| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: SCO: serialise sco_conn lifetime against sco_recv_scodata()
sco_recv_scodata() upgrades the weak hcon->sco_data back-pointer to a
strong reference under hdev->lock:
hci_dev_lock(hdev);
hcon = hci_conn_hash_lookup_handle(hdev, handle);
...
conn = sco_conn_hold_unless_zero(hcon->sco_data);
hci_dev_unlock(hdev);
but the pointer is cleared from the other side without that lock. When
the last sco_conn reference is dropped, sco_conn_free() ran
conn->hcon->sco_data = NULL;
with no hdev->lock held, so the RX path could read hcon->sco_data and
call kref_get_unless_zero() on an sco_conn that was concurrently freed:
BUG: KASAN: slab-use-after-free in sco_conn_hold_unless_zero+0xbe/0x160
Write of size 4 by task kworker/u17:0
Workqueue: hci0 hci_rx_work
Call Trace:
sco_conn_hold_unless_zero+0xbe/0x160
sco_recv_scodata+0x13f/0x490
hci_rx_work+0x3af/0x730
kref_get_unless_zero() only guards against a zero refcount, not against
the backing memory already being freed.
Give hcon->sco_data an actual reference on the sco_conn it points to, so
the object cannot be freed while the pointer is still installed, and only
clear and drop it from sco_conn_del(), which runs under hdev->lock (its
callers, sco_connect_cfm() and sco_disconn_cfm(), hold it). The reader in
sco_recv_scodata() also takes hdev->lock, so the store and the read are
now serialised: the RX path either observes NULL or a reference that is
guaranteed to stay valid until it drops its own.
sco_conn_add() no longer hands its kref_init() reference to the caller as
the connection's only reference; that initial reference is the one owned
by hcon->sco_data, and callers get their own via sco_conn_hold().
Because the sco_conn can now outlive the socket (the association keeps it
alive until the link goes down), the hci_conn can no longer be dropped
from sco_conn_free() without regressing socket close: closing a connected
SCO socket must still tear the link down. Move hci_conn ownership to the
socket instead: __sco_chan_add() takes an hci_conn reference and it is
released from sco_chan_del() and sco_sock_destruct(), exactly once. The
sco_conn no longer owns an hci_conn reference, so sco_conn_add() stops
consuming one and sco_connect() drops the hci_connect_sco() reference on
every path; sco_connect_cfm() no longer needs its hci_conn_hold() dance. |
| In the Linux kernel, the following vulnerability has been resolved:
gpio: mpsse: fix race when arming the IRQ poll worker
gpio_mpsse_irq_enable() arms the poll worker before publishing it:
schedule_work() runs before the worker is added to priv->workers. If
gpio_mpsse_disconnect() walks the list in that window it misses the
worker, and once disconnect returns, the USB core frees mpsse_priv
while the orphaned gpio_mpsse_poll() work keeps accessing it, causing
a use-after-free.
Fix this by publishing and arming the worker in one irq_spin
critical section. Teardown walks the same list under irq_spin, so a
worker found on the list is guaranteed to be armed, and
cancel_work_sync() handles it whether it is queued or running.
A worker armed after the disconnect walk would still be missed, so
also set a new priv->dying flag under irq_spin before the teardown
walk, and check it in the same critical section, freeing it via
kfree_rcu() instead when the device is going away, since kfree()
would be called with the IRQ core's raw spinlock held and may sleep
on PREEMPT_RT. schedule_work() is safe to call with irq_spin held,
and the next probe gets a fresh mpsse_priv, so the flag never needs
to be cleared.
This issue was found by an in-house static analysis tool. |
| In the Linux kernel, the following vulnerability has been resolved:
EDAC/altera: Fix use-after-free in error paths
In both altr_edac_a10_device_add() and altr_portb_setup(), the error path
freed the dci structure before releasing the devres group. Since the managed
single and double bit IRQ handlers use altdev(dci->pvt_info) as their data, an
IRQ firing between freeing dci and unregistering the IRQs could dereference
the freed memory.
