| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
net/sched: fix use-after-free in __tcf_action_put()
__tcf_action_put() decrements the reference count before decrementing the
binding count. Another thread can free the action between these operations,
causing the binding-count update to access freed memory. KASAN reports it
as:
BUG: KASAN: slab-use-after-free in __tcf_action_put+0x327/0x340
Write of size 4 at addr ff11000000d46420 by task tc-put-pause/64
Hold the action IDR mutex across both counter updates and IDR removal,
keeping cleanup outside the lock. |
| In the Linux kernel, the following vulnerability has been resolved:
tcp: fix use-after-free in do_tcp_getsockopt(TCP_CONGESTION)
do_tcp_getsockopt() reads icsk->icsk_ca_ops->name without holding
rcu_read_lock(). Since commit 0baf26b0fcd7 ("bpf: tcp: Support
tcp_congestion_ops in bpf"), icsk_ca_ops can point to dynamically
allocated BPF struct_ops memory that may be freed concurrently via
setsockopt(TCP_CONGESTION), leading to a use-after-free.
BUG: KASAN: slab-use-after-free in _copy_to_user+0x37/0x60
Read of size 16 at addr ffff888013505260 by task exploit/149
_copy_to_user+0x37/0x60
do_tcp_getsockopt+0x158a/0x2460 (net/ipv4/tcp.c:4585)
tcp_getsockopt+0x91/0xf0
__sys_getsockopt+0xf7/0x170
Fix this by holding rcu_read_lock() around the ca_ops->name access,
using READ_ONCE() to load icsk_ca_ops, and copying the name to a
stack buffer before releasing the lock. Also annotate the relevant
icsk_ca_ops stores with WRITE_ONCE() to fix the accompanying KCSAN
data-race issue. |
| In the Linux kernel, the following vulnerability has been resolved:
tcp: fix use-after-free in do_tcp_getsockopt(TCP_CC_INFO)
do_tcp_getsockopt() reads icsk->icsk_ca_ops and dereferences the
get_info function pointer without rcu_read_lock(). With BPF struct_ops
congestion control, ca_ops can point to dynamically allocated memory
that is freed concurrently, resulting in a use-after-free when the
kernel dereferences or calls through the stale pointer.
BUG: KASAN: slab-use-after-free in do_tcp_getsockopt+0x2037/0x23e0
Read of size 8 at addr ffff888013701258 by task exploit/149
do_tcp_getsockopt+0x2037/0x23e0 (net/ipv4/tcp.c:4564)
tcp_getsockopt+0x91/0xf0
__sys_getsockopt+0xf7/0x170
Fix this by wrapping the ca_ops load and get_info call within
rcu_read_lock()/rcu_read_unlock(), and using READ_ONCE() to load
the icsk_ca_ops pointer. |
| In the Linux kernel, the following vulnerability has been resolved:
dm-integrity: fix infinite loop on discard with large tag size
When integrity_metadata handles a discard, it fills a buffer with
DISCARD_FILLER and writes it over the tags, max_blocks blocks at a
time. If the kmalloc fails, the buffer is the on-stack array
checksums_onstack and max_size is set to HASH_MAX_DIGESTSIZE. So if the
tag size is larger than HASH_MAX_DIGESTSIZE, max_blocks is zero, bi_size
is never decremented and the loop never terminates.
Fix this by using sizeof(checksums_onstack) as max_size. The array has
MAX_TAG_SIZE bytes since commit b93b6643e9b5 ("dm integrity: fix a
crash with unusually large tag size"), so max_blocks is at least 1. |
| In the Linux kernel, the following vulnerability has been resolved:
xfs: don't hold buffer locks across sync transaction commit in xfs_sync_sb_buf
xfs_sync_sb_buf() holds sb/rtsb buffer locks across a synchronous
xfs_trans_commit(), which flushes the CIL push workqueue internally.
