| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| In the Linux kernel, the following vulnerability has been resolved:
RDMA/rxe: insert mcg into mcg_tree only after rxe_mcast_add() succeeds
rxe_get_mcg() publishes a newly allocated multicast group in
rxe->mcg_tree before programming the backing Ethernet multicast address
with rxe_mcast_add(), which runs outside mcg_lock. A local userspace
RDMA client reaches this path with ATTACH_MCAST on a UD QP; if
rxe_mcast_add() then returns an error (for example -ENODEV when the
backing netdev has been removed, or a propagated dev_mc_add() error),
the unwind frees the published group without removing it from the tree.
A later lookup of the same MGID dereferences the freed struct rxe_mcg
from __rxe_lookup_mcg().
Fix this by keeping the new mcg private until rxe_mcast_add() succeeds.
Split the tree publication into __rxe_publish_mcg(), call rxe_mcast_add()
before taking the tree reference, and free the still-private mcg on
failure. Because the group is never visible in mcg_tree until the
multicast address is programmed, no concurrent caller can look it up or
attach a QP to a group that is about to be torn down, so the error path
needs no conditional unwind. If another caller publishes the same MGID
while the address is being programmed, the post-add re-check under
mcg_lock finds the winner; this caller then drops its private object and
balances its own rxe_mcast_add() with rxe_mcast_del() before returning
the winner.
Reproduced by forcing the rxe_mcast_add() error return under KASAN:
without the change the next attach to the same MGID reports a
slab-use-after-free in __rxe_lookup_mcg(); with it the forced failure
returns cleanly. A no-injection attach/detach regression, including a
two-QP shared join/leave and re-attach, stays KASAN- and leak-clean. |
| In the Linux kernel, the following vulnerability has been resolved:
xfrm: add missing rcu_read_lock(), skb_dst_force() and dev_hold() for xfrm_trans_reinject()
syzbot reported a suspicious RCU usage warning in ip6_pkt_drop():
WARNING: suspicious RCU usage in ip6_pkt_drop
include/net/addrconf.h:389 suspicious rcu_dereference_check() usage!
Call Trace:
__in6_dev_get_safely include/net/addrconf.h:389 [inline]
ip6_pkt_drop+0x596/0x610 net/ipv6/route.c:4620
ip6_pkt_discard+0x1c/0x30 net/ipv6/route.c:4651
xfrm_trans_reinject+0x324/0x630 net/xfrm/xfrm_input.c:806
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
When commit 4f4920669d21 ("xfrm: Reinject transport-mode packets through
workqueue") converted xfrm_trans_reinject from a tasklet to a workqueue,
the reinjection loop ceased running in softirq context. Workqueue workers
run in process context where local_bh_disable() does not enter an RCU
read-side critical section under CONFIG_PREEMPT_RCU.
Because finish callbacks (such as ip6_rcv_finish) expect to run under an
RCU read lock (performing route lookups, l3mdev lookups, and accessing
RCU-protected data structures), invoking them in workqueue context without
rcu_read_lock() triggers RCU lockdep warnings.
Furthermore, packets queued to the workqueue via xfrm_trans_queue_net()
may carry non-refcounted (noref) dst entries (e.g. from ip_route_input_noref).
Additionally, on netdevice unregistration, dst_dev_put() replaces dst->dev
with blackhole_netdev, so dst entries do not keep skb->dev alive while
queued in the workqueue.
Fix these issues by:
1. Calling skb_dst_force(skb) in xfrm_trans_queue_net() while still in the
caller's RCU section to ensure dst is reference-counted before queuing.
2. Holding a reference on skb->dev via dev_hold()/dev_put() across workqueue
deferral so skb->dev remains valid during finish() callback processing.
3. Acquiring rcu_read_lock() around the finish callback invocation loop in
xfrm_trans_reinject(). |
| In the Linux kernel, the following vulnerability has been resolved:
net: lan743x: fix RX checksum use-after-free
lan743x_rx_process_buffer() adds each non-first receive buffer to the
head skb's frag_list. On the last descriptor, lan743x_rx_trim_skb()
linearizes the head and frees the fragment skb metadata.
The checksum-success path then writes ip_summed through the local skb
pointer, which still points to the final fragment. This causes a
use-after-free write when a packet spans more than one receive buffer.
