_args_pages to record the base address of vmalloc area and the
condition indicating whether invalidation is needed. Perform the flush
in fuse_get_user_pages() for write operations and the invalidation in
fuse_release_user_pages() for read operations.
It may seem necessary to introduce another fie
---truncated---
CVSS Score
5.5
EPSS Score
0.0
Published
2024-12-27
In the Linux kernel, the following vulnerability has been resolved:
usb: typec: fix potential array underflow in ucsi_ccg_sync_control()
The "command" variable can be controlled by the user via debugfs. The
worry is that if con_index is zero then "&uc->ucsi->connector[con_index
- 1]" would be an array underflow.
CVSS Score
7.8
EPSS Score
0.0
Published
2024-12-27
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: MGMT: Fix slab-use-after-free Read in set_powered_sync
This fixes the following crash:
==================================================================
BUG: KASAN: slab-use-after-free in set_powered_sync+0x3a/0xc0 net/bluetooth/mgmt.c:1353
Read of size 8 at addr ffff888029b4dd18 by task kworker/u9:0/54
CPU: 1 UID: 0 PID: 54 Comm: kworker/u9:0 Not tainted 6.11.0-rc6-syzkaller-01155-gf723224742fc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Workqueue: hci0 hci_cmd_sync_work
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:93 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
q kasan_report+0x143/0x180 mm/kasan/report.c:601
set_powered_sync+0x3a/0xc0 net/bluetooth/mgmt.c:1353
hci_cmd_sync_work+0x22b/0x400 net/bluetooth/hci_sync.c:328
process_one_work kernel/workqueue.c:3231 [inline]
process_scheduled_works+0xa2c/0x1830 kernel/workqueue.c:3312
worker_thread+0x86d/0xd10 kernel/workqueue.c:3389
kthread+0x2f0/0x390 kernel/kthread.c:389
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Allocated by task 5247:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
kasan_kmalloc include/linux/kasan.h:211 [inline]
__kmalloc_cache_noprof+0x19c/0x2c0 mm/slub.c:4193
kmalloc_noprof include/linux/slab.h:681 [inline]
kzalloc_noprof include/linux/slab.h:807 [inline]
mgmt_pending_new+0x65/0x250 net/bluetooth/mgmt_util.c:269
mgmt_pending_add+0x36/0x120 net/bluetooth/mgmt_util.c:296
set_powered+0x3cd/0x5e0 net/bluetooth/mgmt.c:1394
hci_mgmt_cmd+0xc47/0x11d0 net/bluetooth/hci_sock.c:1712
hci_sock_sendmsg+0x7b8/0x11c0 net/bluetooth/hci_sock.c:1832
sock_sendmsg_nosec net/socket.c:730 [inline]
__sock_sendmsg+0x221/0x270 net/socket.c:745
sock_write_iter+0x2dd/0x400 net/socket.c:1160
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0xa72/0xc90 fs/read_write.c:590
ksys_write+0x1a0/0x2c0 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Freed by task 5246:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
poison_slab_object+0xe0/0x150 mm/kasan/common.c:240
__kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2256 [inline]
slab_free mm/slub.c:4477 [inline]
kfree+0x149/0x360 mm/slub.c:4598
settings_rsp+0x2bc/0x390 net/bluetooth/mgmt.c:1443
mgmt_pending_foreach+0xd1/0x130 net/bluetooth/mgmt_util.c:259
__mgmt_power_off+0x112/0x420 net/bluetooth/mgmt.c:9455
hci_dev_close_sync+0x665/0x11a0 net/bluetooth/hci_sync.c:5191
hci_dev_do_close net/bluetooth/hci_core.c:483 [inline]
hci_dev_close+0x112/0x210 net/bluetooth/hci_core.c:508
sock_do_ioctl+0x158/0x460 net/socket.c:1222
sock_ioctl+0x629/0x8e0 net/socket.c:1341
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:893
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83gv
entry_SYSCALL_64_after_hwframe+0x77/0x7f
CVSS Score
7.8
EPSS Score
0.0
Published
2024-12-27
In the Linux kernel, the following vulnerability has been resolved:
bnxt_en: Fix receive ring space parameters when XDP is active
The MTU setting at the time an XDP multi-buffer is attached
determines whether the aggregation ring will be used and the
rx_skb_func handler. This is done in bnxt_set_rx_skb_mode().