Release the devres group first so the managed IRQs are unregistered
before the dci structure is freed. |
| In the Linux kernel, the following vulnerability has been resolved:
namespace: reset the old parent's ->overmount in mnt_change_mountpoint()
__umount_mnt() resets ->overmount of the parent when it unmounts the
mount that overmounts it. mnt_change_mountpoint() doesn't. It moves the
mount to its new parent and leaves the old one pointing at it.
For a mount that is moved beneath in attach_recursive_mnt() that doesn't
matter. The new mount has already reset ->overmount of the old parent by
the time the old top mount is moved onto it.
It matters for reparent() though. propagate_umount() moves a surviving
overmount onto the first ancestor that isn't going to be unmounted. The
mount it was taken from is unmounted immediately afterwards. If a file
descriptor keeps that unmounted mount alive ->overmount points at the
moved mount. That's a dangling pointer and UAF as the moved mount is
unmounted and freed.
do_lock_mount() follows ->overmount from the target path under
mount_lock. With a file descriptor on such a mount as the target of a
mount beneath topmost_overmount() walks into the freed mount and
do_lock_mount() takes references on whatever it finds there.
So reset ->overmount of the old parent in mnt_change_mountpoint() the
same way __umount_mnt() does. A mount's ->overmount is then always a
mount that is attached to it. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/xe: Fix stale pinned_link entry when fb-pin performs the final unpin
xe_bo_pin_external() and xe_bo_unpin_external() maintain the bo's
pinned_link list membership in xe->pinned.late.external, based on
whether the current call is the outermost pin or the final unpin.
However, the same external bo's pin_count can also be raised and
lowered directly by __xe_pin_fb_vma()/__xe_unpin_fb_vma(), which pin
the bo as a display scanout buffer without going through
xe_bo_pin_external()/xe_bo_unpin_external() at all, and have no
notion of, or ownership over, pinned_link.
If a bo is pinned both externally (e.g. dma-buf export) and as an fb,
and the external unpin happens first, xe_bo_unpin_external() correctly
observes pin_count > 1 and leaves the bo on pinned_link. When the fb
unpin later performs the true last unpin (pin_count 1 -> 0), it never
touches pinned_link, leaving the bo linked on xe->pinned.late.external
indefinitely. Once the bo is subsequently freed, this stale list entry
points into freed memory, corrupting the list and risking a
use-after-free the next time the list is walked or spliced.
The backup object pin/unpin sites in xe_bo_notifier_prepare_pinned()/
xe_bo_notifier_unprepare_pinned() have the same bypass characteristic,
though they never add their bo to a pinned list, so are not affected
by this particular list-corruption issue.
Move the pinned_link removal into xe_bo_account_unpin(), which already
runs on every unpin path (kernel, external, framebuffer, backup
object) right before the true 1 -> 0 pin_count transition. Since
list_del_init() only operates on the node itself, this removal is
list-agnostic and safe to perform regardless of which list (external
or kernel_bo_present) the bo happens to be linked on, or which code
path is performing the final unpin. Drop the now-redundant explicit
list_del_init() calls in xe_bo_unpin_external() and xe_bo_unpin().
v2:
- New patch
v3:
- Rebased on changes to previous patch.
(cherry picked from commit ca58d36a1f93af586ee93b340c9f9fd81312cc01) |
| In the Linux kernel, the following vulnerability has been resolved:
HID: alps: fix use-after-free on input2 registration failure
alps_input_configured() stores data->input2 before calling
input_register_device(). If registration fails, input_free_device()
frees the input device but data->input2 still points to the freed memory.
alps_input_configured() calls hid_hw_open() before allocating input2, so
URBs are already active and raw_event can fire during the failure window.
A U1_SP_ABSOLUTE_REPORT_ID report arriving then causes u1_raw_event()
to dereference the freed data->input2 -> use-after-free.