If shutdown occurs during the CIL push, xfs_buf_item_unpin() needs to
lock these buffers to fail them, causing a deadlock:
setlabel: holds buf lock -> flush_workqueue(xfs-cil)
CIL push worker: xfs_buf_item_unpin -> xfs_buf_lock(same buf)
Remove the xfs_trans_bhold() calls so that commit releases the buffer
locks normally. After the sync commit, re-acquire the buffers via
mp->m_sb_bp / mp->m_rtsb_bp for the on-disk writeback. |
| In the Linux kernel, the following vulnerability has been resolved:
io_uring/cancel: don't spin on local work the task can't run
io_uring_cancel_generic() refuses to sleep while any ring on the exiting
task's tctx has local work pending. It assumes the task is that ring's
submitter and that the next io_uring_try_cancel_requests() pass will run
the work. This does not hold for a ring that was still
IORING_SETUP_R_DISABLED when the task got its tctx node from
io_uring_create() or io_ringfd_register(). The submitter is set later by
IORING_REGISTER_ENABLE_RINGS, possibly from another task, and only the
submitter may run local work on an IORING_SETUP_DEFER_TASKRUN ring. To
the exiting task the work stays pending forever, the loop never reaches
schedule(), and the task trips the WARN_ON_ONCE() once and then spins in
do_exit().
An unprivileged user can set this up at will by creating a disabled
ring, having a child enable it and stop, posting to the ring with
IORING_OP_MSG_RING and exiting with a request in flight that only the
child can complete. The exiting thread burns a CPU until the child runs
or dies, and with panic_on_warn set the WARN panics the kernel.
Fix by skipping the sleep only when io_allowed_defer_tw_run() allows the
task to run the work. This is reasonable since work it cannot run cannot
complete any of its requests either, so nothing is lost by sleeping.
Drop the WARN_ON_ONCE() since handing a disabled ring to another thread
is a supported scenario, not a bug state. |
| In the Linux kernel, the following vulnerability has been resolved:
sctp: validate chunk length in the inqueue parser
SCTP chunks always include a four-byte generic header, but
sctp_inq_pop() currently accepts shorter declared lengths. A zero-length
chunk leaves chunk_end at the current header.
When ASCONF is covered by the association's SCTP-AUTH policy,
sctp_assoc_bh_rcv() can continue before the state machine performs its
normal chunk-length check. sctp_inq_pop() then returns the same malformed
chunk repeatedly and the receive softirq can lock up.
A remote SCTP peer can trigger this after establishing an association on
a kernel built with CONFIG_IP_SCTP and configured with
net.sctp.addip_enable=1 and net.sctp.auth_enable=1. The reproducer did
not require application credentials, a shared SCTP AUTH key, or
net.sctp.addip_noauth_enable=1.
On commit f967455fb2a5 ("seg6: reset IP6CB after IPv6 decapsulation"),
one zero-length ASCONF caused repeated
watchdog soft-lockup reports in a two-vCPU KVM guest. All 3 pre-trigger
health probes succeeded, while 36 of 37 post-trigger probes failed. With
this change, all 37 post-trigger probes succeeded and no equivalent
soft-lockup signature appeared.
Reject chunks shorter than the generic SCTP header at the shared inqueue
parser boundary. Mark the packet for discard before either caller can
continue processing it, while preserving the four-byte generic minimum.
Declared-length 1 through 4 controls and kernel-generated ASCONF traffic
remained healthy. The patched sctp_hello selftest passed for IPv4 and
IPv6.
The complete private reproducer and validation evidence are available
directly to maintainers on request. |
| In the Linux kernel, the following vulnerability has been resolved:
sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ
With SCX_OPS_ENQ_LAST, the last runnable task on a CPU is passed to
ops.enqueue() instead of being kept running. Exiting tasks without
SCX_OPS_ENQ_EXITING, migration disabled tasks without
SCX_OPS_ENQ_MIGRATION_DISABLED and tasks on an offline rq skip ops.enqueue()
and go straight to the local DSQ. This happens in put_prev_task_scx() after
the pick has settled on idle, so nothing reschedules the CPU, which idles
with the task queued until an unrelated wakeup lands on it or the watchdog
fires.
scx_mitosis, which sets SCX_OPS_ENQ_LAST without SCX_OPS_ENQ_EXITING, hit
this during mass cgroup teardown: exiting tasks stuck in exit_mmap() for
over 40 seconds.