Set ip_summed on the surviving head skb instead. Multi-buffer receive
can occur after a live MTU increase because existing ring entries keep
their old buffer size until they are replenished.
A KUnit test invoking lan743x_rx_process_buffer() with a two-buffer
packet produced a one-byte KASAN use-after-free write before this change.
The same test passed after the change. The driver object also builds
with W=1. This was not tested on physical LAN743x hardware. |
| In the Linux kernel, the following vulnerability has been resolved:
IB/isert: wait for deferred control PDU completions before releasing the connection
isert_send_done() hands ISTATE_SEND_TASKMGTRSP, ISTATE_SEND_REJECT and
ISTATE_SEND_TEXTRSP completions off to isert_comp_wq and returns. The work
item then runs isert_completion_put() -> isert_put_cmd(), which reads
isert_conn->conn and takes conn->cmd_lock.
Nothing orders that work item against teardown. isert_wait_conn() queues
isert_release_work, which frees isert_conn, and iscsit_close_connection()
frees the iscsit_conn right after it returns, so the queued work can run
against freed memory.
Count the deferred control PDU completions per connection and let
isert_wait_conn() wait for them before the release work is queued.
ISTATE_SEND_LOGOUTRSP is deliberately not counted: that branch runs
iscsit_logout_post_handler(), which ends up waiting for
conn->conn_wait_comp, and that completion is only sent by
iscsit_close_connection() after it has called iscsit_wait_conn().
Waiting for it here would deadlock. Its wait stays the existing
isert_wait4logout().
The splat below is from a kernel with tracing printk()s and an msleep(200)
injected into isert_do_control_comp() to widen the window:
BUG: KASAN: slab-use-after-free in isert_put_cmd+0x53d/0x620
Read of size 8 at addr ffff8881054f1038 by task kworker/u17:1/182
CPU: 0 UID: 0 PID: 182 Comm: kworker/u17:1 Tainted: G B 7.2.0-rc5-TWIDE-gb8babf08acc7 #1 PREEMPT(lazy)
Tainted: [B]=BAD_PAGE
Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Workqueue: isert_comp_wq isert_do_control_comp
Call Trace:
<TASK>
dump_stack_lvl+0x53/0x70
print_report+0xd0/0x630
? __pfx__raw_spin_lock_irqsave+0x10/0x10
? _raw_spin_unlock_irqrestore+0x3e/0x70
? isert_put_cmd+0x53d/0x620
kasan_report+0xce/0x100
? isert_put_cmd+0x53d/0x620
isert_put_cmd+0x53d/0x620
? isert_completion_put+0x305/0x330
? isert_do_control_comp+0x2ef/0x310
process_one_work+0x633/0x1030
? assign_work+0x11d/0x370
worker_thread+0x45b/0xd10
? __pfx_worker_thread+0x10/0x10
? __pfx_worker_thread+0x10/0x10
kthread+0x2c6/0x3b0
? recalc_sigpending+0x15c/0x1e0
? __pfx_kthread+0x10/0x10
ret_from_fork+0x36e/0x5a0
? __pfx_ret_from_fork+0x10/0x10
? __switch_to+0x572/0xdd0
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Allocated by task 48:
kasan_save_stack+0x33/0x60
kasan_save_track+0x14/0x30
__kasan_kmalloc+0x8f/0xa0
__kmalloc_cache_noprof+0x158/0x370
isert_cma_handler+0x1e3/0x2ae0
cma_cm_event_handler+0x3e/0x240
cma_ib_req_handler+0x17d9/0x4490
cm_process_work+0x41/0x330
cm_work_handler+0x5727/0xc160
process_one_work+0x633/0x1030
worker_thread+0x45b/0xd10
kthread+0x2c6/0x3b0
ret_from_fork+0x36e/0x5a0
ret_from_fork_asm+0x1a/0x30
Freed by task 184:
kasan_save_stack+0x33/0x60
kasan_save_track+0x14/0x30
kasan_save_free_info+0x3b/0x60
__kasan_slab_free+0x43/0x70
kfree+0x121/0x380
iscsit_close_connection+0x7cf/0x1e60
iscsit_take_action_for_connection_exit+0x1b6/0x360
iscsi_target_tx_thread+0x472/0x690
kthread+0x2c6/0x3b0
ret_from_fork+0x36e/0x5a0
ret_from_fork_asm+0x1a/0x30 |
| In the Linux kernel, the following vulnerability has been resolved:
cifs: Fix server use-after-free in cifs_chan_skip_or_disable()
When a secondary channel is no longer supported by the server,
cifs_chan_skip_or_disable() drops the channel reference with
cifs_put_tcp_session() and then continues to use the server pointer by
calling cifs_signal_cifsd_for_reconnect() on it and reading its
primary_server pointer. cifs_put_tcp_session() can drop the last
reference of the channel and tear it down, so both the channel and the
primary server (whose reference is also dropped by
cifs_put_tcp_session()) can be freed before they are signaled for
reconnect.