Fix by only storing input2 into drvdata after successful registration
and adding a NULL guard in the raw_event path. |
| In the Linux kernel, the following vulnerability has been resolved:
amt: send the relay's General Query directly from the receive path
An skb queued in a qdisc can outlive the tunnel it references
through a raw pointer in skb->cb. For example, with igmp_qrv set
to 1 on the relay a tunnel lives for 135s, so a netem delay of
180s on the amt device outlives it; when the tunnel expires and is
freed, the subsequent dequeue triggers a use-after-free in
amt_dev_xmit().
BUG: KASAN: slab-use-after-free in amt_dev_xmit+0x2763/0x2e20
Call Trace:
amt_dev_xmit+0x2763/0x2e20 [drivers/net/amt.c:1262]
dev_hard_start_xmit+0x22f/0x620
sch_direct_xmit+0x12e/0xac0
netem_dequeue+0x333/0xc50
net_tx_action+0x35c/0xa60
amt_send_igmp_gq() and amt_send_mld_gq() are only called from
amt_request_handler(), inside the rcu_read_lock_bh() section of
amt_rcv(). amt_request_handler() already has the tunnel the query is
for: it found or created it inside that section. Queuing the query with
dev_queue_xmit() only leads back into amt_dev_xmit(), which strips the
Ethernet header and calls amt_send_membership_query() for that tunnel.
Make that call directly from the two senders instead, the same way
amt_send_advertisement() transmits from the receive path. The query
never waits in a qdisc, the tunnel is only dereferenced inside the
RCU section that found or created it, and nothing is stored in
skb->cb, so no lookup or refcount is needed. Remove the query branch
of amt_dev_xmit(), amt_skb_cb() and struct amt_skb_cb, which have no
users left.
Behaviour changes:
- The relay's own General Queries no longer pass through the amt
device's egress path: its qdisc, tc egress (clsact/tcx), the
netfilter egress hook and packet taps. They are still visible as
UDP on the underlay.
- A query that is sent successfully is no longer counted as
tx_dropped. The old query branch left through the unlock label,
which counted every sent query as dropped.
- A query that reaches amt_dev_xmit() on a relay from elsewhere,
such as a userspace querier, is now dropped at the IGMP/MLD type
switch. Before, it trusted whatever skb->cb held, and a NULL
tunnel hit the WARN_ON(1). |
| In the Linux kernel, the following vulnerability has been resolved:
bpf: Skip unsettled links in link iterator
bpf_link_prime() inserts a link into link_idr before anon_inode_getfile()
succeeds and before bpf_link_settle() publishes the ID in link->id.
bpf_link_by_id() treats such an ID-zero link as unsettled, but the link
iterator takes a reference without this check.
If anon_inode_getfile() then fails, the creator removes the ID and frees
its still-private link directly. The iterator is left with a dangling
reference and its next bpf_link_put() accesses freed memory.
Treat ID-zero entries as transient in bpf_link_get_curr_or_next(), just as
bpf_link_by_id() does.
BUG: KASAN: slab-use-after-free in bpf_link_put
Write of size 8 by task exp/384
Call Trace:
bpf_link_put kernel/bpf/syscall.c:3372
bpf_link_seq_next kernel/bpf/link_iter.c:33
bpf_seq_read kernel/bpf/bpf_iter.c:158
vfs_read fs/read_write.c:572
ksys_read fs/read_write.c:716
do_syscall_64 arch/x86/entry/syscall_64.c:84
entry_SYSCALL_64_after_hwframe arch/x86/entry/entry_64.S:121
Kernel panic - not syncing: KASAN: panic_on_warn set ... |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_sync: Fix command skb lifetime during scan setup
During PA sync scan setup, hci_le_set_ext_scan_param_sync() gets the
address used for the PA_LINK lookup from hci_sent_cmd_data(). The
returned pointer borrows storage from sent_cmd or req_skb, without
holding a reference to either skb.
The scan worker runs on req_workqueue while hci_cmd_work() runs on the
separate device workqueue. After the scan worker loads sent_cmd, the
command worker can free and replace it before hci_sent_cmd_data()
dereferences the skb. The command payload can also be freed between
returning from the helper and comparing the address. The connection
lookup's RCU critical section does not protect the command skb.
