| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
KVM: SVM: Forcibly leave SMM mode on SHUTDOWN interception
Previously, commit ed129ec9057f ("KVM: x86: forcibly leave nested mode
on vCPU reset") addressed an issue where a triple fault occurring in
nested mode could lead to use-after-free scenarios. However, the commit
did not handle the analogous situation for System Management Mode (SMM).
This omission results in triggering a WARN when KVM forces a vCPU INIT
after SHUTDOWN interception while the vCPU is in SMM. This situation was
reprodused using Syzkaller by:
1) Creating a KVM VM and vCPU
2) Sending a KVM_SMI ioctl to explicitly enter SMM
3) Executing invalid instructions causing consecutive exceptions and
eventually a triple fault
The issue manifests as follows:
WARNING: CPU: 0 PID: 25506 at arch/x86/kvm/x86.c:12112
kvm_vcpu_reset+0x1d2/0x1530 arch/x86/kvm/x86.c:12112
Modules linked in:
CPU: 0 PID: 25506 Comm: syz-executor.0 Not tainted
6.1.130-syzkaller-00157-g164fe5dde9b6 #0
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS 1.12.0-1 04/01/2014
RIP: 0010:kvm_vcpu_reset+0x1d2/0x1530 arch/x86/kvm/x86.c:12112
Call Trace:
<TASK>
shutdown_interception+0x66/0xb0 arch/x86/kvm/svm/svm.c:2136
svm_invoke_exit_handler+0x110/0x530 arch/x86/kvm/svm/svm.c:3395
svm_handle_exit+0x424/0x920 arch/x86/kvm/svm/svm.c:3457
vcpu_enter_guest arch/x86/kvm/x86.c:10959 [inline]
vcpu_run+0x2c43/0x5a90 arch/x86/kvm/x86.c:11062
kvm_arch_vcpu_ioctl_run+0x50f/0x1cf0 arch/x86/kvm/x86.c:11283
kvm_vcpu_ioctl+0x570/0xf00 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4122
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x19a/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x35/0x80 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x6e/0xd8
Architecturally, INIT is blocked when the CPU is in SMM, hence KVM's WARN()
in kvm_vcpu_reset() to guard against KVM bugs, e.g. to detect improper
emulation of INIT. SHUTDOWN on SVM is a weird edge case where KVM needs to
do _something_ sane with the VMCB, since it's technically undefined, and
INIT is the least awful choice given KVM's ABI.
So, double down on stuffing INIT on SHUTDOWN, and force the vCPU out of
SMM to avoid any weirdness (and the WARN).
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
[sean: massage changelog, make it clear this isn't architectural behavior] |
| In the Linux kernel, the following vulnerability has been resolved:
net: decrease cached dst counters in dst_release
Upstream fix ac888d58869b ("net: do not delay dst_entries_add() in
dst_release()") moved decrementing the dst count from dst_destroy to
dst_release to avoid accessing already freed data in case of netns
dismantle. However in case CONFIG_DST_CACHE is enabled and OvS+tunnels
are used, this fix is incomplete as the same issue will be seen for
cached dsts:
Unable to handle kernel paging request at virtual address ffff5aabf6b5c000
Call trace:
percpu_counter_add_batch+0x3c/0x160 (P)
dst_release+0xec/0x108
dst_cache_destroy+0x68/0xd8
dst_destroy+0x13c/0x168
dst_destroy_rcu+0x1c/0xb0
rcu_do_batch+0x18c/0x7d0
rcu_core+0x174/0x378
rcu_core_si+0x18/0x30
Fix this by invalidating the cache, and thus decrementing cached dst
counters, in dst_release too. |
| In the Linux kernel, the following vulnerability has been resolved:
wifi: ath11k: add srng->lock for ath11k_hal_srng_* in monitor mode
ath11k_hal_srng_* should be used with srng->lock to protect srng data.
For ath11k_dp_rx_mon_dest_process() and ath11k_dp_full_mon_process_rx(),
they use ath11k_hal_srng_* for many times but never call srng->lock.
