| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
mm: swap: fix race between free_swap_and_cache() and swapoff()
There was previously a theoretical window where swapoff() could run and
teardown a swap_info_struct while a call to free_swap_and_cache() was
running in another thread. This could cause, amongst other bad
possibilities, swap_page_trans_huge_swapped() (called by
free_swap_and_cache()) to access the freed memory for swap_map.
This is a theoretical problem and I haven't been able to provoke it from a
test case. But there has been agreement based on code review that this is
possible (see link below).
Fix it by using get_swap_device()/put_swap_device(), which will stall
swapoff(). There was an extra check in _swap_info_get() to confirm that
the swap entry was not free. This isn't present in get_swap_device()
because it doesn't make sense in general due to the race between getting
the reference and swapoff. So I've added an equivalent check directly in
free_swap_and_cache().
Details of how to provoke one possible issue (thanks to David Hildenbrand
for deriving this):
--8<-----
__swap_entry_free() might be the last user and result in
"count == SWAP_HAS_CACHE".
swapoff->try_to_unuse() will stop as soon as soon as si->inuse_pages==0.
So the question is: could someone reclaim the folio and turn
si->inuse_pages==0, before we completed swap_page_trans_huge_swapped().
Imagine the following: 2 MiB folio in the swapcache. Only 2 subpages are
still references by swap entries.
Process 1 still references subpage 0 via swap entry.
Process 2 still references subpage 1 via swap entry.
Process 1 quits. Calls free_swap_and_cache().
-> count == SWAP_HAS_CACHE
[then, preempted in the hypervisor etc.]
Process 2 quits. Calls free_swap_and_cache().
-> count == SWAP_HAS_CACHE
Process 2 goes ahead, passes swap_page_trans_huge_swapped(), and calls
__try_to_reclaim_swap().
__try_to_reclaim_swap()->folio_free_swap()->delete_from_swap_cache()->
put_swap_folio()->free_swap_slot()->swapcache_free_entries()->
swap_entry_free()->swap_range_free()->
...
WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries);
What stops swapoff to succeed after process 2 reclaimed the swap cache
but before process1 finished its call to swap_page_trans_huge_swapped()?
--8<----- |
| In the Linux kernel, the following vulnerability has been resolved:
net: phy: qcom: at803x: fix kernel panic with at8031_probe
On reworking and splitting the at803x driver, in splitting function of
at803x PHYs it was added a NULL dereference bug where priv is referenced
before it's actually allocated and then is tried to write to for the
is_1000basex and is_fiber variables in the case of at8031, writing on
the wrong address.
Fix this by correctly setting priv local variable only after
at803x_probe is called and actually allocates priv in the phydev struct. |
| In the Linux kernel, the following vulnerability has been resolved:
af_unix: Fix garbage collector racing against connect()
Garbage collector does not take into account the risk of embryo getting
enqueued during the garbage collection. If such embryo has a peer that
carries SCM_RIGHTS, two consecutive passes of scan_children() may see a
different set of children. Leading to an incorrectly elevated inflight
count, and then a dangling pointer within the gc_inflight_list.
sockets are AF_UNIX/SOCK_STREAM
S is an unconnected socket
L is a listening in-flight socket bound to addr, not in fdtable
V's fd will be passed via sendmsg(), gets inflight count bumped
connect(S, addr) sendmsg(S, [V]); close(V) __unix_gc()
---------------- ------------------------- -----------
NS = unix_create1()
skb1 = sock_wmalloc(NS)
L = unix_find_other(addr)
unix_state_lock(L)
unix_peer(S) = NS
// V count=1 inflight=0
NS = unix_peer(S)
skb2 = sock_alloc()
skb_queue_tail(NS, skb2[V])
// V became in-flight
// V count=2 inflight=1
close(V)
// V count=1 inflight=1
// GC candidate condition met
for u in gc_inflight_list:
if (total_refs == inflight_refs)
add u to gc_candidates
// gc_candidates={L, V}
for u in gc_candidates:
scan_children(u, dec_inflight)
// embryo (skb1) was not
// reachable from L yet, so V's
// inflight remains unchanged
__skb_queue_tail(L, skb1)
unix_state_unlock(L)
for u in gc_candidates:
if (u.inflight)
scan_children(u, inc_inflight_move_tail)
// V count=1 inflight=2 (!)