Signal the channel and the primary server and capture the primary
server pointer before dropping the channel reference with
cifs_put_tcp_session(). |
| In the Linux kernel, the following vulnerability has been resolved:
signal: Prevent exec() race
Hyunwoo debugged the following KASAN UAF splat:
BUG: KASAN: slab-use-after-free in __send_signal_locked+0xb27/0xba0
Write of size 8 at addr ffff888007ed80c8 by task poc/79
...
Call Trace:
__send_signal_locked+0xb27/0xba0
do_send_sig_info+0xa7/0x160
do_send_specific+0x76/0xa0
__x64_sys_tgkill+0x193/0x270
...
Allocated by task 80:
do_timer_create+0x1a4/0x1030
__x64_sys_timer_create+0x145/0x190
...
Freed by task 12:
kmem_cache_free_bulk+0x1f8/0x4a0
kvfree_rcu_bulk+0x14f/0x1c0
kfree_rcu_work+0x128/0x1a0
...
Last potentially related work creation:
kvfree_call_rcu+0x39/0x390
__flush_itimer_signals+0x211/0x320
flush_itimer_signals+0x47/0x90
begin_new_exec+0xa6b/0x28c0
It turned out that this happens with a non-leader exec() as Hyunwoo
explained:
de_thread() calls exchange_tids() before release_task(leader), so the
struct pid held by a SIGEV_THREAD_ID timer created against the leader's tid
now points to the thread which called execve(). pid_task() returns that
thread and lock_task_sighand() on it succeeds.
If the timer signal is blocked, its sigqueue stays queued on the leader's
task::pending. The next expiry of that timer can then run while
release_task() flushes the queue.
posixtimer_send_sigqueue() checks whether the sigqueue is already queued
with a plain list_empty(), which only reads list_head::next.
list_del_init() is not atomic and INIT_LIST_HEAD() stores list_head::next
before list_head::prev, so the check can pass in between. list_add_tail()
queues the entry on the task::pending of the live thread, and the
list_head::prev store from the flush then overwrites the list_head::prev
link that list_add_tail() has just set.
__flush_itimer_signals() does not undo that either. With list_head::prev
pointing at the entry itself, its list_del_init() only stores the same
values again, so the entry is not removed from the list. It is still there
after the last reference is dropped and the timer is freed by RCU, and the
list_add_tail() of a later tgkill() follows that list_head::prev into the
freed timer.
This problem surfaced with the recent commit which moved the sigqueue flush
out of the sighand lock held region.
Hyonwoo proposed to fix this by using list_del_init_careful(), but that
just papers over the problem. After some disucssions and various attempts
to solve it, Eric pointed out that there is no reason to flush
task::pending late in release_task() and it should be done in
exit_signals() already.
As nothing can collect and deliver signals which are queued in a dying
task's pending queue, there is no reason to delay it further.
But it has to be ensured that no signals can be queued into it after that
point. exit_signals() sets PF_EXITING in task::flags, which can be used as
an indicator for this.
Cure it by:
- Preventing signal queueing for task private signals (PIDTYPE_PID) when
the task has PF_EXITING set in __send_signal_locked() and in
posixtimer_send_sigqueue().
- Protecting the unlocked setting of PF_EXITING in exit_signals() for the
task group empty and the group exit case with sighand lock
- Flushing task::pending signals right there.