So when running (full) monitor mode, warning will occur:
RIP: 0010:ath11k_hal_srng_dst_peek+0x18/0x30 [ath11k]
Call Trace:
? ath11k_hal_srng_dst_peek+0x18/0x30 [ath11k]
ath11k_dp_rx_process_mon_status+0xc45/0x1190 [ath11k]
? idr_alloc_u32+0x97/0xd0
ath11k_dp_rx_process_mon_rings+0x32a/0x550 [ath11k]
ath11k_dp_service_srng+0x289/0x5a0 [ath11k]
ath11k_pcic_ext_grp_napi_poll+0x30/0xd0 [ath11k]
__napi_poll+0x30/0x1f0
net_rx_action+0x198/0x320
__do_softirq+0xdd/0x319
So add srng->lock for them to avoid such warnings.
Inorder to fetch the srng->lock, should change srng's definition from
'void' to 'struct hal_srng'. And initialize them elsewhere to prevent
one line of code from being too long. This is consistent with other ring
process functions, such as ath11k_dp_process_rx().
Tested-on: WCN6855 hw2.0 PCI WLAN.HSP.1.1-03125-QCAHSPSWPL_V1_V2_SILICONZ_LITE-3.6510.30
Tested-on: QCN9074 hw1.0 PCI WLAN.HK.2.7.0.1-01744-QCAHKSWPL_SILICONZ-1 |
| In the Linux kernel, the following vulnerability has been resolved:
net/smc: initialize close_work early to avoid warning
We encountered a warning that close_work was canceled before
initialization.
WARNING: CPU: 7 PID: 111103 at kernel/workqueue.c:3047 __flush_work+0x19e/0x1b0
Workqueue: events smc_lgr_terminate_work [smc]
RIP: 0010:__flush_work+0x19e/0x1b0
Call Trace:
? __wake_up_common+0x7a/0x190
? work_busy+0x80/0x80
__cancel_work_timer+0xe3/0x160
smc_close_cancel_work+0x1a/0x70 [smc]
smc_close_active_abort+0x207/0x360 [smc]
__smc_lgr_terminate.part.38+0xc8/0x180 [smc]
process_one_work+0x19e/0x340
worker_thread+0x30/0x370
? process_one_work+0x340/0x340
kthread+0x117/0x130
? __kthread_cancel_work+0x50/0x50
ret_from_fork+0x22/0x30
This is because when smc_close_cancel_work is triggered, e.g. the RDMA
driver is rmmod and the LGR is terminated, the conn->close_work is
flushed before initialization, resulting in WARN_ON(!work->func).
__smc_lgr_terminate | smc_connect_{rdma|ism}
-------------------------------------------------------------
| smc_conn_create
| \- smc_lgr_register_conn
for conn in lgr->conns_all |
\- smc_conn_kill |
\- smc_close_active_abort |
\- smc_close_cancel_work |
\- cancel_work_sync |
\- __flush_work |
(close_work) |
| smc_close_init
| \- INIT_WORK(&close_work)
So fix this by initializing close_work before establishing the
connection. |
| In the Linux kernel, the following vulnerability has been resolved:
loop: Fix use-after-free issues
do_req_filebacked() calls blk_mq_complete_request() synchronously or
asynchronously when using asynchronous I/O unless memory allocation fails.
Hence, modify loop_handle_cmd() such that it does not dereference 'cmd' nor
'rq' after do_req_filebacked() finished unless we are sure that the request
has not yet been completed. This patch fixes the following kernel crash:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000054
Call trace:
css_put.42938+0x1c/0x1ac
loop_process_work+0xc8c/0xfd4
loop_rootcg_workfn+0x24/0x34
process_one_work+0x244/0x558
worker_thread+0x400/0x8fc
kthread+0x16c/0x1e0
ret_from_fork+0x10/0x20 |
| In the Linux kernel, the following vulnerability has been resolved:
bpf: fix potential 32-bit overflow when accessing ARRAY map element
If BPF array map is bigger than 4GB, element pointer calculation can
overflow because both index and elem_size are u32. Fix this everywhere
by forcing 64-bit multiplication. Extract this formula into separate
small helper and use it consistently in various places.