If there is a GC-candidate listening socket, lock/unlock its state. This
makes GC wait until the end of any ongoing connect() to that socket. After
flipping the lock, a possibly SCM-laden embryo is already enqueued. And if
there is another embryo coming, it can not possibly carry SCM_RIGHTS. At
this point, unix_inflight() can not happen because unix_gc_lock is already
taken. Inflight graph remains unaffected. |
| In the Linux kernel, the following vulnerability has been resolved:
quota: Fix potential NULL pointer dereference
Below race may cause NULL pointer dereference
P1 P2
dquot_free_inode quota_off
drop_dquot_ref
remove_dquot_ref
dquots = i_dquot(inode)
dquots = i_dquot(inode)
srcu_read_lock
dquots[cnt]) != NULL (1)
dquots[type] = NULL (2)
spin_lock(&dquots[cnt]->dq_dqb_lock) (3)
....
If dquot_free_inode(or other routines) checks inode's quota pointers (1)
before quota_off sets it to NULL(2) and use it (3) after that, NULL pointer
dereference will be triggered.
So let's fix it by using a temporary pointer to avoid this issue. |
| In the Linux kernel, the following vulnerability has been resolved:
packet: annotate data-races around ignore_outgoing
ignore_outgoing is read locklessly from dev_queue_xmit_nit()
and packet_getsockopt()
Add appropriate READ_ONCE()/WRITE_ONCE() annotations.
syzbot reported:
BUG: KCSAN: data-race in dev_queue_xmit_nit / packet_setsockopt
write to 0xffff888107804542 of 1 bytes by task 22618 on cpu 0:
packet_setsockopt+0xd83/0xfd0 net/packet/af_packet.c:4003
do_sock_setsockopt net/socket.c:2311 [inline]
__sys_setsockopt+0x1d8/0x250 net/socket.c:2334
__do_sys_setsockopt net/socket.c:2343 [inline]
__se_sys_setsockopt net/socket.c:2340 [inline]
__x64_sys_setsockopt+0x66/0x80 net/socket.c:2340
do_syscall_64+0xd3/0x1d0
entry_SYSCALL_64_after_hwframe+0x6d/0x75
read to 0xffff888107804542 of 1 bytes by task 27 on cpu 1:
dev_queue_xmit_nit+0x82/0x620 net/core/dev.c:2248
xmit_one net/core/dev.c:3527 [inline]
dev_hard_start_xmit+0xcc/0x3f0 net/core/dev.c:3547
__dev_queue_xmit+0xf24/0x1dd0 net/core/dev.c:4335
dev_queue_xmit include/linux/netdevice.h:3091 [inline]
batadv_send_skb_packet+0x264/0x300 net/batman-adv/send.c:108
batadv_send_broadcast_skb+0x24/0x30 net/batman-adv/send.c:127
batadv_iv_ogm_send_to_if net/batman-adv/bat_iv_ogm.c:392 [inline]
batadv_iv_ogm_emit net/batman-adv/bat_iv_ogm.c:420 [inline]
batadv_iv_send_outstanding_bat_ogm_packet+0x3f0/0x4b0 net/batman-adv/bat_iv_ogm.c:1700
process_one_work kernel/workqueue.c:3254 [inline]
process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335
worker_thread+0x526/0x730 kernel/workqueue.c:3416
kthread+0x1d1/0x210 kernel/kthread.c:388
ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
value changed: 0x00 -> 0x01
Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 27 Comm: kworker/u8:1 Tainted: G W 6.8.0-syzkaller-08073-g480e035fc4c7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
Workqueue: bat_events batadv_iv_send_outstanding_bat_ogm_packet |
| In the Linux kernel, the following vulnerability has been resolved:
net/bnx2x: Prevent access to a freed page in page_pool
Fix race condition leading to system crash during EEH error handling
During EEH error recovery, the bnx2x driver's transmit timeout logic
could cause a race condition when handling reset tasks. The
bnx2x_tx_timeout() schedules reset tasks via bnx2x_sp_rtnl_task(),
which ultimately leads to bnx2x_nic_unload(). In bnx2x_nic_unload()
SGEs are freed using bnx2x_free_rx_sge_range(). However, this could
overlap with the EEH driver's attempt to reset the device using
bnx2x_io_slot_reset(), which also tries to free SGEs. This race
condition can result in system crashes due to accessing freed memory
locations in bnx2x_free_rx_sge()
799 static inline void bnx2x_free_rx_sge(struct bnx2x *bp,
800 struct bnx2x_fastpath *fp, u16 index)
801 {
802 struct sw_rx_page *sw_buf = &fp->rx_page_ring[index];
803 struct page *page = sw_buf->page;
....
where sw_buf was set to NULL after the call to dma_unmap_page()
by the preceding thread.