A task put on the local DSQ runs, as anywhere else. If the SCX_ENQ_LAST
enqueue left the task on this CPU's local DSQ, set need_resched on the task
being switched in, as proxy_resched_idle() does. resched_curr() would flag
the task being put instead, and __schedule() clears that right after the
pick. |
| In the Linux kernel, the following vulnerability has been resolved:
workqueue: Fix unbound pool lifetime for pending pwqs
KASAN reports a use-after-free of an unbound worker_pool in
node_activate_pending_pwq():
BUG: KASAN: slab-use-after-free in _raw_spin_trylock+0x6d/0x120
Read of size 4 at addr ffff8880089ce000 by task kworker/u22:0/318
CPU: 1 UID: 0 PID: 318 Comm: kworker/u22:0 Not tainted 7.2.0 #1 PREEMPT(lazy)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Workqueue: 0x0 (flush-8:0)
Call Trace:
<TASK>
dump_stack_lvl+0x53/0x70
print_report+0xce/0x610
kasan_report+0xce/0x100
_raw_spin_trylock+0x6d/0x120
pwq_dec_nr_in_flight+0x4b4/0xcb0
process_one_work+0x921/0x11a0
worker_thread+0x4d0/0xd20
kthread+0x2de/0x3c0
ret_from_fork+0x3aa/0x620
ret_from_fork_asm+0x1a/0x30
</TASK>
Allocated by task 311:
alloc_pwq+0x439/0xca0
apply_wqattrs_prepare+0x75e/0xd10
apply_workqueue_attrs_locked+0x44/0xa0
wq_nice_store+0x350/0x450
Freed by task 0:
kfree+0x127/0x3b0
rcu_core+0x523/0x1780
handle_softirqs+0x1b3/0x610
Last potentially related work creation:
put_unbound_pool+0x3f3/0x7d0
pwq_release_workfn+0x494/0x8e0
kthread_worker_fn+0x1ff/0x790
Canceling the last inactive work skips pwq_dec_nr_active(), so an empty
pwq can remain on pending_pwqs when its refcnt reaches zero.
pwq_release_workfn() currently puts the pool before removing that pwq.
If this drops the last pool reference, the pool can be RCU-freed while
the pwq remains reachable, and node_activate_pending_pwq() may trylock
the freed pool->lock.
Remove the pwq from pending_pwqs before putting the pool. |
| In the Linux kernel, the following vulnerability has been resolved:
wifi: brcmfmac: fix P2P device removal race in brcmf_detach()
When the driver is removed while the user space process that created
the P2P device (e.g. wpa_supplicant) is still exiting, the P2P device
interface is removed twice and the kernel crashes.
The two paths are:
- wpa_supplicant, on exit, sends NL80211_CMD_DEL_INTERFACE for the P2P
device. nl80211_del_interface() holds RTNL and the wiphy mutex and
calls brcmf_p2p_del_vif(), which disables discovery and waits up to
1.5 s for BRCMF_E_IF_DEL. Then it calls brcmf_remove_interface(),
which unregisters the wdev and frees the vif and the ifp.
- brcmf_detach() sets the bus down, so BRCMF_E_IF_DEL never arrives,
and calls brcmf_remove_interface(ifp, false) for the same ifp.
brcmf_p2p_ifp_removed() reads ifp->vif and then blocks on
rtnl_lock(). When brcmf_p2p_del_vif() releases RTNL, it calls
cfg80211_unregister_wdev() on the wdev that was already unregistered
and freed.