Speculative-preventing formula utilizing index_mask trick is left as is,
but explicit u64 casts are added in both places. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/vc4: hdmi: Move packet RAM enable to PM runtime
Audio can be triggered by the HPD handler and start up before video has
been restored, calling vc4_hdmi_write_infoframe() for the audio infoframe.
vc4_hdmi_write_infoframe() needs Packet RAM to be on to store the
infoframe, however, if the video hasn't been enabled,
vc4_hdmi_encoder_post_crtc_enable() hasn't been called and therefore, the
Packet RAM can be disabled by the time vc4_hdmi_write_infoframe() executes,
causing the following splat:
[ 201.570266] ------------[ cut here ]------------
[ 201.570293] Packet RAM has to be on to store the packet.
[ 201.570367] WARNING: drivers/gpu/drm/vc4/vc4_hdmi.c:683 at vc4_hdmi_write_infoframe+0x404/0x494 [vc4], CPU#0: wireplumber/1606
[...]
[ 201.658650] Hardware name: Raspberry Pi 4 Model B Rev 1.5 (DT)
[...]
[ 201.758499] Call trace:
[ 201.760967] vc4_hdmi_write_infoframe+0x404/0x494 [vc4] (P)
[ 201.766607] vc4_hdmi_write_audio_infoframe+0x1c/0x28 [vc4]
[ 201.772247] write_infoframe+0xbc/0x140 [drm_display_helper]
[ 201.777975] drm_atomic_helper_connector_hdmi_update_audio_infoframe+0x80/0xdc [drm_display_helper]
[ 201.787140] vc4_hdmi_audio_prepare+0x4ac/0x570 [vc4]
[ 201.792252] drm_connector_hdmi_audio_prepare+0x24/0x30 [drm_display_helper]
[ 201.799390] hdmi_codec_prepare+0x100/0x160 [snd_soc_hdmi_codec]
[ 201.805471] snd_soc_pcm_dai_prepare+0xd4/0x100 [snd_soc_core]
[ 201.811375] __soc_pcm_prepare+0x60/0x12c [snd_soc_core]
[ 201.816752] soc_pcm_prepare+0x34/0x58 [snd_soc_core]
[ 201.821863] snd_pcm_do_prepare+0x70/0x8c [snd_pcm]
[ 201.826798] snd_pcm_action_nonatomic+0xe4/0x174 [snd_pcm]
[ 201.832350] snd_pcm_prepare+0xc8/0xd8 [snd_pcm]
[ 201.837021] snd_pcm_common_ioctl+0x458/0x614 [snd_pcm]
[ 201.842308] snd_pcm_ioctl+0x30/0x48 [snd_pcm]
[ 201.846802] __arm64_sys_ioctl+0x88/0xd8
[ 201.850769] invoke_syscall+0x48/0xf4
[ 201.854470] el0_svc_common+0x80/0xd8
[ 201.858171] do_el0_svc+0x1c/0x28
[ 201.861520] el0_svc+0x3c/0xb0
[ 201.864605] el0t_64_sync_handler+0x68/0xdc
[ 201.868834] el0t_64_sync+0x198/0x19c
[ 201.872536] ---[ end trace 0000000000000000 ]---
Considering that Packet RAM enable is essentially a power management
configuration, move its enabling/disabling to the Runtime PM hooks.
Note that post_crtc_disable() still stops all infoframes, but keeps Packet
RAM enabled, leaving it to be disabled by runtime suspend. |
| In the Linux kernel, the following vulnerability has been resolved:
netlink: reset skb headers before unicast and multicast filtering
Socket filters can use SKF_NET_OFF and SKF_LL_OFF to read relative to
an skb's network and MAC headers. Netlink producers may reserve
headroom without resetting those headers, allowing a receiving socket's
filter to read data before the initialized message.
For example, IWPM HELLO replies are allocated with dev_alloc_skb(),
which reserves NET_SKB_PAD bytes. An unprivileged NETLINK_RDMA user can
attach a classic socket filter and disclose this headroom through the
length of the delivered reply. The resets in netlink_dump() do not help
because IWPM sends a separately allocated skb through netlink_unicast().