EEH: Beginning: 'slot_reset'
PCI 0011:01:00.0#10000: EEH: Invoking bnx2x->slot_reset()
bnx2x: [bnx2x_io_slot_reset:14228(eth1)]IO slot reset initializing...
bnx2x 0011:01:00.0: enabling device (0140 -> 0142)
bnx2x: [bnx2x_io_slot_reset:14244(eth1)]IO slot reset --> driver unload
Kernel attempted to read user page (0) - exploit attempt? (uid: 0)
BUG: Kernel NULL pointer dereference on read at 0x00000000
Faulting instruction address: 0xc0080000025065fc
Oops: Kernel access of bad area, sig: 11 [#1]
.....
Call Trace:
[c000000003c67a20] [c00800000250658c] bnx2x_io_slot_reset+0x204/0x610 [bnx2x] (unreliable)
[c000000003c67af0] [c0000000000518a8] eeh_report_reset+0xb8/0xf0
[c000000003c67b60] [c000000000052130] eeh_pe_report+0x180/0x550
[c000000003c67c70] [c00000000005318c] eeh_handle_normal_event+0x84c/0xa60
[c000000003c67d50] [c000000000053a84] eeh_event_handler+0xf4/0x170
[c000000003c67da0] [c000000000194c58] kthread+0x1c8/0x1d0
[c000000003c67e10] [c00000000000cf64] ret_from_kernel_thread+0x5c/0x64
To solve this issue, we need to verify page pool allocations before
freeing. |
| In the Linux kernel, the following vulnerability has been resolved:
nvme-fc: do not wait in vain when unloading module
The module exit path has race between deleting all controllers and
freeing 'left over IDs'. To prevent double free a synchronization
between nvme_delete_ctrl and ida_destroy has been added by the initial
commit.
There is some logic around trying to prevent from hanging forever in
wait_for_completion, though it does not handling all cases. E.g.
blktests is able to reproduce the situation where the module unload
hangs forever.
If we completely rely on the cleanup code executed from the
nvme_delete_ctrl path, all IDs will be freed eventually. This makes
calling ida_destroy unnecessary. We only have to ensure that all
nvme_delete_ctrl code has been executed before we leave
nvme_fc_exit_module. This is done by flushing the nvme_delete_wq
workqueue.
While at it, remove the unused nvme_fc_wq workqueue too. |
| In the Linux kernel, the following vulnerability has been resolved:
RDMA/irdma: Fix KASAN issue with tasklet
KASAN testing revealed the following issue assocated with freeing an IRQ.
[50006.466686] Call Trace:
[50006.466691] <IRQ>
[50006.489538] dump_stack+0x5c/0x80
[50006.493475] print_address_description.constprop.6+0x1a/0x150
[50006.499872] ? irdma_sc_process_ceq+0x483/0x790 [irdma]
[50006.505742] ? irdma_sc_process_ceq+0x483/0x790 [irdma]
[50006.511644] kasan_report.cold.11+0x7f/0x118
[50006.516572] ? irdma_sc_process_ceq+0x483/0x790 [irdma]
[50006.522473] irdma_sc_process_ceq+0x483/0x790 [irdma]
[50006.528232] irdma_process_ceq+0xb2/0x400 [irdma]
[50006.533601] ? irdma_hw_flush_wqes_callback+0x370/0x370 [irdma]
[50006.540298] irdma_ceq_dpc+0x44/0x100 [irdma]
[50006.545306] tasklet_action_common.isra.14+0x148/0x2c0
[50006.551096] __do_softirq+0x1d0/0xaf8
[50006.555396] irq_exit_rcu+0x219/0x260
[50006.559670] irq_exit+0xa/0x20
[50006.563320] smp_apic_timer_interrupt+0x1bf/0x690
[50006.568645] apic_timer_interrupt+0xf/0x20
[50006.573341] </IRQ>
The issue is that a tasklet could be pending on another core racing
the delete of the irq.
Fix by insuring any scheduled tasklet is killed after deleting the
irq. |
| In the Linux kernel, the following vulnerability has been resolved:
net: bridge: switchdev: Skip MDB replays of deferred events on offload
Before this change, generation of the list of MDB events to replay
would race against the creation of new group memberships, either from
the IGMP/MLD snooping logic or from user configuration.
While new memberships are immediately visible to walkers of
br->mdb_list, the notification of their existence to switchdev event
subscribers is deferred until a later point in time. So if a replay
list was generated during a time that overlapped with such a window,
it would also contain a replay of the not-yet-delivered event.