If the MTU is later changed, the aggregation ring setting may need
to be changed and it may become out-of-sync with the settings
initially done in bnxt_set_rx_skb_mode(). This may result in
random memory corruption and crashes as the HW may DMA data larger
than the allocated buffer size, such as:
BUG: kernel NULL pointer dereference, address: 00000000000003c0
PGD 0 P4D 0
Oops: 0000 [#1] PREEMPT SMP NOPTI
CPU: 17 PID: 0 Comm: swapper/17 Kdump: loaded Tainted: G S OE 6.1.0-226bf9805506 #1
Hardware name: Wiwynn Delta Lake PVT BZA.02601.0150/Delta Lake-Class1, BIOS F0E_3A12 08/26/2021
RIP: 0010:bnxt_rx_pkt+0xe97/0x1ae0 [bnxt_en]
Code: 8b 95 70 ff ff ff 4c 8b 9d 48 ff ff ff 66 41 89 87 b4 00 00 00 e9 0b f7 ff ff 0f b7 43 0a 49 8b 95 a8 04 00 00 25 ff 0f 00 00 <0f> b7 14 42 48 c1 e2 06 49 03 95 a0 04 00 00 0f b6 42 33f
RSP: 0018:ffffa19f40cc0d18 EFLAGS: 00010202
RAX: 00000000000001e0 RBX: ffff8e2c805c6100 RCX: 00000000000007ff
RDX: 0000000000000000 RSI: ffff8e2c271ab990 RDI: ffff8e2c84f12380
RBP: ffffa19f40cc0e48 R08: 000000000001000d R09: 974ea2fcddfa4cbf
R10: 0000000000000000 R11: ffffa19f40cc0ff8 R12: ffff8e2c94b58980
R13: ffff8e2c952d6600 R14: 0000000000000016 R15: ffff8e2c271ab990
FS: 0000000000000000(0000) GS:ffff8e3b3f840000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000000003c0 CR3: 0000000e8580a004 CR4: 00000000007706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
<IRQ>
__bnxt_poll_work+0x1c2/0x3e0 [bnxt_en]
To address the issue, we now call bnxt_set_rx_skb_mode() within
bnxt_change_mtu() to properly set the AGG rings configuration and
update rx_skb_func based on the new MTU value.
Additionally, BNXT_FLAG_NO_AGG_RINGS is cleared at the beginning of
bnxt_set_rx_skb_mode() to make sure it gets set or cleared based on
the current MTU.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-12-27
In the Linux kernel, the following vulnerability has been resolved:
s390/iucv: MSG_PEEK causes memory leak in iucv_sock_destruct()
Passing MSG_PEEK flag to skb_recv_datagram() increments skb refcount
(skb->users) and iucv_sock_recvmsg() does not decrement skb refcount
at exit.
This results in skb memory leak in skb_queue_purge() and WARN_ON in
iucv_sock_destruct() during socket close. To fix this decrease
skb refcount by one if MSG_PEEK is set in order to prevent memory
leak and WARN_ON.
WARNING: CPU: 2 PID: 6292 at net/iucv/af_iucv.c:286 iucv_sock_destruct+0x144/0x1a0 [af_iucv]
CPU: 2 PID: 6292 Comm: afiucv_test_msg Kdump: loaded Tainted: G W 6.10.0-rc7 #1
Hardware name: IBM 3931 A01 704 (z/VM 7.3.0)
Call Trace:
[<001587c682c4aa98>] iucv_sock_destruct+0x148/0x1a0 [af_iucv]
[<001587c682c4a9d0>] iucv_sock_destruct+0x80/0x1a0 [af_iucv]
[<001587c704117a32>] __sk_destruct+0x52/0x550
[<001587c704104a54>] __sock_release+0xa4/0x230
[<001587c704104c0c>] sock_close+0x2c/0x40
[<001587c702c5f5a8>] __fput+0x2e8/0x970
[<001587c7024148c4>] task_work_run+0x1c4/0x2c0
[<001587c7023b0716>] do_exit+0x996/0x1050
[<001587c7023b13aa>] do_group_exit+0x13a/0x360
[<001587c7023b1626>] __s390x_sys_exit_group+0x56/0x60
[<001587c7022bccca>] do_syscall+0x27a/0x380
[<001587c7049a6a0c>] __do_syscall+0x9c/0x160
[<001587c7049ce8a8>] system_call+0x70/0x98
Last Breaking-Event-Address:
[<001587c682c4a9d4>] iucv_sock_destruct+0x84/0x1a0 [af_iucv]
CVSS Score
5.5
EPSS Score
0.0
Published
2024-12-27
In the Linux kernel, the following vulnerability has been resolved:
PCI: Fix use-after-free of slot->bus on hot remove
Dennis reports a boot crash on recent Lenovo laptops with a USB4 dock.
