Pull io_uring fix from Jens Axboe:
"Just a single fix for the commit that went into your tree yesterday,
which exposed an issue with not always clearing notifications. That
could cause them to be used more than once"
* tag 'io_uring-6.14-20250322' of git://git.kernel.dk/linux:
io_uring/net: fix sendzc double notif flush
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 5823 at lib/refcount.c:28 refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
RIP: 0010:refcount_warn_saturate+0x15a/0x1d0 lib/refcount.c:28
Call Trace:
<TASK>
io_notif_flush io_uring/notif.h:40 [inline]
io_send_zc_cleanup+0x121/0x170 io_uring/net.c:1222
io_clean_op+0x58c/0x9a0 io_uring/io_uring.c:406
io_free_batch_list io_uring/io_uring.c:1429 [inline]
__io_submit_flush_completions+0xc16/0xd20 io_uring/io_uring.c:1470
io_submit_flush_completions io_uring/io_uring.h:159 [inline]
Before the blamed commit, sendzc relied on io_req_msg_cleanup() to clear
REQ_F_NEED_CLEANUP, so after the following snippet the request will
never hit the core io_uring cleanup path.
io_notif_flush();
io_req_msg_cleanup();
The easiest fix is to null the notification. io_send_zc_cleanup() can
still be called after, but it's tolerated.
Reported-by: syzbot+cf285a028ffba71b2ef5@syzkaller.appspotmail.com
Tested-by: syzbot+cf285a028ffba71b2ef5@syzkaller.appspotmail.com
Fixes: cc34d8330e ("io_uring/net: don't clear REQ_F_NEED_CLEANUP unconditionally")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e1306007458b8891c88c4f20c966a17595f766b0.1742643795.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull io_uring fix from Jens Axboe:
"Single fix heading to stable, fixing an issue with io_req_msg_cleanup()
sometimes too eagerly clearing cleanup flags"
* tag 'io_uring-6.14-20250321' of git://git.kernel.dk/linux:
io_uring/net: don't clear REQ_F_NEED_CLEANUP unconditionally
io_req_msg_cleanup() relies on the fact that io_netmsg_recycle() will
always fully recycle, but that may not be the case if the msg cache
was already full. To ensure that normal cleanup always gets run,
let io_netmsg_recycle() deal with clearing the relevant cleanup flags,
as it knows exactly when that should be done.
Cc: stable@vger.kernel.org
Reported-by: David Wei <dw@davidwei.uk>
Fixes: 7519134178 ("io_uring/net: add iovec recycling")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull io_uring fix from Jens Axboe:
"A single fix for a regression introduced in the 6.14 merge window,
causing stalls/hangs with IOPOLL reads or writes"
* tag 'io_uring-6.14-20250306' of git://git.kernel.dk/linux:
io_uring/rw: ensure reissue path is correctly handled for IOPOLL
The IOPOLL path posts CQEs when the io_kiocb is marked as completed,
so it cannot rely on the usual retry that non-IOPOLL requests do for
read/write requests.
If -EAGAIN is received and the request should be retried, go through
the normal completion path and let the normal flush logic catch it and
reissue it, like what is done for !IOPOLL reads or writes.