The driver would thus receive two copies of what the bridge internally
considered to be one single event. On destruction of the bridge, only
a single membership deletion event was therefore sent. As a
consequence of this, drivers which reference count memberships (at
least DSA), would be left with orphan groups in their hardware
database when the bridge was destroyed.
This is only an issue when replaying additions. While deletion events
may still be pending on the deferred queue, they will already have
been removed from br->mdb_list, so no duplicates can be generated in
that scenario.
To a user this meant that old group memberships, from a bridge in
which a port was previously attached, could be reanimated (in
hardware) when the port joined a new bridge, without the new bridge's
knowledge.
For example, on an mv88e6xxx system, create a snooping bridge and
immediately add a port to it:
root@infix-06-0b-00:~$ ip link add dev br0 up type bridge mcast_snooping 1 && \
> ip link set dev x3 up master br0
And then destroy the bridge:
root@infix-06-0b-00:~$ ip link del dev br0
root@infix-06-0b-00:~$ mvls atu
ADDRESS FID STATE Q F 0 1 2 3 4 5 6 7 8 9 a
DEV:0 Marvell 88E6393X
33:33:00:00:00:6a 1 static - - 0 . . . . . . . . . .
33:33:ff:87:e4:3f 1 static - - 0 . . . . . . . . . .
ff:ff:ff:ff:ff:ff 1 static - - 0 1 2 3 4 5 6 7 8 9 a
root@infix-06-0b-00:~$
The two IPv6 groups remain in the hardware database because the
port (x3) is notified of the host's membership twice: once via the
original event and once via a replay. Since only a single delete
notification is sent, the count remains at 1 when the bridge is
destroyed.
Then add the same port (or another port belonging to the same hardware
domain) to a new bridge, this time with snooping disabled:
root@infix-06-0b-00:~$ ip link add dev br1 up type bridge mcast_snooping 0 && \
> ip link set dev x3 up master br1
All multicast, including the two IPv6 groups from br0, should now be
flooded, according to the policy of br1. But instead the old
memberships are still active in the hardware database, causing the
switch to only forward traffic to those groups towards the CPU (port
0).
Eliminate the race in two steps:
1. Grab the write-side lock of the MDB while generating the replay
list.
This prevents new memberships from showing up while we are generating
the replay list. But it leaves the scenario in which a deferred event
was already generated, but not delivered, before we grabbed the
lock. Therefore:
2. Make sure that no deferred version of a replay event is already
enqueued to the switchdev deferred queue, before adding it to the
replay list, when replaying additions. |
| In the Linux kernel, the following vulnerability has been resolved:
vfio/pci: Lock external INTx masking ops
Mask operations through config space changes to DisINTx may race INTx
configuration changes via ioctl. Create wrappers that add locking for
paths outside of the core interrupt code.
In particular, irq_type is updated holding igate, therefore testing
is_intx() requires holding igate. For example clearing DisINTx from
config space can otherwise race changes of the interrupt configuration.
This aligns interfaces which may trigger the INTx eventfd into two
camps, one side serialized by igate and the other only enabled while
INTx is configured. A subsequent patch introduces synchronization for
the latter flows. |
| In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: fix race condition on enabling fast-xmit
fast-xmit must only be enabled after the sta has been uploaded to the driver,
otherwise it could end up passing the not-yet-uploaded sta via drv_tx calls
to the driver, leading to potential crashes because of uninitialized drv_priv
data.
Add a missing sta->uploaded check and re-check fast xmit after inserting a sta. |
| In the Linux kernel, the following vulnerability has been resolved:
mm/swap: fix race when skipping swapcache
When skipping swapcache for SWP_SYNCHRONOUS_IO, if two or more threads
swapin the same entry at the same time, they get different pages (A, B).
Before one thread (T0) finishes the swapin and installs page (A) to the
PTE, another thread (T1) could finish swapin of page (B), swap_free the
entry, then swap out the possibly modified page reusing the same entry.
It breaks the pte_same check in (T0) because PTE value is unchanged,
causing ABA problem. Thread (T0) will install a stalled page (A) into the
PTE and cause data corruption.
One possible callstack is like this:
CPU0 CPU1
---- ----
do_swap_page() do_swap_page() with same entry
<direct swapin path> <direct swapin path>
<alloc page A> <alloc page B>
swap_read_folio() <- read to page A swap_read_folio() <- read to page B
<slow on later locks or interrupt> <finished swapin first>
... set_pte_at()
swap_free() <- entry is free
<write to page B, now page A stalled>
<swap out page B to same swap entry>
pte_same() <- Check pass, PTE seems
unchanged, but page A
is stalled!
swap_free() <- page B content lost!
set_pte_at() <- staled page A installed!