The second list_del_rcu() of wdev->list faults on LIST_POISON2:
brcmfmac: brcmf_p2p_del_vif delete P2P vif
brcmfmac: brcmf_p2p_deinit_discovery enter
brcmfmac: brcmf_p2p_del_vif P2P: GO_NEG_PHASE status cleared
brcmfmac: brcmf_detach Enter
brcmfmac: brcmf_bus_change_state 1 -> 0
brcmfmac: brcmf_remove_interface Enter, bsscfgidx=1, ifidx=0
brcmfmac: brcmf_del_if Enter, bsscfgidx=1, ifidx=0
brcmfmac: brcmf_p2p_ifp_removed P2P: device interface removed
[1.5 s later, brcmf_p2p_del_vif() timed out]
brcmfmac: brcmf_remove_interface Enter, bsscfgidx=1, ifidx=0
brcmfmac: brcmf_del_if Enter, bsscfgidx=1, ifidx=0
brcmfmac: brcmf_p2p_ifp_removed P2P: device interface removed
Unable to handle kernel paging request at virtual address dead000000000122
Internal error: Oops: 96000044 [#1] PREEMPT_RT SMP
pc : _cfg80211_unregister_wdev+0x6c/0x264 [cfg80211]
Call trace:
_cfg80211_unregister_wdev+0x6c/0x264 [cfg80211]
cfg80211_unregister_wdev+0x10/0x1c [cfg80211]
brcmf_p2p_ifp_removed+0x84/0xb0 [brcmfmac]
brcmf_remove_interface+0x1f4/0x254 [brcmfmac]
brcmf_detach+0x88/0x180 [brcmfmac]
brcmf_sdio_remove+0x90/0x7b0 [brcmfmac]
brcmf_sdiod_remove+0x20/0xa0 [brcmfmac]
brcmf_ops_sdio_remove+0xbc/0x12c [brcmfmac]
sdio_bus_remove+0x38/0x144
device_release_driver_internal+0x1e8/0x2c0
device_release_driver+0x14/0x20
brcmf_sdio_bus_remove+0x2c/0x40 [brcmfmac]
brcmf_fwvid_unregister_vendor+0xd8/0x170 [brcmfmac]
__exit_compat+0x18/0x418 [brcmfmac_cyw]
__arm64_sys_delete_module+0x1ac/0x244
The log was taken with debug=0x406 on an i.MX 8M Plus board with a
CYW55513 (Sona IF513) on SDIO. The driver is the Ezurio backport of
brcmfmac from v6.18.22 on a 5.4-rt kernel. The code involved is the same
in mainline.
To reproduce:
1. Start wpa_supplicant on wlan0 and let it associate. It creates the
P2P device (iw dev shows "type P2P-device").
2. Stop wpa_supplicant and remove the driver without waiting for
wpa_supplicant to exit:
kill $(pidof wpa_supplicant)
rmmod brcmfmac_cyw brcmfmac
The crash is reproducible on that board.
For the interface without a netdev (the P2P device), take RTNL and the
wiphy mutex in brcmf_detach() before reading iflist, and remove it with
locked=true. If brcmf_p2p_del_vif() runs first, brcmf_detach() finds the
slot empty. If brcmf_detach() runs first, nl80211 does not find the wdev
any more. The interfaces with a netdev are removed as before, because
brcmf_del_if() takes RTNL on its own for the primary interface. |
| In the Linux kernel, the following vulnerability has been resolved:
tipc: hold a reference to nodes found by link name
tipc_node_find_by_name() returns a node after dropping its RCU read lock
without taking a reference. The LINK_SET, LINK_GET and LINK_RESET_STATS
handlers then lock and access the node, racing with timer-driven cleanup of
a down peer. Generic netlink serialization does not exclude the node
timer.
The following interleaving can leave a handler using a freed node:
CPU 0: find the node under RCU and release the node read lock
CPU 1: tipc_node_timeout() clears the links and unlinks the down node
CPU 1: drop the list and timer references, queuing tipc_node_free()
CPU 0: leave the RCU read-side critical section
CPU 1: complete the grace period and free the node
CPU 0: acquire the node lock through the stale pointer
LINK_SET also uses the node's media address after releasing the node lock,
when passing queued packets to tipc_bearer_xmit().