Fixes: d803d12394 ("io_uring/rw: handle -EAGAIN retry at IO completion time")
Reported-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/io-uring/2b43ccfa-644d-4a09-8f8f-39ad71810f41@oracle.com/
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull io_uring fix from Jens Axboe:
"Just a single fix headed for stable, ensuring that msg_control is
properly saved in compat mode as well"
* tag 'io_uring-6.14-20250228' of git://git.kernel.dk/linux:
io_uring/net: save msg_control for compat
Pull io_uring fixes from Jens Axboe:
- Series fixing an issue with multishot read on pollable files that may
return -EIOCBQUEUED from ->read_iter(). Four small patches for that,
the first one deliberately done in such a way that it'd be easy to
backport
- Remove some dead constant definitions
- Use array_index_nospec() for opcode indexing
- Work-around for worker creation retries in the presence of signals
* tag 'io_uring-6.14-20250221' of git://git.kernel.dk/linux:
io_uring/rw: clean up mshot forced sync mode
io_uring/rw: move ki_complete init into prep
io_uring/rw: don't directly use ki_complete
io_uring/rw: forbid multishot async reads
io_uring/rsrc: remove unused constants
io_uring: fix spelling error in uapi io_uring.h
io_uring: prevent opcode speculation
io-wq: backoff when retrying worker creation
When io_uring submission goes async for the first time on a given task,
we'll try to create a worker thread to handle the submission. Creating
this worker thread can fail due to various transient conditions, such as
an outstanding signal in the forking thread, so we have retry logic with
a limit of 3 retries. However, this retry logic appears to be too
aggressive/fast - we've observed a thread blowing through the retry
limit while having the same outstanding signal the whole time. Here's an
excerpt of some tracing that demonstrates the issue:
First, signal 26 is generated for the process. It ends up getting routed
to thread 92942.
0) cbd-92284 /* signal_generate: sig=26 errno=0 code=-2 comm=psblkdASD pid=92934 grp=1 res=0 */
This causes create_io_thread in the signalled thread to fail with
ERESTARTNOINTR, and thus a retry is queued.
13) task_th-92942 /* io_uring_queue_async_work: ring 000000007325c9ae, request 0000000080c96d8e, user_data 0x0, opcode URING_CMD, flags 0x8240001, normal queue, work 000000006e96dd3f */
13) task_th-92942 io_wq_enqueue() {
13) task_th-92942 _raw_spin_lock();
13) task_th-92942 io_wq_activate_free_worker();
13) task_th-92942 _raw_spin_lock();
13) task_th-92942 create_io_worker() {
13) task_th-92942 __kmalloc_cache_noprof();
13) task_th-92942 __init_swait_queue_head();
13) task_th-92942 kprobe_ftrace_handler() {
13) task_th-92942 get_kprobe();
13) task_th-92942 aggr_pre_handler() {
13) task_th-92942 pre_handler_kretprobe();
13) task_th-92942 /* create_enter: (create_io_thread+0x0/0x50) fn=0xffffffff8172c0e0 arg=0xffff888996bb69c0 node=-1 */
13) task_th-92942 } /* aggr_pre_handler */
...
13) task_th-92942 } /* copy_process */
13) task_th-92942 } /* create_io_thread */
13) task_th-92942 kretprobe_rethook_handler() {
13) task_th-92942 /* create_exit: (create_io_worker+0x8a/0x1a0 <- create_io_thread) arg1=0xfffffffffffffdff */
13) task_th-92942 } /* kretprobe_rethook_handler */
13) task_th-92942 queue_work_on() {
...
The CPU is then handed to a kworker to process the queued retry:
------------------------------------------
13) task_th-92942 => kworker-54154
------------------------------------------
13) kworker-54154 io_workqueue_create() {
13) kworker-54154 io_queue_worker_create() {
13) kworker-54154 task_work_add() {
13) kworker-54154 wake_up_state() {
13) kworker-54154 try_to_wake_up() {
13) kworker-54154 _raw_spin_lock_irqsave();
13) kworker-54154 _raw_spin_unlock_irqrestore();
13) kworker-54154 } /* try_to_wake_up */
13) kworker-54154 } /* wake_up_state */
13) kworker-54154 kick_process();
13) kworker-54154 } /* task_work_add */
13) kworker-54154 } /* io_queue_worker_create */
13) kworker-54154 } /* io_workqueue_create */
And then we immediately switch back to the original task to try creating
a worker again. This fails, because the original task still hasn't
handled its signal.