And besides, for ZRAM, swap_free() allows the swap device to discard the
entry content, so even if page (B) is not modified, if swap_read_folio()
on CPU0 happens later than swap_free() on CPU1, it may also cause data
loss.
To fix this, reuse swapcache_prepare which will pin the swap entry using
the cache flag, and allow only one thread to swap it in, also prevent any
parallel code from putting the entry in the cache. Release the pin after
PT unlocked.
Racers just loop and wait since it's a rare and very short event. A
schedule_timeout_uninterruptible(1) call is added to avoid repeated page
faults wasting too much CPU, causing livelock or adding too much noise to
perf statistics. A similar livelock issue was described in commit
029c4628b2eb ("mm: swap: get rid of livelock in swapin readahead")
Reproducer:
This race issue can be triggered easily using a well constructed
reproducer and patched brd (with a delay in read path) [1]:
With latest 6.8 mainline, race caused data loss can be observed easily:
$ gcc -g -lpthread test-thread-swap-race.c && ./a.out
Polulating 32MB of memory region...
Keep swapping out...
Starting round 0...
Spawning 65536 workers...
32746 workers spawned, wait for done...
Round 0: Error on 0x5aa00, expected 32746, got 32743, 3 data loss!
Round 0: Error on 0x395200, expected 32746, got 32743, 3 data loss!
Round 0: Error on 0x3fd000, expected 32746, got 32737, 9 data loss!
Round 0 Failed, 15 data loss!
This reproducer spawns multiple threads sharing the same memory region
using a small swap device. Every two threads updates mapped pages one by
one in opposite direction trying to create a race, with one dedicated
thread keep swapping out the data out using madvise.
The reproducer created a reproduce rate of about once every 5 minutes, so
the race should be totally possible in production.
After this patch, I ran the reproducer for over a few hundred rounds and
no data loss observed.
Performance overhead is minimal, microbenchmark swapin 10G from 32G
zram:
Before: 10934698 us
After: 11157121 us
Cached: 13155355 us (Dropping SWP_SYNCHRONOUS_IO flag)
[kasong@tencent.com: v4] |
| In the Linux kernel, the following vulnerability has been resolved:
bpf: Fix racing between bpf_timer_cancel_and_free and bpf_timer_cancel
The following race is possible between bpf_timer_cancel_and_free
and bpf_timer_cancel. It will lead a UAF on the timer->timer.
bpf_timer_cancel();
spin_lock();
t = timer->time;
spin_unlock();
bpf_timer_cancel_and_free();
spin_lock();
t = timer->timer;
timer->timer = NULL;
spin_unlock();
hrtimer_cancel(&t->timer);
kfree(t);
/* UAF on t */
hrtimer_cancel(&t->timer);
In bpf_timer_cancel_and_free, this patch frees the timer->timer
after a rcu grace period. This requires a rcu_head addition
to the "struct bpf_hrtimer". Another kfree(t) happens in bpf_timer_init,
this does not need a kfree_rcu because it is still under the
spin_lock and timer->timer has not been visible by others yet.
In bpf_timer_cancel, rcu_read_lock() is added because this helper
can be used in a non rcu critical section context (e.g. from
a sleepable bpf prog). Other timer->timer usages in helpers.c
have been audited, bpf_timer_cancel() is the only place where
timer->timer is used outside of the spin_lock.
Another solution considered is to mark a t->flag in bpf_timer_cancel
and clear it after hrtimer_cancel() is done. In bpf_timer_cancel_and_free,
it busy waits for the flag to be cleared before kfree(t). This patch
goes with a straight forward solution and frees timer->timer after
a rcu grace period. |
| In the Linux kernel, the following vulnerability has been resolved:
mptcp: really cope with fastopen race
Fastopen and PM-trigger subflow shutdown can race, as reported by
syzkaller.
In my first attempt to close such race, I missed the fact that
the subflow status can change again before the subflow_state_change
callback is invoked.
Address the issue additionally copying with all the states directly
reachable from TCP_FIN_WAIT1. |
| In the Linux kernel, the following vulnerability has been resolved:
hv_netvsc: Fix race condition between netvsc_probe and netvsc_remove
In commit ac5047671758 ("hv_netvsc: Disable NAPI before closing the
VMBus channel"), napi_disable was getting called for all channels,
including all subchannels without confirming if they are enabled or not.