KASAN reported:
BUG: KASAN: slab-use-after-free in hci_sent_cmd_data+0x27c/0x2f0
Workqueue: hci0 hci_cmd_sync_work
Call Trace:
hci_sent_cmd_data+0x27c/0x2f0
hci_le_set_scan_param_sync+0x43a/0x850
hci_passive_scan_sync+0xb09/0x1460
hci_update_passive_scan_sync+0x47c/0x6e0
hci_le_pa_create_sync+0x200/0xa70
hci_cmd_sync_work+0x13c/0x290
Allocated by task 95:
skb_clone+0x13f/0x340
hci_cmd_work+0x2a9/0x7e0
Freed by task 95:
kmem_cache_free+0xba/0x3a0
hci_cmd_work+0x29c/0x7e0
Use hdev->lock to serialize the address snapshot with sent_cmd
replacement. Protect req_skb replacement and completion cleanup with
the same lock because the helper falls back to that skb. Copy the
address before releasing the lock and use the copy for the existing
RCU-protected connection lookup. Release the mutex before sending or
waiting for commands, preserving the lookup and completion ordering. |
| In the Linux kernel, the following vulnerability has been resolved:
fsverity: RCU-delay the freeing of struct fsverity_info
__fsverity_get_info() calls rhashtable_lookup_fast(), which just uses
rcu_read_lock() and doesn't directly synchronize with
fsverity_remove_info().
For the same inode this isn't a problem: its fsverity_info is removed
only at inode eviction time or upon failure to enable verity, when the
inode no longer needs its fsverity_info and it will no longer be
accessed via that inode.
However, this is broken and can cause a use-after-free for concurrent
__fsverity_get_info() for *different* inodes. Those rely on following
fsverity_info::rhash_head in the rhashtable under rcu_read_lock() only.
They also use fsverity_info::inode to do the key comparison.
Fix this by RCU-delaying the freeing of 'struct fsverity_info' after
it's been removed from the rhashtable. |
| In the Linux kernel, the following vulnerability has been resolved:
audit: fix exe mark UAF in kill_rules()
kill_rules() removes mixed AUDIT_DIR and AUDIT_EXE rules when an audit
tree is pruned. It drops entry->rule.exe before removing the rule from
the RCU-visible filter lists.
After a rule has been installed with AUDIT_ADD_RULE, which requires
CAP_AUDIT_CONTROL, removing the watched directory can race with another
task that is still evaluating the rule. In that case, fsnotify can free
the executable mark before the reader reaches audit_mark_compare(),
causing a use-after-free.
KASAN reports:
BUG: KASAN: slab-use-after-free in audit_mark_compare+0x8d/0xa0
Unlink the published rules from the RCU-visible lists and retain them
on tree->rules for cleanup. If any rule has an executable mark, wait for
a single RCU grace period before removing the marks and scheduling the
entries for freeing. Otherwise, call_rcu() already provides the required
deferred freeing without a synchronous wait. |
| In the Linux kernel, the following vulnerability has been resolved:
KVM: x86: Re-pend GET_NESTED_STATE_PAGES if getting said pages fails
Re-pend GET_NESTED_STATE_PAGES before exiting to userspace if getting the
nested pages fails in the KVM_RUN path. If userspace re-runs the vCPU, and
vmcs02 holds valid PFNs from the *previous* run of L2, then KVM could
re-enter L2 with stale, unpinned PFNs mapped into e.g. the vAPIC page.
Note, both SVM and VMX (as of commit 11722439fb20 ("KVM: nVMX: Ensure
KVM_REQ_GET_NESTED_STATE_PAGES is cleared on VM-Exit") ensure the request
is cleared on VM-Exit (including the "forced" case), i.e. there is no risk
of double-mapping due to emulated VMLAUNCH/VMRESUME/VMRUN *and* the request
trying to map the nested pages. |
| In the Linux kernel, the following vulnerability has been resolved:
llc: fix skb UAF and leaks on llc_mac_hdr_init() failure
In llc_conn_ac_resend_i_xxx_x_set_0_or_send_rr(), if llc_mac_hdr_init()
fails, kfree_skb(skb) is called instead of kfree_skb(nskb). This leaks
the newly allocated nskb, reads from the freed skb via LLC_I_GET_NR(pdu),
and double-frees skb when llc_conn_state_process() drops its reference.