Reset both headers before running the receiver's filter in unicast and
broadcast delivery, as is already done for dump skbs. This also covers
other netlink producers that reserve headroom without changing their
allocation or message-building code. |
| In the Linux kernel, the following vulnerability has been resolved:
scsi: target: iscsi: Fix race in discovery auth updates
Separate configfs opens can concurrently update the discovery AuthMethod
parameter. Both callers may free the same value in
iscsi_update_param_value(), causing a double-free.
Protect the lookup and replacement with the discovery TPG access lock,
as used by the other TPG configfs parameter updates. |
| In the Linux kernel, the following vulnerability has been resolved:
ocfs2/dlm: Protect the recovery list during debugfs reads
Recovery participant records must remain alive while debug_state_print()
walks reco.node_data and formats their fields. The formatter holds
dlm->spinlock, but the recovery participant list is protected by
dlm_reco_state_lock. In particular, dlm_destroy_recovery_area() detaches
the list under dlm_reco_state_lock and frees the detached records after
releasing it. A concurrent debugfs open can therefore read freed memory.
Protect the participant traversal and field reads in debug_state_print()
with dlm_reco_state_lock, matching the existing list writers. This also
serializes the traversal against list_add_tail() during recovery-area
initialization. Make the existing lock available to the debug code
through dlmcommon.h; the lock remains internal to the OCFS2 DLM module.
Release dlm->spinlock after formatting the other domain state and before
acquiring dlm_reco_state_lock, so the debug reader does not nest the two
locks. Leave recovery list insertion, detachment and freeing unchanged.
KASAN report as below:
BUG: KASAN: slab-use-after-free in debug_state_open+0x1169/0x12d0
Read of size 4 at addr ffff88810662ef80 by task dlm-state-stres/896
CPU: 1 UID: 0 PID: 896 Comm: dlm-state-stres Not tainted 7.3.0-rc4-next-20260921-pmb-ocfs2-functional-v1+ #1 PREEMPT(lazy)
Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x93/0xd0
print_report+0xce/0x630
? debug_state_open+0x1169/0x12d0
? srso_alias_return_thunk+0x5/0xfbef5
? __virt_addr_valid+0x20e/0x420
? debug_state_open+0x1169/0x12d0
kasan_report+0xe0/0x110
? debug_state_open+0x1169/0x12d0
debug_state_open+0x1169/0x12d0
? __pfx_debug_state_open+0x10/0x10
full_proxy_open_regular+0x193/0x310
do_dentry_open+0x595/0x12d0
? __pfx_full_proxy_open_regular+0x10/0x10
vfs_open_consume+0xd1/0x400
? srso_alias_return_thunk+0x5/0xfbef5
path_openat+0x18d0/0x2020
? __pfx_path_openat+0x10/0x10
do_file_open+0x21e/0x470
? __pfx_do_file_open+0x10/0x10
? _raw_spin_unlock+0x23/0x40
? srso_alias_return_thunk+0x5/0xfbef5
? alloc_fd+0x3a6/0x6b0
do_sys_openat2+0xf4/0x1b0
? __pfx_do_sys_openat2+0x10/0x10
? srso_alias_return_thunk+0x5/0xfbef5
? __fput+0x5b5/0xa60
__x64_sys_openat+0x136/0x1e0
? __pfx___x64_sys_openat+0x10/0x10
do_syscall_64+0x114/0x620
entry_SYSCALL_64_after_hwframe+0x77/0x7f
[Register dump omitted.]