This caused hv_netvsc getting hung at napi_disable, when netvsc_probe()
has finished running but nvdev->subchan_work has not started yet.
netvsc_subchan_work() -> rndis_set_subchannel() has not created the
sub-channels and because of that netvsc_sc_open() is not running.
netvsc_remove() calls cancel_work_sync(&nvdev->subchan_work), for which
netvsc_subchan_work did not run.
netif_napi_add() sets the bit NAPI_STATE_SCHED because it ensures NAPI
cannot be scheduled. Then netvsc_sc_open() -> napi_enable will clear the
NAPIF_STATE_SCHED bit, so it can be scheduled. napi_disable() does the
opposite.
Now during netvsc_device_remove(), when napi_disable is called for those
subchannels, napi_disable gets stuck on infinite msleep.
This fix addresses this problem by ensuring that napi_disable() is not
getting called for non-enabled NAPI struct.
But netif_napi_del() is still necessary for these non-enabled NAPI struct
for cleanup purpose.
Call trace:
[ 654.559417] task:modprobe state:D stack: 0 pid: 2321 ppid: 1091 flags:0x00004002
[ 654.568030] Call Trace:
[ 654.571221] <TASK>
[ 654.573790] __schedule+0x2d6/0x960
[ 654.577733] schedule+0x69/0xf0
[ 654.581214] schedule_timeout+0x87/0x140
[ 654.585463] ? __bpf_trace_tick_stop+0x20/0x20
[ 654.590291] msleep+0x2d/0x40
[ 654.593625] napi_disable+0x2b/0x80
[ 654.597437] netvsc_device_remove+0x8a/0x1f0 [hv_netvsc]
[ 654.603935] rndis_filter_device_remove+0x194/0x1c0 [hv_netvsc]
[ 654.611101] ? do_wait_intr+0xb0/0xb0
[ 654.615753] netvsc_remove+0x7c/0x120 [hv_netvsc]
[ 654.621675] vmbus_remove+0x27/0x40 [hv_vmbus] |
| In the Linux kernel, the following vulnerability has been resolved:
xen/events: close evtchn after mapping cleanup
shutdown_pirq and startup_pirq are not taking the
irq_mapping_update_lock because they can't due to lock inversion. Both
are called with the irq_desc->lock being taking. The lock order,
however, is first irq_mapping_update_lock and then irq_desc->lock.
This opens multiple races:
- shutdown_pirq can be interrupted by a function that allocates an event
channel:
CPU0 CPU1
shutdown_pirq {
xen_evtchn_close(e)
__startup_pirq {
EVTCHNOP_bind_pirq
-> returns just freed evtchn e
set_evtchn_to_irq(e, irq)
}
xen_irq_info_cleanup() {
set_evtchn_to_irq(e, -1)
}
}
Assume here event channel e refers here to the same event channel
number.
After this race the evtchn_to_irq mapping for e is invalid (-1).
- __startup_pirq races with __unbind_from_irq in a similar way. Because
__startup_pirq doesn't take irq_mapping_update_lock it can grab the
evtchn that __unbind_from_irq is currently freeing and cleaning up. In
this case even though the event channel is allocated, its mapping can
be unset in evtchn_to_irq.
The fix is to first cleanup the mappings and then close the event
channel. In this way, when an event channel gets allocated it's
potential previous evtchn_to_irq mappings are guaranteed to be unset already.
This is also the reverse order of the allocation where first the event
channel is allocated and then the mappings are setup.
On a 5.10 kernel prior to commit 3fcdaf3d7634 ("xen/events: modify internal
[un]bind interfaces"), we hit a BUG like the following during probing of NVMe
devices. The issue is that during nvme_setup_io_queues, pci_free_irq
is called for every device which results in a call to shutdown_pirq.
With many nvme devices it's therefore likely to hit this race during
boot because there will be multiple calls to shutdown_pirq and
startup_pirq are running potentially in parallel.