KASAN on v7.3-rc5 reported:
BUG: KASAN: slab-use-after-free in _raw_read_lock_bh
Write of size 4 at addr ffff88807e06f008 by task poc/92
Call Trace:
_raw_read_lock_bh kernel/locking/spinlock.c:287
tipc_nl_node_set_link net/tipc/node.c:2475
genl_family_rcv_msg_doit net/netlink/genetlink.c:1114
genl_rcv_msg net/netlink/genetlink.c:1209
netlink_rcv_skb net/netlink/af_netlink.c:2575
Allocated by task 0:
tipc_node_create net/tipc/node.c:539
tipc_node_check_dest net/tipc/node.c:1196
tipc_disc_rcv net/tipc/discover.c:252
Freed by task 92:
kfree mm/slub.c:6801
rcu_core kernel/rcu/tree.c:2919
Last potentially related work creation:
__call_rcu_common.constprop.0 kernel/rcu/tree.c:3181
tipc_node_timeout net/tipc/node.c:814
Acquire a reference to the selected node with kref_get_unless_zero() before
leaving RCU, returning NULL if the node has already been released. Release
that reference on every caller exit after the last node access, including
transmission in LINK_SET. Keep the existing link lookup order and locking
so concurrent link removal still takes the existing error paths. |
| In the Linux kernel, the following vulnerability has been resolved:
ice: fix metadata_dst refcount handling on representor teardown
ice_eswitch_release_repr() uses metadata_dst_free() to release the
representor's metadata_dst. metadata_dst_free() directly frees the
underlying memory without checking the dst_entry refcount.
When ice_eswitch_port_start_xmit() processes a packet, it takes a
reference via dst_hold() and attaches the metadata_dst to the skb.
If the representor is torn down while packets are still queued on
the lower device (e.g. in a qdisc), the metadata_dst is freed while
references are still held.
Use dst_release() instead, which correctly decrements the refcount
and only frees the object when all references are dropped. The dst
subsystem already handles metadata_dst cleanup in dst_destroy() when
DST_METADATA is set.
Other drivers sharing this pattern (nfp, airoha, bnxt) already use
dst_release() for their metadata_dst lifecycle. |
| In the Linux kernel, the following vulnerability has been resolved:
memstick: core: wait for request completion before freeing card
In memstick_alloc_card() and memstick_set_rw_addr(),
wait_for_completion_timeout() is used to wait for device identification
and address configuration requests to complete.
The memstick subsystem does not provide an abort or cancellation
callback in struct memstick_host for in-flight requests. If
wait_for_completion_timeout() expires (for instance, when a USB transfer
or command retry is delayed), memstick_alloc_card() returns an error and
frees the memstick_dev structure via kfree(card).
However, the host controller driver (such as rtsx_usb_ms) is still
running the request asynchronously in worker context. When the transfer
eventually finishes, the driver writes into host->req->data, which
points to memory inside the already freed card structure. This leads to
a KASAN slab-use-after-free write:
BUG: KASAN: slab-use-after-free in ms_read_bytes+0x8fe/0x990
Write of size 1 at addr ffff88813c188079 by task kworker/1:5/5239
Workqueue: events rtsx_usb_ms_handle_req
Call Trace:
ms_read_bytes+0x8fe/0x990 drivers/memstick/host/rtsx_usb_ms.c:450
rtsx_usb_ms_issue_cmd drivers/memstick/host/rtsx_usb_ms.c:477 [inline]
rtsx_usb_ms_handle_req+0x557/0x1a00 drivers/memstick/host/rtsx_usb_ms.c:531
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
worker_thread+0x5ef/0xe50 kernel/workqueue.c:3560
kthread+0x373/0x450 kernel/kthread.c:436
Allocated by task 1662:
memstick_alloc_card drivers/memstick/core/memstick.c:383 [inline]
memstick_check+0x2c1/0x10d0 drivers/memstick/core/memstick.c:452
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
Freed by task 1662:
kfree+0x20c/0x650 mm/slub.c:6792
memstick_alloc_card drivers/memstick/core/memstick.c:420 [inline]
memstick_check+0x72b/0x10d0 drivers/memstick/core/memstick.c:452
process_one_work+0xac7/0x1b10 kernel/workqueue.c:3396
Host controller drivers (rtsx_usb_ms, jmb38x_ms, tifm_ms, r592) already
implement their own hardware and bus timeouts, and callers in
mspro_block and ms_block already rely on wait_for_completion()
unconditionally.