Since commit 0fc70886569c ("thunderbolt: Reset USB4 v2 host router") and
commit 59a54c5f3dbd ("thunderbolt: Reset topology created by the boot
firmware"), USB4 v2 and v1 Host Routers are reset on probe of the
thunderbolt driver.
The reset clears the Presence Detect State and Data Link Layer Link Active
bits at the USB4 Host Router's Root Port and thus causes hot removal of the
dock.
The crash occurs when pciehp is unbound from one of the dock's Downstream
Ports: pciehp creates a pci_slot on bind and destroys it on unbind. The
pci_slot contains a pointer to the pci_bus below the Downstream Port, but
a reference on that pci_bus is never acquired. The pci_bus is destroyed
before the pci_slot, so a use-after-free ensues when pci_slot_release()
accesses slot->bus.
In principle this should not happen because pci_stop_bus_device() unbinds
pciehp (and therefore destroys the pci_slot) before the pci_bus is
destroyed by pci_remove_bus_device().
However the stacktrace provided by Dennis shows that pciehp is unbound from
pci_remove_bus_device() instead of pci_stop_bus_device(). To understand
the significance of this, one needs to know that the PCI core uses a two
step process to remove a portion of the hierarchy: It first unbinds all
drivers in the sub-hierarchy in pci_stop_bus_device() and then actually
removes the devices in pci_remove_bus_device(). There is no precaution to
prevent driver binding in-between pci_stop_bus_device() and
pci_remove_bus_device().
In Dennis' case, it seems removal of the hierarchy by pciehp races with
driver binding by pci_bus_add_devices(). pciehp is bound to the
Downstream Port after pci_stop_bus_device() has run, so it is unbound by
pci_remove_bus_device() instead of pci_stop_bus_device(). Because the
pci_bus has already been destroyed at that point, accesses to it result in
a use-after-free.
One might conclude that driver binding needs to be prevented after
pci_stop_bus_device() has run. However it seems risky that pci_slot points
to pci_bus without holding a reference. Solely relying on correct ordering
of driver unbind versus pci_bus destruction is certainly not defensive
programming.
If pci_slot has a need to access data in pci_bus, it ought to acquire a
reference. Amend pci_create_slot() accordingly. Dennis reports that the
crash is not reproducible with this change.
Abridged stacktrace:
pcieport 0000:00:07.0: PME: Signaling with IRQ 156
pcieport 0000:00:07.0: pciehp: Slot #12 AttnBtn- PwrCtrl- MRL- AttnInd- PwrInd- HotPlug+ Surprise+ Interlock- NoCompl+ IbPresDis- LLActRep+
pci_bus 0000:20: dev 00, created physical slot 12
pcieport 0000:00:07.0: pciehp: Slot(12): Card not present
...
pcieport 0000:21:02.0: pciehp: pcie_disable_notification: SLOTCTRL d8 write cmd 0
Oops: general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b6b: 0000 [#1] PREEMPT SMP NOPTI
CPU: 13 UID: 0 PID: 134 Comm: irq/156-pciehp Not tainted 6.11.0-devel+ #1
RIP: 0010:dev_driver_string+0x12/0x40
pci_destroy_slot
pciehp_remove
pcie_port_remove_service
device_release_driver_internal
bus_remove_device
device_del
device_unregister
remove_iter
device_for_each_child
pcie_portdrv_remove
pci_device_remove
device_release_driver_internal
bus_remove_device
device_del
pci_remove_bus_device (recursive invocation)
pci_remove_bus_device
pciehp_unconfigure_device
pciehp_disable_slot
pciehp_handle_presence_or_link_change
pciehp_ist
CVSS Score
7.8
EPSS Score
0.0
Published
2024-12-27
In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Get rid of userspace_irqchip_in_use
Improper use of userspace_irqchip_in_use led to syzbot hitting the
following WARN_ON() in kvm_timer_update_irq():
WARNING: CPU: 0 PID: 3281 at arch/arm64/kvm/arch_timer.c:459
kvm_timer_update_irq+0x21c/0x394
Call trace:
kvm_timer_update_irq+0x21c/0x394 arch/arm64/kvm/arch_timer.c:459
kvm_timer_vcpu_reset+0x158/0x684 arch/arm64/kvm/arch_timer.c:968
kvm_reset_vcpu+0x3b4/0x560 arch/arm64/kvm/reset.c:264
kvm_vcpu_set_target arch/arm64/kvm/arm.c:1553 [inline]
kvm_arch_vcpu_ioctl_vcpu_init arch/arm64/kvm/arm.c:1573 [inline]
kvm_arch_vcpu_ioctl+0x112c/0x1b3c arch/arm64/kvm/arm.c:1695
kvm_vcpu_ioctl+0x4ec/0xf74 virt/kvm/kvm_main.c:4658
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl fs/ioctl.c:893 [inline]
__arm64_sys_ioctl+0x108/0x184 fs/ioctl.c:893
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x78/0x1b8 arch/arm64/kernel/syscall.c:49
el0_svc_common+0xe8/0x1b0 arch/arm64/kernel/syscall.c:132
do_el0_svc+0x40/0x50 arch/arm64/kernel/syscall.c:151
el0_svc+0x54/0x14c arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
The following sequence led to the scenario:
- Userspace creates a VM and a vCPU.