------------[ cut here ]------------
blkfront: xvda: barrier or flush: disabled; persistent grants: enabled; indirect descriptors: enabled; bounce buffer: enabled
kernel BUG at drivers/xen/events/events_base.c:499!
invalid opcode: 0000 [#1] SMP PTI
CPU: 44 PID: 375 Comm: kworker/u257:23 Not tainted 5.10.201-191.748.amzn2.x86_64 #1
Hardware name: Xen HVM domU, BIOS 4.11.amazon 08/24/2006
Workqueue: nvme-reset-wq nvme_reset_work
RIP: 0010:bind_evtchn_to_cpu+0xdf/0xf0
Code: 5d 41 5e c3 cc cc cc cc 44 89 f7 e8 2b 55 ad ff 49 89 c5 48 85 c0 0f 84 64 ff ff ff 4c 8b 68 30 41 83 fe ff 0f 85 60 ff ff ff <0f> 0b 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 0f 1f 44 00 00
RSP: 0000:ffffc9000d533b08 EFLAGS: 00010046
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000006
RDX: 0000000000000028 RSI: 00000000ffffffff RDI: 00000000ffffffff
RBP: ffff888107419680 R08: 0000000000000000 R09: ffffffff82d72b00
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000000001ed
R13: 0000000000000000 R14: 00000000ffffffff R15: 0000000000000002
FS: 0000000000000000(0000) GS:ffff88bc8b500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000002610001 CR4: 00000000001706e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
? show_trace_log_lvl+0x1c1/0x2d9
? show_trace_log_lvl+0x1c1/0x2d9
? set_affinity_irq+0xdc/0x1c0
? __die_body.cold+0x8/0xd
? die+0x2b/0x50
? do_trap+0x90/0x110
? bind_evtchn_to_cpu+0xdf/0xf0
? do_error_trap+0x65/0x80
? bind_evtchn_to_cpu+0xdf/0xf0
? exc_invalid_op+0x4e/0x70
? bind_evtchn_to_cpu+0xdf/0xf0
? asm_exc_invalid_op+0x12/0x20
? bind_evtchn_to_cpu+0xdf/0x
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
blk-mq: fix IO hang from sbitmap wakeup race
In blk_mq_mark_tag_wait(), __add_wait_queue() may be re-ordered
with the following blk_mq_get_driver_tag() in case of getting driver
tag failure.
Then in __sbitmap_queue_wake_up(), waitqueue_active() may not observe
the added waiter in blk_mq_mark_tag_wait() and wake up nothing, meantime
blk_mq_mark_tag_wait() can't get driver tag successfully.
This issue can be reproduced by running the following test in loop, and
fio hang can be observed in < 30min when running it on my test VM
in laptop.
modprobe -r scsi_debug
modprobe scsi_debug delay=0 dev_size_mb=4096 max_queue=1 host_max_queue=1 submit_queues=4
dev=`ls -d /sys/bus/pseudo/drivers/scsi_debug/adapter*/host*/target*/*/block/* | head -1 | xargs basename`
fio --filename=/dev/"$dev" --direct=1 --rw=randrw --bs=4k --iodepth=1 \
--runtime=100 --numjobs=40 --time_based --name=test \
--ioengine=libaio
Fix the issue by adding one explicit barrier in blk_mq_mark_tag_wait(), which
is just fine in case of running out of tag. |
| In the Linux kernel, the following vulnerability has been resolved:
tracing: Ensure visibility when inserting an element into tracing_map
Running the following two commands in parallel on a multi-processor
AArch64 machine can sporadically produce an unexpected warning about
duplicate histogram entries:
$ while true; do
echo hist:key=id.syscall:val=hitcount > \
/sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/trigger
cat /sys/kernel/debug/tracing/events/raw_syscalls/sys_enter/hist
sleep 0.001
done
$ stress-ng --sysbadaddr $(nproc)
The warning looks as follows:
[ 2911.172474] ------------[ cut here ]------------
[ 2911.173111] Duplicates detected: 1
[ 2911.173574] WARNING: CPU: 2 PID: 12247 at kernel/trace/tracing_map.c:983 tracing_map_sort_entries+0x3e0/0x408
[ 2911.174702] Modules linked in: iscsi_ibft(E) iscsi_boot_sysfs(E) rfkill(E) af_packet(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ena(E) tiny_power_button(E) qemu_fw_cfg(E) button(E) fuse(E) efi_pstore(E) ip_tables(E) x_tables(E) xfs(E) libcrc32c(E) aes_ce_blk(E) aes_ce_cipher(E) crct10dif_ce(E) polyval_ce(E) polyval_generic(E) ghash_ce(E) gf128mul(E) sm4_ce_gcm(E) sm4_ce_ccm(E) sm4_ce(E) sm4_ce_cipher(E) sm4(E) sm3_ce(E) sm3(E) sha3_ce(E) sha512_ce(E) sha512_arm64(E) sha2_ce(E) sha256_arm64(E) nvme(E) sha1_ce(E) nvme_core(E) nvme_auth(E) t10_pi(E) sg(E) scsi_mod(E) scsi_common(E) efivarfs(E)