</TASK>
Allocated by task 880:
kasan_save_stack+0x33/0x60
kasan_save_track+0x14/0x30
__kasan_kmalloc+0xaa/0xb0
__kmalloc_cache_noprof+0x28d/0x610
dlm_remaster_locks+0x147/0x1d90
dlm_do_recovery+0xde1/0x1580
dlm_recovery_thread+0x109/0x300
kthread+0x351/0x460
ret_from_fork+0x659/0x940
ret_from_fork_asm+0x1a/0x30
Freed by task 880:
kasan_save_stack+0x33/0x60
kasan_save_track+0x14/0x30
kasan_save_free_info+0x3b/0x60
__kasan_slab_free+0x5f/0x80
kfree+0x308/0x580
dlm_destroy_recovery_area+0x285/0x460
dlm_remaster_locks+0x17c4/0x1d90
dlm_do_recovery+0xde1/0x1580
dlm_recovery_thread+0x109/0x300
kthread+0x351/0x460
ret_from_fork+0x659/0x940
ret_from_fork_asm+0x1a/0x30
The buggy address belongs to the object at ffff88810662ef80
which belongs to the cache kmalloc-32 of size 32
The buggy address is located 0 bytes inside of
freed 32-byte region [ffff88810662ef80, ffff88810662efa0)
[Page and memory-state dumps omitted.] |
| In the Linux kernel, the following vulnerability has been resolved:
netlink: avoid hashing the network namespace pointer
The netlink rhashtable key includes a raw struct net pointer and a
user-controlled port ID. Both /proc/net/netlink and socket diagnostics
expose the table's bucket order. By binding and rebinding chosen
NETLINK_USERSOCK port IDs, an unprivileged reader can distinguish equal
buckets and recover the low bits of the Jenkins hash. Its 32-bit seed
and the limited set of kernel-image slides can then be searched offline
to recover the address of init_net.
Use the namespace's unique, non-address net_cookie in the comparison
key instead. It is assigned before the per-net initializers run and
remains unchanged for the namespace's lifetime. The lookup key and
object hash are still built by netlink_compare_arg_init(), keeping
lookup, insertion, removal and rehashing consistent while preserving
namespace separation. Neither public table walker needs to change.
Reading the socket's namespace cookie in netlink_compare() is safe
under RCU, including during namespace teardown. netlink_release()
removes the socket from the hash table and defers its final put with
call_rcu(). cleanup_net() runs the per-net exit methods and waits for
outstanding RCU callbacks with rcu_barrier() before freeing namespace
storage.
Unlike ns.ns_id, net_cookie is also available and initialized during
setup_net() in older stable kernels, making the change straightforward
to backport to v5.15 and later. |
| In the Linux kernel, the following vulnerability has been resolved:
calipso: keep BIG TCP payload_len in calipso_skbuff_setattr()
calipso_skbuff_setattr() adjusts payload_len by the length of the
option it inserts or resizes:
payload = ntohs(ip6_hdr->payload_len);
ip6_hdr->payload_len = htons(payload + len_delta);
GRO can build BIG TCP packets larger than IPV6_MAXPLEN, and stores
payload_len == 0 for them; ipv6_payload_len() then falls back to
skb->len. For such a packet forwarded to a destination mapped to
CALIPSO, the code above writes len_delta (or 65536 + len_delta when
shrinking) into payload_len, and ipv6_payload_len() no longer falls
back to skb->len. nf_tables, conntrack and sch_cake rely on it.
The same arithmetic also wraps when a packet grows past IPV6_MAXPLEN,
and a BIG TCP packet that shrinks below IPV6_MAXPLEN should get its
real length back.
Set payload_len from the skb length with ipv6_set_payload_len(), which
stores 0 above IPV6_MAXPLEN and the real length otherwise, as
ipv6_gro_complete() does. The network header was just reset to
skb->data, so skb->len - sizeof(*ip6_hdr) is the payload length.
Tested on one kernel (arm64, QEMU) with SELinux permissive, a minimal
mdp-generated policy (network_peer_controls=1), "netlabelctl calipso
add pass doi:16" and a NetLabel mapping of fd00:2::/64 to CALIPSO
DOI 16. calipso_skbuff_setattr() was called through
netlbl_skbuff_setattr() from a test-only debugfs hook (not part of
this patch) adding a level-only label; payload_len after the call:
case before fix after fix real length
1000, unlabeled 1016 1016 1016
70000 GSO, payload_len 0 16 0 70016
65530 GSO, grows past MAXPLEN 10 0 65546
65540 GSO with a 24 byte hop
header, shrinks below MAXPLEN 65528 65532 65532
1000 with a 24 byte hop header 992 992 992
(0 means ipv6_payload_len() returns the real length.) On the forward
path, with a client injecting unlabeled UDP through a router to a
server, the router adds the CALIPSO option and the server delivers all
datagrams (Udp6InDatagrams 5, Ip6InTruncatedPkts 0) with this patch. |
| In the Linux kernel, the following vulnerability has been resolved:
gpiolib: fix memory leak in gpiod_set_array_value_complex() on error paths
A drive-by review by Sashiko reports that, after a failed call to
gpiochip_set_multiple(), gpiod_set_array_value() returns abruptly,
bypassing the freeing of possibly alloced bitmaps, potentially leaking
memory. It is an unlikely error path, but is possible.