- The vCPU is initialized with KVM_ARM_VCPU_PMU_V3 during
KVM_ARM_VCPU_INIT.
- Without any other setup, such as vGIC or vPMU, userspace issues
KVM_RUN on the vCPU. Since the vPMU is requested, but not setup,
kvm_arm_pmu_v3_enable() fails in kvm_arch_vcpu_run_pid_change().
As a result, KVM_RUN returns after enabling the timer, but before
incrementing 'userspace_irqchip_in_use':
kvm_arch_vcpu_run_pid_change()
ret = kvm_arm_pmu_v3_enable()
if (!vcpu->arch.pmu.created)
return -EINVAL;
if (ret)
return ret;
[...]
if (!irqchip_in_kernel(kvm))
static_branch_inc(&userspace_irqchip_in_use);
- Userspace ignores the error and issues KVM_ARM_VCPU_INIT again.
Since the timer is already enabled, control moves through the
following flow, ultimately hitting the WARN_ON():
kvm_timer_vcpu_reset()
if (timer->enabled)
kvm_timer_update_irq()
if (!userspace_irqchip())
ret = kvm_vgic_inject_irq()
ret = vgic_lazy_init()
if (unlikely(!vgic_initialized(kvm)))
if (kvm->arch.vgic.vgic_model !=
KVM_DEV_TYPE_ARM_VGIC_V2)
return -EBUSY;
WARN_ON(ret);
Theoretically, since userspace_irqchip_in_use's functionality can be
simply replaced by '!irqchip_in_kernel()', get rid of the static key
to avoid the mismanagement, which also helps with the syzbot issue.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-12-27
In the Linux kernel, the following vulnerability has been resolved:
KVM: arm64: Don't retire aborted MMIO instruction
Returning an abort to the guest for an unsupported MMIO access is a
documented feature of the KVM UAPI. Nevertheless, it's clear that this
plumbing has seen limited testing, since userspace can trivially cause a
WARN in the MMIO return:
WARNING: CPU: 0 PID: 30558 at arch/arm64/include/asm/kvm_emulate.h:536 kvm_handle_mmio_return+0x46c/0x5c4 arch/arm64/include/asm/kvm_emulate.h:536
Call trace:
kvm_handle_mmio_return+0x46c/0x5c4 arch/arm64/include/asm/kvm_emulate.h:536
kvm_arch_vcpu_ioctl_run+0x98/0x15b4 arch/arm64/kvm/arm.c:1133
kvm_vcpu_ioctl+0x75c/0xa78 virt/kvm/kvm_main.c:4487
__do_sys_ioctl fs/ioctl.c:51 [inline]
__se_sys_ioctl fs/ioctl.c:893 [inline]
__arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:893
__invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
el0_svc_common+0x1e0/0x23c arch/arm64/kernel/syscall.c:132
do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
el0_svc+0x38/0x68 arch/arm64/kernel/entry-common.c:712
el0t_64_sync_handler+0x90/0xfc arch/arm64/kernel/entry-common.c:730
el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:598
The splat is complaining that KVM is advancing PC while an exception is
pending, i.e. that KVM is retiring the MMIO instruction despite a
pending synchronous external abort. Womp womp.
Fix the glaring UAPI bug by skipping over all the MMIO emulation in
case there is a pending synchronous exception. Note that while userspace
is capable of pending an asynchronous exception (SError, IRQ, or FIQ),
it is still safe to retire the MMIO instruction in this case as (1) they
are by definition asynchronous, and (2) KVM relies on hardware support
for pending/delivering these exceptions instead of the software state
machine for advancing PC.
CVSS Score
5.5
EPSS Score
0.0
Published
2024-12-27