Replace wait_for_completion_timeout() with wait_for_completion() in
memstick_set_rw_addr() and memstick_alloc_card() so that the card
structure is never freed while an asynchronous request is in flight. |
| In the Linux kernel, the following vulnerability has been resolved:
dm: fix reading free memory in do_resume
When do_resume calls dm_table_get_mode(new_map), the call is done without
holding any locks (it only holds a reference to the md). It may be
possible that another concurrent ioctl on the same device will swap table
after dm_swap_table and before dm_table_get_mode. In this case,
dm_table_get_mode(new_map) reads freed memory.
This race condition was triggered by syzbot.
This commit fixes the race by reading mode of the new table before
dm_swap_table. Note that new_map is also passed to dm_ima_need_measure,
but this function doesn't attempt to dereference it, so this call should
be safe.
Note that this is not a security bug because only root can trigger it and
the commonly used tools such as lvm or cryptsetup do not call the ioctls
concurrently, so that they can't trigger it acceidentally. |
| In the Linux kernel, the following vulnerability has been resolved:
mmc: mtk-sd: Cancel request timeout work on remove
The driver queues req_timeout while a request is active.
msdc_request_done() uses cancel_delayed_work(), which does not wait for
a timeout callback that has already started.
The timeout callback calls mmc_request_done(), which wakes the request
waiter, and then continues to use host->dev_comp and check the SDIO IRQ.
During unbind, msdc_drv_remove() can return and the managed mmc_host can
be freed before the callback finishes.
KASAN reported use-after-free accesses in msdc_request_done() and
msdc_recheck_sdio_irq() in each of three unbind tests. The same tests
completed without a kernel diagnostic after this change.
Call cancel_delayed_work_sync() after mmc_remove_host() has stopped new
requests and before the driver releases the host resources. |
| In the Linux kernel, the following vulnerability has been resolved:
net/smc: protect clcsock lifetime in smc_getname
smc_getname() dereferences smc->clcsock without holding
clcsock_release_lock. Link-group termination can release the CLC socket
through smc_close_active_abort() while the SMC socket is still open,
for example after shutdown(SHUT_WR).
A getsockname() caller can load smc->clcsock, then the termination worker
can clear the pointer and call sock_release() before the caller accesses
clcsock->ops or invokes getname(). This causes a use-after-free; if the
worker clears the pointer before the load, it causes a NULL dereference.
The syscall's file reference keeps the SMC socket alive but does not
prevent asynchronous release of its CLC socket.
KASAN reported the following with test-only timing instrumentation:
BUG: KASAN: slab-use-after-free in smc_getname+0x19e/0x1b0
Read of size 8 at addr ffff888109abb4e0 by task poc/103
Call Trace:
smc_getname+0x19e/0x1b0
do_getsockname+0xe5/0x170
__sys_getsockname+0x8c/0x100
Allocated by task 95:
sock_alloc_inode+0x1e/0x280
sock_alloc+0x3d/0x240
__sock_create+0x7e/0x430
smc_create+0x121/0x240
Freed by task 0:
kmem_cache_free+0xcc/0x340
rcu_core+0x50a/0x1850
Last potentially related work creation:
evict+0x446/0x6c0
smc_clcsock_release+0xa8/0xd0
smc_close_active_abort+0x26a/0x3a0
__smc_lgr_terminate.part.0+0x137/0x2e0
Hold clcsock_release_lock across the pointer check and the getname()
callback to serialize with smc_clcsock_release(). Return -EBADF if the
CLC socket has already been released, preserving the existing peer
state check and the callback's return value otherwise. |
| In the Linux kernel, the following vulnerability has been resolved:
net: team: stop reusing skb after queue override
A nonzero dev_queue_xmit() result does not return ownership of the skb.
When an override port's qdisc drops it, the queue override helper used to
try another port or the mode transmit op with the freed skb.
Return the handoff decision separately from transmit success. Select only
the first override port under RCU and stop after handing it the skb,
regardless of the lower transmit result. Keep the existing success and
drop accounting.