In llc_sap_action_send_xid_r() and llc_sap_action_send_test_r(), nskb is
leaked if llc_mac_hdr_init() returns an error.
Free nskb in all three error paths. |
| In the Linux kernel, the following vulnerability has been resolved:
sctp: discard the rest of the packet on a stale-cookie error
When an association is in COOKIE-ECHOED state and the peer sends a
bundled [ERROR(Stale Cookie)][DATA] packet from one of its non-primary
addresses, processing the ERROR chunk takes the non-fatal stale-cookie
retry path sctp_sf_do_5_2_6_stale(), which queues
SCTP_CMD_DEL_NON_PRIMARY while keeping the association alive.
sctp_cmd_del_non_primary() removes every non-primary transport -
including the very transport this packet arrived on, which is still
referenced by the receive lookup and shared by all chunks of the
packet via chunk->transport.
sctp_assoc_rm_peer() does redirect asoc->peer.last_data_from away from
the removed transport, but right afterwards the bundled DATA chunk
makes sctp_assoc_bh_rcv() re-register
asoc->peer.last_data_from = chunk->transport unconditionally, undoing
the redirection with the just-removed transport.
Once the packet is done, the receive reference is dropped and the
transport is RCU-freed, while the surviving association keeps the
dangling last_data_from. A later FWD-TSN (or the delayed SACK timer)
makes sctp_gen_sack() dereference it (->param_flags and friends), and
sctp_make_sack()/sctp_outq_select_transport() may write to the freed
object and link it into the live transport list. This is a
use-after-free triggerable by any malicious SCTP peer (or a local
unprivileged user acting as one) with no capabilities required:
BUG: KASAN: slab-use-after-free in sctp_do_sm+0x498a/0x5660
Read of size 4 at addr ffff88800e1e356c by task poc/115
Call Trace: sctp_do_sm <- sctp_assoc_bh_rcv <- sctp_inq_push <-
sctp_rcv <- ip_protocol_deliver_rcu <- ip_rcv
Allocated: sctp_transport_new <- sctp_assoc_add_peer <-
sctp_process_init (INIT-ACK processing)
Freed: kfree <- sctp_transport_destroy_rcu <- rcu_core
(call_rcu queued by sctp_transport_put at end of sctp_rcv)
The buggy address is located 364 bytes inside of freed 1024-byte
region [ffff88800e1e3400, ffff88800e1e3800), cache kmalloc-1k
Note that commit 03a9d10ecf71 ("sctp: drop a chunk if its transport
was removed") only covers the window between the receive lookup and
the chunk processing (e.g. an ASCONF DEL-IP racing the socket backlog);
here the transport is removed *while* the packet is being processed,
by an earlier chunk of the same packet, so the drop in sctp_inq_push()
does not reach this path. Verified with the bundled [ERROR(Stale
Cookie)][DATA] + FWD-TSN reproducer: the KASAN report above still
fires with that commit applied, and is gone with this patch on top.
Fix it by discarding the rest of the packet on this path, as suggested
by Xin. After the stale-cookie ERROR has sent the association back to
COOKIE-WAIT and removed the non-primary transports, the remaining
chunks of the packet can only run against the restarted handshake
while referencing the removed arrival transport through
chunk->transport: besides the last_data_from registration above,
sctp_cmd_setup_t2() and the sctp_make_*() reply builders would also
copy that pointer into association-lifetime state that
sctp_assoc_rm_peer() has already sanitized. Let the peer retransmit
them, in line with what sctp_inq_push() does for chunks whose
transport was removed before processing. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/amdkfd: fix use-after-free and multi-container gap in kfd_dev_mapping
kfd_dev_mapping caches the address_space of the first /dev/kfd opener
so that the GPU reset path can call unmap_mapping_range() to zap all
userspace mappings of doorbell and MMIO ranges. This design has two
bugs that both manifest under SRIOV with multiple containers:
1. Use-after-free / rwsem deadlock. The cached pointer refers to an
inode owned by the first opener's container. When that container
exits and its inode is released, kfd_dev_mapping becomes a dangling
pointer. A subsequent GPU reset dereferences it inside
unmap_mapping_range(), which takes i_mmap_rwsem on the freed inode,
causing a hard hang observable as an uninterruptible rwsem wait.