-----------------------------------------
13) kworker-54154 => task_th-92942
------------------------------------------
13) task_th-92942 create_worker_cont() {
13) task_th-92942 kprobe_ftrace_handler() {
13) task_th-92942 get_kprobe();
13) task_th-92942 aggr_pre_handler() {
13) task_th-92942 pre_handler_kretprobe();
13) task_th-92942 /* create_enter: (create_io_thread+0x0/0x50) fn=0xffffffff8172c0e0 arg=0xffff888996bb69c0 node=-1 */
13) task_th-92942 } /* aggr_pre_handler */
13) task_th-92942 } /* kprobe_ftrace_handler */
13) task_th-92942 create_io_thread() {
13) task_th-92942 copy_process() {
13) task_th-92942 task_active_pid_ns();
13) task_th-92942 _raw_spin_lock_irq();
13) task_th-92942 recalc_sigpending();
13) task_th-92942 _raw_spin_lock_irq();
13) task_th-92942 } /* copy_process */
13) task_th-92942 } /* create_io_thread */
13) task_th-92942 kretprobe_rethook_handler() {
13) task_th-92942 /* create_exit: (create_worker_cont+0x35/0x1b0 <- create_io_thread) arg1=0xfffffffffffffdff */
13) task_th-92942 } /* kretprobe_rethook_handler */
13) task_th-92942 io_worker_release();
13) task_th-92942 queue_work_on() {
13) task_th-92942 clear_pending_if_disabled();
13) task_th-92942 __queue_work() {
13) task_th-92942 } /* __queue_work */
13) task_th-92942 } /* queue_work_on */
13) task_th-92942 } /* create_worker_cont */
The pattern repeats another couple times until we blow through the retry
counter, at which point we give up. All outstanding work is canceled,
and the io_uring command which triggered all this is failed with
ECANCELED:
13) task_th-92942 io_acct_cancel_pending_work() {
...
13) task_th-92942 /* io_uring_complete: ring 000000007325c9ae, req 0000000080c96d8e, user_data 0x0, result -125, cflags 0x0 extra1 0 extra2 0 */
Finally, the task gets around to processing its outstanding signal 26,
but it's too late.
13) task_th-92942 /* signal_deliver: sig=26 errno=0 code=-2 sa_handler=59566a0 sa_flags=14000000 */
Try to address this issue by adding a small scaling delay when retrying
worker creation. This should give the forking thread time to handle its
signal in the above case. This isn't a particularly satisfying solution,
as sufficiently paradoxical scheduling would still have us hitting the
same issue, and I'm open to suggestions for something better. But this
is likely to prevent this (already rare) issue from hitting in practice.
Signed-off-by: Uday Shankar <ushankar@purestorage.com>
Link: https://lore.kernel.org/r/20250208-wq_retry-v2-1-4f6f5041d303@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull io_uring fixes from Jens Axboe:
- fixes for a potential data corruption issue with IORING_OP_URING_CMD,
where not all the SQE data is stable. Will be revisited in the
future, for now it ends up with just always copying it beyond prep to
provide the same guarantees as all other opcodes
- make the waitid opcode setup async data like any other opcodes (no
real fix here, just a consistency thing)
- fix for waitid io_tw_state abuse
- when a buffer group is type is changed, do so by allocating a new
buffer group entry and discard the old one, rather than migrating
* tag 'io_uring-6.14-20250214' of git://git.kernel.dk/linux:
io_uring/uring_cmd: unconditionally copy SQEs at prep time
io_uring/waitid: setup async data in the prep handler
io_uring/uring_cmd: remove dead req_has_async_data() check
io_uring/uring_cmd: switch sqe to async_data on EAGAIN
io_uring/uring_cmd: don't assume io_uring_cmd_data layout
io_uring/kbuf: reallocate buf lists on upgrade
io_uring/waitid: don't abuse io_tw_state
This isn't generally necessary, but conditions have been observed where
SQE data is accessed from the original SQE after prep has been done and
outside of the initial issue. Opcode prep handlers must ensure that any
SQE related data is stable beyond the prep phase, but uring_cmd is a bit
special in how it handles the SQE which makes it susceptible to reading
stale data. If the application has reused the SQE before the original
completes, then that can lead to data corruption.
Down the line we can relax this again once uring_cmd has been sanitized
a bit, and avoid unnecessarily copying the SQE.