BUG: KASAN: slab-use-after-free in sk_skb_reason_drop
Write of size 4 by task poc/5040
sk_skb_reason_drop (net/core/skbuff.c:1240)
dev_kfree_skb_any_reason (net/core/dev.c:3470)
ab_transmit (drivers/net/team/team_mode_activebackup.c:49)
team_xmit (drivers/net/team/team_core.c:1849)
__dev_direct_xmit (net/core/dev.c:4934)
Freed by task 5040:
__tcf_kfree_skb_list (net/sched/sch_generic.c:43)
__dev_queue_xmit (net/core/dev.c:4831)
team_xmit (drivers/net/team/team_core.c:1846)
Kernel panic - not syncing: KASAN: panic_on_warn set ... |
| In the Linux kernel, the following vulnerability has been resolved:
openvswitch: fix soft lockup in the netlink flow dump
A production compute node carrying a few thousand datapath flows hit a
soft lockup inside a single netlink flow dump and panicked.
ovs_flow_cmd_dump() calls ovs_flow_stats_get() for every flow it
emits, and that releases stats->lock with spin_unlock_bh() once per
CPU that has touched the flow. Every release is a local_bh_enable(),
and each one runs the pending softirq backlog in the dumping thread's
own context.
The skb bounds the flows one callback emits, but not the softirq work
it absorbs. On a CPU that carries the box's packet load the backlog
refills as fast as it drains, so the dumping thread becomes that CPU's
softirq engine. It never sleeps and it has no reschedule point, so
under voluntary preemption nothing can take the CPU away from it:
neither the ksoftirqd the kernel woke to take the work over, nor the
stopper thread the softlockup detector dispatches to refresh its
timestamp.
Hold BH off across the whole callback instead, the way
ctnetlink_dump_table() does, so the nested spin_unlock_bh() stop
draining softirqs. The loop already runs under rcu_read_lock() and
cannot sleep. What it gives up is preemption under CONFIG_PREEMPT,
since a BH-off region is not preemptible outside PREEMPT_RT. The
region stays short: the skb caps the flows one callback emits, and
empty buckets cost no skb space but are each visited once per dump, as
the cursor only moves forward. The table grows on insert and shrinks
only on flush, so the walk is bounded by the largest flow count the
datapath has held. The softirq backlog the callback used to absorb has
no bound at all. |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: RFCOMM: connect the session socket without rfcomm_mutex
An RFCOMM connect() issued while a BR/EDR link is being authenticated
makes lockdep report a circular dependency, and the reported cycle is a
real AB/BA between rfcomm_mutex and hdev->lock.
rfcomm_security_cfm() is called from the HCI event path, which already
holds hdev->lock:
hci_rx_work()
hci_event_packet()
hci_cc_read_enc_key_size() [hdev->lock]
hci_encrypt_cfm() [hci_cb_list_lock]
rfcomm_security_cfm() [rfcomm_mutex]
while an RFCOMM connect() from userspace takes the same two locks the
other way round:
rfcomm_sock_connect()
rfcomm_dlc_open() [rfcomm_mutex]
__rfcomm_dlc_open()
rfcomm_session_create()
kernel_connect()
l2cap_sock_connect()
l2cap_chan_connect() [hdev->lock]
WARNING: possible circular locking dependency detected
kworker/u131:1/1128 is trying to acquire lock:
rfcomm_mutex, at: rfcomm_security_cfm+0x31/0x3e0 [rfcomm]
but task is already holding lock:
hci_cb_list_lock, at: hci_cc_read_enc_key_size+0x1d2/0xcc0
Chain exists of:
rfcomm_mutex --> &hdev->lock --> hci_cb_list_lock
hci_auth_complete_evt() and hci_encrypt_change_evt() reach the callback
the same way.
Both orders have to be seen in the same boot, which is why a BR/EDR
connection alone is not enough to show it: a session set up by the
remote side is created by rfcomm_accept_connection() in krfcommd, which
calls kernel_accept() and never takes hdev->lock under rfcomm_mutex.
Connecting a device that authenticates and encrypts the link and then
calling connect() on an RFCOMM socket towards any address - the connect
does not have to succeed, the order is recorded before the page timeout
- reports it every time.