2. Multi-container gap. Only the first opener's address_space is cached;
VMAs created by later openers live in a different address_space and
are never reached by unmap_mapping_range(). After a GPU reset those
stale mappings keep doorbell and MMIO pages accessible to guest
userspace with no GPU behind them, risking PCIe transaction timeouts
and NMI panics.
Fix both bugs with the same approach used by DRM core (drm_drv.c):
create a private pseudo-filesystem at module init time and allocate one
anonymous inode from it. In kfd_open() redirect every opener's
file->f_mapping to that inode's address_space. The inode is
module-owned, lives exactly as long as the amdgpu module, and collects
VMAs from all openers in one address_space. A single
unmap_mapping_range() call in the reset path then correctly reaches
every container's mappings with no dangling pointer risk.
The hang manifests as an NMI backtrace on the GPU reset workqueue stuck
spinning in rwsem_down_read_slowpath() with a corrupted i_mmap_rwsem:
Workqueue: amdgpu-reset-dev xgpu_ai_mailbox_flr_work [amdgpu]
Call Trace:
<TASK>
kvm_wait+0x1f/0x40
__pv_queued_spin_lock_slowpath+0x31d/0x3a0
_raw_spin_lock_irq+0x51/0x80
rwsem_down_read_slowpath+0xb3/0x550
down_read+0x48/0xd0
unmap_mapping_range+0x71/0x140
kfd_dev_unmap_mapping_range+0x5b/0x140 [amdgpu]
amdgpu_amdkfd_clear_kfd_mapping+0xd8/0x190 [amdgpu]
amdgpu_device_gpu_recover+0x232/0x450 [amdgpu]
xgpu_ai_mailbox_flr_work+0xb5/0xc0 [amdgpu]
process_one_work+0x18e/0x3e0
worker_thread+0x2e3/0x420
kthread+0x10a/0x230
(cherry picked from commit 1128b4a52de1572e87431de837fd9850cb99542c) |
| In the Linux kernel, the following vulnerability has been resolved:
drm/nouveau: RCU-free the scheduler-containing nouveau_sched
struct nouveau_sched embeds a struct drm_gpu_scheduler (base).
nouveau_sched_destroy() calls nouveau_sched_fini() (which does
drm_sched_fini(&sched->base)) and then frees the object with plain
kfree(sched).
drm_sched_fence_get_timeline_name() returns fence->sched->name, and the
scheduler fence keeps a .release callback so it is not ops-detached on
signalling. A finished fence exported to userspace via drm_syncobj /
sync_file therefore keeps pointing at &sched->base after nouveau_sched_destroy(),
and a later get_timeline_name() -- reachable unprivileged through
SYNC_IOC_FILE_INFO -- dereferences freed memory (KASAN slab-use-after-free
read).
Per the dma-fence lifetime contract the exporter must keep the data backing a
signalled fence alive for an RCU grace period. Free the scheduler-containing
object with kfree_rcu() instead of kfree(). |
| In the Linux kernel, the following vulnerability has been resolved:
net: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry
In a case where skb with an unconfirmed ct entry gets cloned, we may
end up committing both but with different sets of extensions.
The series of events:
1. The first clone wants to commit and runs the helpers wiring up
the extension pointer into the expectation list.
2. Then it looses the confirmation keeping the entry unconfirmed.
3. Second clone now wants to commit labels and adds the new extension
for that breaking the pointer in the expectation list causing
UAF on the destruction path later.