Defer the return code check until after the bitmap_free() block. |
| In the Linux kernel, the following vulnerability has been resolved:
ASoC: SOF: ipc4-topology: Fix shift-out-of-bounds for aggregated ALH capture
When ch_count is smaller than blob->alh_cfg.device_count (e.g. a mono
capture stream, such as a SmartMic, aggregated across multiple SDW
links), step = ch_count / blob->alh_cfg.device_count truncates to 0.
The subsequent GENMASK(step - 1, 0) then underflows step - 1 (u32) to
UINT_MAX, causing GENMASK()'s internal shift to use an out-of-bounds
exponent:
UBSAN: shift-out-of-bounds in sound/soc/sof/ipc4-topology.c:2363:13
shift exponent 18446744069414584384 is too large for 64-bit type 'long unsigned int'
Treat ch_count < device_count the same way as the existing "channels
equal to output reference channels" case: apply the same ch_mask to
every aggregated device instead of trying to split channels that
can't be evenly divided. |
| In the Linux kernel, the following vulnerability has been resolved:
watch_queue: Fix note pool publication race in watch_queue_set_size()
There is a race between watch_queue_set_size() and post_one_notification().
watch_queue_set_size() publishes wqueue->notes, notes_bitmap, nr_pages and
nr_notes with plain stores, and post_one_notification() reads them with
plain loads under a different lock, so nothing orders the four stores
against the poster's loads: depending on the build, notes can be stored
last (gcc 14 on x86-64 does this). Since keyctl_watch_key() lets a watch
attach to a queue before it is sized, post_one_notification() can already
be running on another CPU at that moment: it reads nr_notes > 0, passes
its bounds check, and then reads notes while it is still NULL,
dereferencing notes[0].
An unprivileged user triggers this reliably by watching one of its own
keys through a notification pipe and racing ioctl(IOC_WATCH_QUEUE_SET_SIZE)
on that pipe against keyctl(KEYCTL_SETPERM) on the key from another CPU,
triggering:
BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:post_one_notification.isra.0+0xa2/0x1e0
Call Trace:
__post_watch_notification+0x148/0x180
keyctl_setperm_key+0x119/0x130
do_syscall_64+0x108/0x4c0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Kernel panic - not syncing: Fatal exception in interrupt
Fix this by publishing nr_notes last with smp_store_release(), and by
reading it once with smp_load_acquire() in post_one_notification() before
the bitmap and the page array are touched. A poster that observes a
non-zero nr_notes then also observes the pool behind it; one that observes
zero drops the notification as before. |
| In the Linux kernel, the following vulnerability has been resolved:
x86/kvm: Don't consume async #PF flags on a kernel #PF in NMI context
An async #PF "page not present" event arrives through the #PF vector,
and its reason sits in the per-CPU apf_reason.flags until
__kvm_handle_async_pf() reads and clears it. If an NMI arrives after
the event is injected and before the #PF handler reads the flags, and
the NMI handler itself takes a #PF, that fault reads and clears the
flags belonging to the #PF it interrupted. It then finds interrupts
disabled in the NMI context it interrupted, and panics:
Kernel panic - not syncing: Host injected async #PF in interrupt
disabled region
Call Trace:
<NMI>
panic+0x52/0x60
__kvm_handle_async_pf+0xb0/0xb0
exc_page_fault+0x71/0xb0
asm_exc_page_fault+0x27/0x30
RIP: 0010:__get_user_nocheck_8+0x6/0x20
perf_callchain_user+0x147/0x1a0
get_perf_callchain+0x12d/0x1c0
...
perf_event_nmi_handler+0x26/0x50
exc_nmi+0xe8/0x110
RIP: 0010:asm_exc_page_fault+0x0/0x30
</NMI>
The last RIP line shows the NMI landing on the first instruction of
the #PF entry. perf with user call chains takes such a fault: the
sampling NMI walks the user stack with __get_user(), which faults when
a saved frame pointer is not a valid user address or the walk runs off
the top of the stack. The same window exists when KVM, running as an
L1 hypervisor with DELIVERY_AS_PF_VMEXIT, reads the flags itself after
a #PF VM-exit.