Optimize that by moving the whole pending list to an on-stack list head
under sighand lock and free the signals without the lock held.
There has been quite some discussion about the lockless flush and the
non-leader exec case on weakly ordered systems. The problem is that a third
party which tries to send a posix timer signal relies on the PID lookup to
find the target task and that lookup might result in the new leader when
the signal was originaly directed to the old leader. In case that the
signal was queued on the old leader then the lockless flush raised a
concern over the following situation:
old_leader new_leader third party
A: flush_list() // list_del_in
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
netfilter: flowtable: hold reference on ct until flow is released
nf_ct_put() releases the ct->ext area inmediately, the rcu typesafe
semantics also allow to refer to the wrong conntrack from the flowtable
datapath. Hold reference on ct until flow is released after rcu grace
period.
Add rcu_barrier() on module exit path, to ensure pending flow entries
are release before module goes away. |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_sync: Serialize local codec list cleanup
hci_dev_close_sync() clears hdev->local_codecs after releasing hdev->lock.
Codec list additions and both traversals in sco_sock_getsockopt() use that
lock, but the close path does not. A close and BT_CODEC query can therefore
interleave as follows:
hci_dev_close_sync() sco_sock_getsockopt()
hci_dev_lock()
fetch codec entry
hci_codec_list_clear()
kfree(entry)
read entry->id
The reader then accesses an entry which the close path has freed. KASAN
BUG: KASAN: slab-use-after-free in sco_sock_getsockopt+0xfa0/0xfe0
Read of size 1 at addr ffff8881001c3450
Call Trace:
sco_sock_getsockopt+0xfa0/0xfe0
do_sock_getsockopt+0x537/0x7b0
__sys_getsockopt+0xf2/0x170
Allocated by task 92:
hci_codec_list_add.isra.0+0x2c/0x440
hci_read_codec_capabilities+0x224/0x590
hci_read_supported_codecs+0x2c2/0x640
Freed by task 92:
kfree+0x131/0x3c0
hci_codec_list_clear+0xd8/0x160
hci_dev_close_sync+0x92a/0xfa0
Take hdev->lock around the clear operation at its existing point in the
close path. This makes the clear wait for active readers and prevents a new
traversal until the list is empty without changing teardown ordering. |
| In the Linux kernel, the following vulnerability has been resolved:
xfrm: save input state data before secpath resets
xfrm_input() stores the current xfrm_state in the skb secpath while it
continues receive-side processing. Some input paths can reset that secpath
before xfrm_input() has finished dereferencing the state.
Receive callback users such as VTI and XFRM interfaces can reset the
secpath. The VTI receive path does so before checking whether the packet
crosses network namespaces, while the XFRM interface path does so only for
cross-network-namespace packets. The XFRM_MAX_DEPTH error path can also
reset the secpath before the final drop callback reports the current
state's protocol.
If secpath_reset() drops the last state reference while the state is
concurrently deleted, xfrm_input() can still dereference the freed state
when selecting transport_finish() or reporting the drop callback protocol.
Save the state protocol on the stack while the state is still valid,
and use the already saved address family for transport_finish(). A larval
XFRM_STATE_ACQ state has no type, so retain nexthdr as its protocol. This
preserves the existing drop-path fallback while avoiding the post-reset
state dereferences without adding an extra state reference to every
received packet. |
| In the Linux kernel, the following vulnerability has been resolved:
IB/mlx4: Fix use-after-free on pkey sysfs registration failure
register_pkey_tree() ignores errors from register_one_pkey_tree() and
continues registering the remaining slaves. The per-slave error path has
already released the pkey parent kobjects, but their pointers remain
stored in the device. A later device cleanup therefore passes the stale
pointers to kobject_put(), causing a use-after-free.
Clear the parent pointers after releasing a failed slave tree and skip
unregistered trees during device cleanup. This preserves the existing
best-effort registration behavior while preventing a second cleanup of
the failed tree. |
| In the Linux kernel, the following vulnerability has been resolved:
xfrm: serialize state GC with device state flush
The deferred-device pass in xfrm_dev_state_flush() finds states under
xfrm_state_dev_gc_lock, but drops the lock before calling
xfrm_dev_state_free() because the driver callback may sleep. The device
GC list does not hold an xfrm_state reference, so the state GC worker can
destroy the same state concurrently.