While this is possible to trigger, there should be no practical
network pipeline where committing both clones without modifications
into the same zone is needed. So, let's just reset the entry in case
for some reason we got an skb with a shared one during commit. This
doesn't affect any known use cases, but avoids any potential problems
with sharing and modification of the unconfirmed ct entry.
The fixes tag points to the introduction of helpers, since that's the
main UAF trigger for the sharing. |
| In the Linux kernel, the following vulnerability has been resolved:
net: openvswitch: conntrack: fix helper UAF due to extensions realloc
While calling the helpers, a raw pointer to the extensions area is
wired into expectations list:
-> nf_ct_helper()
-> helper->help()
-> nf_ct_expect_related_report()
-> nf_ct_expect_insert()
-> hlist_add_head_rcu(&exp->lnode, &master_help->expectations)
In case the connection is not confirmed yet, more extensions can be
added afterwards with *_ext_add() calls reallocating the extension
space and leaving the now invalid pointer in the expectations list
that is later accessed while removing the expectation.
Make sure that helpers are called at the end after all the other
extensions are already added.
Note that the helper rejection now leaves the mark and labels set,
but that's not different from how the NAT was handled before or how
the mark and the labels were handled on confirmation failure. And
there are no atomicity guarantees provided by the API anyway. |
| In the Linux kernel, the following vulnerability has been resolved:
net: bridge: mdb: restart port group walk after deletion
br_mdb_flush_pgs() keeps a pointer-to-pointer cursor while walking
mp->ports. br_multicast_del_pg() can re-enter the same MDB entry through
br_multicast_sg_del_exclude_ports() and unlink other port groups. If the
cursor points into one of those groups, the next iteration dereferences a
stale cursor and can leave mp->ports pointing at freed memory.
A following RTM_GETMDB exposes the dangling pointer:
BUG: KASAN: slab-use-after-free in br_mdb_dump
Read of size 8
br_mdb_dump
rtnl_mdb_dump
rtnl_dumpit
netlink_dump
Reset the cursor to mp->ports after every deletion. The deletion removes at
least the selected group, so the restarted walk always makes progress. |
| In the Linux kernel, the following vulnerability has been resolved:
RISC-V: KVM: Synchronize hrtimer callback during teardown
The non-Sstc hrtimer callback clears next_set before its final uses of
the enclosing vCPU. If teardown observes next_set as false while the
callback is still running, kvm_riscv_vcpu_timer_cancel() skips
hrtimer_cancel() and kvm_destroy_vcpus() can free the vCPU before the
callback enters kvm_riscv_vcpu_set_interrupt().
A guest can arm the timer with SBI TIME and request shutdown with SBI
legacy shutdown or SRST. A VMM that honors KVM_EXIT_SYSTEM_EVENT and
destroys the VM supplies the teardown side of the race; no post-launch
host ioctl is needed to arm or request teardown.
On upstream master 62cc90241548, generic KASAN reported:
BUG: KASAN: slab-use-after-free in do_raw_spin_lock
Write of size 4 at addr ff60000005e58898
kvm_riscv_vcpu_set_interrupt
kvm_riscv_vcpu_hrtimer_expired
__hrtimer_run_queues
hrtimer_interrupt
The object was allocated by KVM_CREATE_VCPU and freed concurrently by:
kvm_destroy_vcpus
kvm_arch_destroy_vm
kvm_destroy_vm
__fput
For deterministic validation, I added mdelay(1000) immediately after
the existing next_set = false assignment. This only widens the
existing post-clear callback window. A no-delay trace build naturally
reached the callback-after-teardown-start/before-deinit ordering in 12
of 200 runs, but 1,500 stock-kernel stress iterations did not produce a
KASAN report, so natural reproduction is timing-sensitive.
Always invoke hrtimer_cancel() for an initialized timer. Preserve the
existing -EINVAL result when the timer is no longer set, but only after
synchronizing with a running callback.
With this patch, hrtimer_cancel() blocked for the full widened callback
window before vCPU destruction. KASAN reported no error in 100
fixed-and-widened runs or 200 fix-only timing-sweep runs. |