The NMI entry code saves and restores CR2 for this nesting, but not the
async #PF reason. Andy Lutomirski described the race, with perf as the
example, when async #PF delivery was reworked in 2020 [1]. Saving and
clearing the flags across the NMI, next to CR2, was discussed there but
not merged.
Since that rework, Linux has stopped setting KVM_ASYNC_PF_SEND_ALWAYS,
so the host delivers "page not present" only for user mode faults and
a kernel-mode fault in NMI context (including kernel-mode #MC and #DB)
cannot be an async page fault. In that case, return without touching
the flags so that the interrupted handler finds them intact.
Tested on v7.3-rc5 in a 4-vCPU, 2 GiB guest restored from a snapshot
whose memory is served on demand through userfaultfd, so that reading
it back takes async #PFs, while every thread samples hardware cycles
with user call chains and points its frame pointer at an unmapped page.
Without this patch the guest panicked as above in 3 of 3 runs. With it,
the guest survived 3 of 3 runs of 60 seconds, and the host counted
148,441 to 153,334 kvm_async_pf_not_present events in the first 20
seconds of each. On 6.18.50 the results were the same: the guest
panicked without the patch and survived with it. |
| In the Linux kernel, the following vulnerability has been resolved:
KVM: nVMX: Reset MMU back to the root MMU if loading L2 state fails for !VM-Entry
Reset the vCPU's MMU pointer back to the root MMU if loading L2 state fails
in the "not from VM-Entry" case, i.e. when emulating RSM or handling
KVM_SET_NESTED_STATE. Failure to unwind the MMU pointer results in KVM
trying to run L1 with a nested MMU, and is especially problematic if the
vCPU manages to free its nested state before the VM crashes. Constructing
the root for a nested EPT MMU goes through vmcs12, which is dynamically
allocated/freed when nVMX is enabled/disabled. And so if the nested state
is freed with the MMU still pointing at the nested MMU, KVM will hit a NULL
pointer deref when attempting to get L1=>L2 EPTP.
BUG: kernel NULL pointer dereference, address: 0000000000000078
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 114a2d067 P4D 111743067 PUD 11141f067 PMD 0
Oops: Oops: 0000 [#1] SMP
CPU: 20 UID: 1000 PID: 1272 Comm: nested_tdp_faul Not tainted 7.3.0-rc4-8c89f11d1a99b-sink-vm #1914 PREEMPTLAZY
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel]
Call Trace:
<TASK>
kvm_mmu_load+0xcd/0x870 [kvm]
kvm_arch_vcpu_ioctl_run+0x18f5/0x1f80 [kvm]
kvm_vcpu_ioctl+0x2c7/0x970 [kvm]
__x64_sys_ioctl+0x90/0xd0
do_syscall_64+0x9c/0x4d0
entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x47491b
</TASK>
Modules linked in: kvm_intel kvm irqbypass
CR2: 0000000000000078
---[ end trace 0000000000000000 ]---
RIP: 0010:nested_ept_get_eptp+0xb/0x10 [kvm_intel]
[sean: write changelog] |
| In the Linux kernel, the following vulnerability has been resolved:
fsnotify: prevent mark additions during connector teardown
fsnotify_destroy_marks() keeps a reference to its current mark while it
drops conn->lock to destroy the mark. This stabilizes the forward-walk
cursor, but does not prevent a new mark from being inserted before it.
For example, an inotify watch re-added after IN_IGNORED sorts before the
old, detached mark for the same group. The walk can miss the replacement
and then detach the entire connector from the object.
The replacement is still on its group's marks_list and, for inotify, in
the watch IDR. The group mutex no longer protects the connector's object
from disappearing. An unprivileged fdinfo read racing the final detach
can consequently call igrab(NULL):
BUG: KASAN: null-ptr-deref in igrab+0x24/0x100
Write of size 4 at addr 0000000000000148
Call Trace:
igrab+0x24/0x100
inotify_show_fdinfo+0x1dc/0x5e0
seq_show+0x397/0x690
Set a DESTROYING flag under conn->lock before starting the walk, and
reject new marks on that connector with -ENOENT. The existing add-mark
error paths undo the temporary group-list entry and the backend's watch
allocation. Do not wait for teardown while holding the group mutex,
which the destroyer needs. Once the old connector is detached, an add
can install a fresh connector as before.