The race can proceed as follows:
CPU 0 CPU 1
find x on the device GC list
drop xfrm_state_dev_gc_lock
read x->xso.dev
xfrm_state_gc_destroy(x)
xfrm_dev_state_free(x)
xfrm_state_free(x)
continue xfrm_dev_state_free(x)
Both paths can invoke the driver callback and drop the device reference.
CPU 0 can also access the xfrm_state after CPU 1 has freed it.
KASAN reported:
BUG: KASAN: slab-use-after-free in xfrm_dev_state_free+0x24c/0x2a0
Read of size 8 at addr ffff88810bbaa960 by task poc/102
Call Trace:
xfrm_dev_state_free+0x24c/0x2a0
xfrm_dev_state_flush+0x353/0x400
xfrm_dev_event+0x26d/0x3a0
notifier_call_chain+0xc0/0x280
__dev_notify_flags+0x169/0x250
netif_change_flags+0xe7/0x160
dev_change_flags+0x96/0x220
devinet_ioctl+0x7f4/0x1880
Allocated by task 87:
xfrm_state_alloc+0x1e/0x5c0
xfrm_add_sa+0xe7f/0x5820
xfrm_user_rcv_msg+0x4f3/0x940
Freed by task 57:
kmem_cache_free+0xcb/0x3d0
xfrm_state_gc_task+0x4a8/0x650
process_one_work+0x63a/0x1070
Serialize xfrm_state destruction against the deferred-device pass with a
mutex. Keep xfrm_state_dev_gc_lock limited to list operations and retain
the existing callback and device-reference release ordering. |
| In the Linux kernel, the following vulnerability has been resolved:
xfrm: fix compat ALLOCSPI request use-after-free
xfrm_state_netlink() builds the ALLOCSPI response with
dump_one_state(), which already calls alloc_compat() with the response
skb and header.
xfrm_alloc_userspi() then calls alloc_compat() again, but passes the
original request skb and its header. For a compat request, the
translator therefore interprets the 228-byte compat xfrm_userspi_info
as the 232-byte native layout and reads four bytes past the declared
payload. It also publishes the translated child through the request's
frag_list.
A multicast clone of the request shares skb_shared_info and can observe
that child. xfrm_user_rcv_msg() frees it after the request handler
returns, racing a compat receiver which may still be copying from it and
resulting in a use-after-free.
Remove the redundant conversion. The response keeps its correct compat
translation from dump_one_state(), and no child is attached to the
inbound request. |
| In the Linux kernel, the following vulnerability has been resolved:
x86/kprobes: Fix crash when probing CS CALL instructions
When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.
The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:
<__hrtimer_run_queues+249>: nopl 0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>: mov %r14,%rdi
<__hrtimer_run_queues+257>: cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>: mov %eax,%r12d
<__hrtimer_run_queues+266>: xchg %ax,%ax
<__hrtimer_run_queues+268>: mov %r13,%rdi
Which triggers this crash:
BUG: unable to handle page fault for address: 00000000000f41c9
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0
Oops: 0002 [#1] SMP NOPTI
CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
RIP: 0010:__hrtimer_run_queues+0x106/0x230
Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.
The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.
During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.
Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.
[ mingo: Refined the changelog ] |
| In the Linux kernel, the following vulnerability has been resolved:
wifi: brcmsmac: fix UAF in brcms_free_timer()
brcms_free_timer() calls brcms_del_timer() which uses the non-synchronous
cancel_delayed_work() to cancel the timer's underlying delayed work. If
the work callback (_brcms_timer) is already running, cancel_delayed_work()
returns false without waiting, and brcms_free_timer() proceeds to kfree(t)
while the callback still accesses t through container_of().
Add an explicit cancel_delayed_work_sync() after brcms_del_timer() to
guarantee that any in-flight callback has completed before the timer
structure is freed. |
| In the Linux kernel, the following vulnerability has been resolved:
net: bcmasp: clear txcb->last before writing each descriptor
bcmasp_xmit() only wrote txcb->last = true for the final fragment
of an SKB; non-final fragments left the field untouched. If a
descriptor slot was reused while it still held a stale true from
a previous SKB (possible when tx_spb_ring_full() underreported
fullness), bcmasp_tx_reclaim() would see last == true mid-SKB and
call dev_consume_skb_any() prematurely, freeing the sk_buff while
its remaining fragments were still in flight.