Fixes: 5eff57fa9f ("io_uring/uring_cmd: defer SQE copying until it's needed")
Reported-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Li Zetao <lizetao1@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This is the idiomatic way that opcodes should setup their async data,
so that it's always valid inside ->issue() without issue needing to
do that.
Fixes: f31ecf671d ("io_uring: add IORING_OP_WAITID support")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Any uring_cmd always has async data allocated now, there's no reason to
check and clear a cached copy of the SQE.
Fixes: d10f19dff5 ("io_uring/uring_cmd: switch to always allocating async data")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
5eff57fa9f ("io_uring/uring_cmd: defer SQE copying until it's needed")
moved the unconditional memcpy() of the uring_cmd SQE to async_data
to 2 cases when the request goes async:
- If REQ_F_FORCE_ASYNC is set to force the initial issue to go async
- If ->uring_cmd() returns -EAGAIN in the initial non-blocking issue
Unlike the REQ_F_FORCE_ASYNC case, in the EAGAIN case, io_uring_cmd()
copies the SQE to async_data but neglects to update the io_uring_cmd's
sqe field to point to async_data. As a result, sqe still points to the
slot in the userspace-mapped SQ. At the end of io_submit_sqes(), the
kernel advances the SQ head index, allowing userspace to reuse the slot
for a new SQE. If userspace reuses the slot before the io_uring worker
reissues the original SQE, the io_uring_cmd's SQE will be corrupted.
Introduce a helper io_uring_cmd_cache_sqes() to copy the original SQE to
the io_uring_cmd's async_data and point sqe there. Use it for both the
REQ_F_FORCE_ASYNC and EAGAIN cases. This ensures the uring_cmd doesn't
read from the SQ slot after it has been returned to userspace.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: 5eff57fa9f ("io_uring/uring_cmd: defer SQE copying until it's needed")
Link: https://lore.kernel.org/r/20250212204546.3751645-3-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
eaf72f7b41 ("io_uring/uring_cmd: cleanup struct io_uring_cmd_data
layout") removed most of the places assuming struct io_uring_cmd_data
has sqes as its first field. However, the EAGAIN case in io_uring_cmd()
still compares ioucmd->sqe to the struct io_uring_cmd_data pointer using
a void * cast. Since fa3595523d ("io_uring: get rid of alloc cache
init_once handling"), sqes is no longer io_uring_cmd_data's first field.
As a result, the pointers will always compare unequal and memcpy() may
be called with the same source and destination.
Replace the incorrect void * cast with the address of the sqes field.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Fixes: eaf72f7b41 ("io_uring/uring_cmd: cleanup struct io_uring_cmd_data layout")
Link: https://lore.kernel.org/r/20250212204546.3751645-2-csander@purestorage.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
IORING_REGISTER_PBUF_RING can reuse an old struct io_buffer_list if it
was created for legacy selected buffer and has been emptied. It violates
the requirement that most of the field should stay stable after publish.
Always reallocate it instead.
Cc: stable@vger.kernel.org
Reported-by: Pumpkin Chang <pumpkin@devco.re>
Fixes: 2fcabce2d7 ("io_uring: disallow mixed provided buffer group registrations")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
struct io_tw_state is managed by core io_uring, and opcode handling code
must never try to cheat and create their own instances, it's plain
incorrect.
io_waitid_complete() attempts exactly that outside of the task work
context, and even though the ring is locked, there would be no one to
reap the requests from the defer completion list. It only works now
because luckily it's called before io_uring_try_cancel_uring_cmd(),
which flushes completions.
Fixes: f31ecf671d ("io_uring: add IORING_OP_WAITID support")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull locking fix from Ingo Molnar:
"Fix a dangling pointer bug in the futex code used by the uring code.
It isn't causing problems at the moment due to uring ABI limitations
leaving it essentially unused in current usages, but is a good idea to
fix nevertheless"
* tag 'locking-urgent-2025-02-08' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
futex: Pass in task to futex_queue()