This closes the insertion race for all object types using the common
connector teardown, without changing the mark reference or SRCU lifetime
rules. |
| In the Linux kernel, the following vulnerability has been resolved:
ext4: free the sbi after a grace period
ext4_get_link() follows a symlink that keeps its target in a data block
in rcu pathwalk mode with ext4_getblk(EXT4_GET_BLOCKS_CACHED_NOWAIT).
That reads s_mount_state in the ASSERT() of ext4_getblk() and again in
ext4_es_lookup_extent(), and the lookup bumps the extent status hit or
miss counter, all through sb->s_fs_info.
ext4_put_super() destroys those counters, clears sb->s_fs_info and frees
the sbi without waiting for a grace period. A pathwalk that is still in
ext4_get_link() when the last reference to the mount goes away then
dereferences a NULL s_fs_info, the freed sbi or the destroyed percpu
counters.
With a pathwalk held up in ext4_get_link() while the last reference
goes away:
KASAN: null-ptr-deref in range [0x00000000000000a8-0x00000000000000af]
RIP: 0010:ext4_getblk+0xf0/0x640
Call Trace:
<TASK>
ext4_get_link+0x26c/0x410
pick_link+0xf96/0x1780
step_into_slowpath+0x9b8/0x1250
path_lookupat+0x484/0xb00
filename_lookup+0x1f1/0x5b0
vfs_statx+0xd7/0x3b0
vfs_fstatat+0x4d/0x90
__do_sys_newfstatat+0xa0/0x100
do_syscall_64+0x10e/0x5e0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
So far that has been hard to hit. umount(2) waits for a grace period in
namespace_unlock() before it drops the mount, so only a mount whose last
reference goes away elsewhere, like the close of a file or a chdir out of
a lazily unmounted directory, can race a walker.
Keep sb->s_fs_info and free the sbi together with the extent status
counters after a grace period. Split the counters out of
ext4_es_unregister_shrinker() for that. The shrinker still gets wasted
in ext4_put_super(), the counters go with the sbi. |
| In the Linux kernel, the following vulnerability has been resolved:
ntfs3: free the sbi after a grace period
If the "nocase" mount option ntfs3 uses custom hash and dentry compare
functions. Both access ntfs3 superblock private information in rcu
pathwalk. ntfs_put_super() and ntfs3_kill_sb() drop the info without any
rcu delay. A lookup that's still inside the filesystem when the last
reference to the mount is dropped causes a UAF. With a pathwalk held up
in ntfs_d_hash() while the last reference to the mount goes away:
BUG: KASAN: slab-use-after-free in ntfs_nls_to_utf16+0x752/0x940
Read of size 8 at addr ff1100010453c850 by task walker/99
Call Trace:
<TASK>
ntfs_nls_to_utf16+0x752/0x940
ntfs_d_hash+0x22b/0x500
link_path_walk+0x11ad/0x1d30
path_lookupat+0x63/0xb00
filename_lookup+0x1f1/0x5b0
vfs_statx+0xd7/0x3b0
[...]
Allocated by task 95:
__kmalloc_cache_noprof+0x249/0x560
ntfs_init_fs_context+0x2db/0x5a0
alloc_fs_context+0x52e/0xc70
[...]
Freed by task 98:
kfree+0x1db/0x5b0
deactivate_locked_super+0x9c/0xf0
cleanup_mnt+0x9f/0x130
task_work_run+0x131/0x250
The bug is currently masked by the grace period in namespace_unlock()
for umount(2). Keep the necessary information until the filesystem
private info is freed and free it with an rcu delay.
ntfs3_free_sbi() now runs from an rcu callback and drops the upcase
table via ntfs_put_shared(). So switch s_shared_lock over to
spin_lock_bh(). Otherwise the callback can deadlock against a task
holding the lock on the same cpu. |