Only the session socket has to be connected with the lock held, and it
does not: nothing else can see the socket before it is put on the
session list. So connect it first and take rfcomm_mutex afterwards,
which removes the rfcomm_mutex -> hdev->lock order for good, rather
than keeping the HCI event path out of rfcomm_mutex.
rfcomm_session_create() becomes rfcomm_session_connect(), which returns
the connected socket without touching the session list, and
rfcomm_dlc_open() adds the session once it holds the lock again. If
another opener added a session for the same pair while this socket was
connecting, that session is used and this socket is dropped.
__rfcomm_dlc_open() now takes the session it should use, and its state
check runs after the lock is re-acquired, so a DLC that was opened or
closed in the meantime is still handled.
Over an existing ACL link the connection can complete before the
session reaches the list, and the wakeup from the socket callback is
then lost, so krfcommd is woken once the session is visible.
Connecting without the lock opens a window in which the socket can be
closed. The DLC is not on a session yet, so rfcomm_dlc_close() finds
nothing to do and returns without touching it, and rfcomm_dlc_open()
would then attach a DLC whose owner is gone. rfcomm_dlc_close() now
marks such a DLC with RFCOMM_CLOSED, and rfcomm_dlc_open() checks the
mark once it holds rfcomm_mutex again and drops the socket instead of
attaching the DLC. The mark is cleared when an open starts, so a DLC
that is reused is not affected. This covers both callers of
rfcomm_dlc_open(), the socket and the tty layer. |
| In the Linux kernel, the following vulnerability has been resolved:
namespace: don't inherit MNT_UMOUNT in clone_mnt()
MNT_UMOUNT gets raised on a mount that umount_tree() or umount_one() has
taken out of its namespace. It's never cleared. __detach_mounts()
unhooks a mount that carries it instead of unmounting it.
disconnect_mount() lets an unmounted child stay attached only if its
parent carries it. propagate_umount() takes it as the sign that a mount
is going to be unmounted when it decides what else can be unmounted,
where a chain of locked mounts ends and where a for reparenting an
overmount.
clone_mnt() copies the flags of the source and only masks
MNT_INTERNAL_FLAGS which doesn't include MNT_UMOUNT. A mount that was
lazily unmounted but is kept alive by a file descriptor can still be
copied when its root is an nsfs or pidfs file because may_copy_tree()
accepts those before checking whether the source is mounted at all:
mount --bind /proc/self/ns/net /tmp/x
exec 3< /tmp/x
umount -l /tmp/x
mount --bind /proc/self/fd/3 /tmp/y
The mount on /tmp/y is attached to the caller's namespace with
MNT_UMOUNT already set and every copy of it inherits the flag again.
That causes a number of bugs:
- Unlink its mountpoint from a mount namespace where it isn't one.
__detach_mounts() takes it for a mount that was unmounted earlier,
unhooks it from its parent and drops the reference the namespace
holds on it. It stays in the namespace with one reference too few
and as its own parent, so it can't be unmounted through the file
descriptor anymore and the namespace never finds it again. When the
namespace goes away it's leaked and points to a freed struct
mnt_namespace that may_change_propagation() and anon_ns_root() read
on the next propagation change or mount_setattr() through the file
descriptor.
- Make it shared and unmount a peer. trace_transfers() follows the
flag from the peer into it and strips it from its peer group.
- Let a propagated umount reach it. gather_candidates() marks it with
T_UMOUNT_CANDIDATE but never puts it on the candidate list, so the
mark is never cleared and every later propagated umount skips it. If
it's the parent of a locked mount handle_locked() takes it as the
cutoff and commits the locked child that should have stayed and
disconnect_mount() leaves that child attached to it, unmounted under
a mounted parent, which is what disconnect_mount() exists to
prevent. When the namespace goes away umount_tree() visits the child
a second time. And once __detach_mounts() has made it its own parent
reparent() never finds the end of the chain of unmounted parents.
A clone is a new mount that has never been unmounted. Add MNT_UMOUNT
to MNT_INTERNAL_FLAGS so clone_mnt() never copies it. And warn when
umount_tree() reaches a mount that already has it set. |