[ 2911.174738] Unloaded tainted modules: cppc_cpufreq(E):1
[ 2911.180985] CPU: 2 PID: 12247 Comm: cat Kdump: loaded Tainted: G E 6.7.0-default #2 1b58bbb22c97e4399dc09f92d309344f69c44a01
[ 2911.182398] Hardware name: Amazon EC2 c7g.8xlarge/, BIOS 1.0 11/1/2018
[ 2911.183208] pstate: 61400005 (nZCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[ 2911.184038] pc : tracing_map_sort_entries+0x3e0/0x408
[ 2911.184667] lr : tracing_map_sort_entries+0x3e0/0x408
[ 2911.185310] sp : ffff8000a1513900
[ 2911.185750] x29: ffff8000a1513900 x28: ffff0003f272fe80 x27: 0000000000000001
[ 2911.186600] x26: ffff0003f272fe80 x25: 0000000000000030 x24: 0000000000000008
[ 2911.187458] x23: ffff0003c5788000 x22: ffff0003c16710c8 x21: ffff80008017f180
[ 2911.188310] x20: ffff80008017f000 x19: ffff80008017f180 x18: ffffffffffffffff
[ 2911.189160] x17: 0000000000000000 x16: 0000000000000000 x15: ffff8000a15134b8
[ 2911.190015] x14: 0000000000000000 x13: 205d373432323154 x12: 5b5d313131333731
[ 2911.190844] x11: 00000000fffeffff x10: 00000000fffeffff x9 : ffffd1b78274a13c
[ 2911.191716] x8 : 000000000017ffe8 x7 : c0000000fffeffff x6 : 000000000057ffa8
[ 2911.192554] x5 : ffff0012f6c24ec0 x4 : 0000000000000000 x3 : ffff2e5b72b5d000
[ 2911.193404] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0003ff254480
[ 2911.194259] Call trace:
[ 2911.194626] tracing_map_sort_entries+0x3e0/0x408
[ 2911.195220] hist_show+0x124/0x800
[ 2911.195692] seq_read_iter+0x1d4/0x4e8
[ 2911.196193] seq_read+0xe8/0x138
[ 2911.196638] vfs_read+0xc8/0x300
[ 2911.197078] ksys_read+0x70/0x108
[ 2911.197534] __arm64_sys_read+0x24/0x38
[ 2911.198046] invoke_syscall+0x78/0x108
[ 2911.198553] el0_svc_common.constprop.0+0xd0/0xf8
[ 2911.199157] do_el0_svc+0x28/0x40
[ 2911.199613] el0_svc+0x40/0x178
[ 2911.200048] el0t_64_sync_handler+0x13c/0x158
[ 2911.200621] el0t_64_sync+0x1a8/0x1b0
[ 2911.201115] ---[ end trace 0000000000000000 ]---
The problem appears to be caused by CPU reordering of writes issued from
__tracing_map_insert().
The check for the presence of an element with a given key in this
function is:
val = READ_ONCE(entry->val);
if (val && keys_match(key, val->key, map->key_size)) ...
The write of a new entry is:
elt = get_free_elt(map);
memcpy(elt->key, key, map->key_size);
entry->val = elt;
The "memcpy(elt->key, key, map->key_size);" and "entry->val = elt;"
stores may become visible in the reversed order on another CPU. This
second CPU might then incorrectly determine that a new key doesn't match
an already present val->key and subse
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
fs/proc/task_mmu: move mmu notification mechanism inside mm lock
Move mmu notification mechanism inside mm lock to prevent race condition
in other components which depend on it. The notifier will invalidate
memory range. Depending upon the number of iterations, different memory
ranges would be invalidated.
The following warning would be removed by this patch:
WARNING: CPU: 0 PID: 5067 at arch/x86/kvm/../../../virt/kvm/kvm_main.c:734 kvm_mmu_notifier_change_pte+0x860/0x960 arch/x86/kvm/../../../virt/kvm/kvm_main.c:734
There is no behavioural and performance change with this patch when
there is no component registered with the mmu notifier.
[akpm@linux-foundation.org: narrow the scope of `range', per Sean] |
| In the Linux kernel, the following vulnerability has been resolved:
ALSA: pcm: Fix races among concurrent prealloc proc writes
We have no protection against concurrent PCM buffer preallocation
changes via proc files, and it may potentially lead to UAF or some
weird problem. This patch applies the PCM open_mutex to the proc
write operation for avoiding the racy proc writes and the PCM stream
open (and further operations). |