Unconditionally clear txcb->last before the conditional set so every
descriptor slot starts from a known false state regardless of what a
prior transmission left behind. |
| Use after free in mod_auth_digest in Apache Software Foundation Apache HTTP Server before 2.4.69 on all platforms allows an unauthenticated remote client to cause authentication state corruption via concurrent Digest authentication requests when AuthDigestNcCheck is enabled or AuthDigestNonceLifetime is set to 0.
Users are recommended to upgrade to version 2.4.69, which fixes this issue. |
| In the Linux kernel, the following vulnerability has been resolved:
netfilter: nfnetlink_log: wait for rcu grace period before freeing pernet state
sashiko reports: "nfnl_log_net_exit() calls nf_log_unset(), which
clears the logger pointer without an RCU grace period. Immediately after,
ops_free_list() frees the per-net state while concurrent packets might
still be executing nf_log_packet() under rcu_read_lock()."
Clear the pointer via .pre_exit to make sure rcu readers have completed
before pernet storage is free'd. The change in nf_log_syslog.c is only
done for consistency: it doesn't use pernet data. |
| In the Linux kernel, the following vulnerability has been resolved:
bpf: reject BPF_PSEUDO_FUNC reference to the main program
fixups.c:jit_subprogs() rewrites BPF_PSEUDO_FUNC loads to contain real
function addresses. This function is invoked from bpf_jit_subprogs()
only when env->subprog_cnt > 1. Meaning that for any program like
below:
int main(void *ctx) {
void *ptr = main;
...
bpf_timer_set_callback(..., ptr);
...
}
The 'ptr' won't be ever converted to contain an address.
In combination with e.g. bpf_timer_set_callback() this would lead to a
function call at a bogus address.
Instead of complicating the implementation, just assume that no useful
program needs main to be a sync or async callback and reject
BPF_PSEUDO_FUNC loads for the main subprogram. |
| In the Linux kernel, the following vulnerability has been resolved:
net/rds: use wq_has_sleeper() in release_in_xmit()
release_in_xmit() clears RDS_IN_XMIT with clear_bit_unlock() and then
checks waitqueue_active() to decide whether anyone needs waking.
clear_bit_unlock() is only a release operation: it orders the
critical section before the bit clear, but does not order the
subsequent plain load of the wait queue head after it. The waiter
side does the mirror image - it adds itself to the wait queue and
then tests the bit. That is the classic store-buffering pattern: the
releasing CPU can read the wait queue as empty while the waiting CPU
still reads the bit as set, so the sleeper is never woken.
The waiters are rds_conn_shutdown() and rds_tcp_reset_callbacks(),
both in uninterruptible wait_event() with no timeout. A lost wake-up
strands the shutdown worker on its single-threaded workqueue until
some other sender releases the bit again - and on a connection that
is being torn down precisely because it failed, there may never be
another sender.
The barrier used to be there: release_in_xmit() did clear_bit()
followed by smp_mb__after_atomic() until commit 1422f28826d2 ("rds:
introduce acquire/release ordering in acquire/release_in_xmit()")
folded both into clear_bit_unlock(), which strengthened the lock
hand-off but silently dropped the full barrier the wake-up check
depends on. The refill counterpart, release_refill() in
net/rds/ib_recv.c, still carries its smp_mb__after_atomic() for
exactly this reason.
Use wq_has_sleeper(), which is waitqueue_active() preceded by the
required full barrier. |
| In the Linux kernel, the following vulnerability has been resolved:
nexthop: Initialize extack in remove_nh_grp_entry()
remove_nh_grp_entry() prints the extack message when a listener fails
to replace the reduced nexthop group. However, extack is not
initialized and listeners are not required to set a message when
returning an error. Neither netdevsim nor mlxsw do so when an
allocation fails, resulting in the dereference of an uninitialized
stack pointer.
Fix by zero-initializing extack, as was done in commit 6347c5314cee
("nexthop: initialize extack in nh_res_bucket_migrate()"). |
