Merge tag 'io_uring-6.13-20250116' of git://git.kernel.dk/linux

Pull io_uring fixes from Jens Axboe:
"One fix for the error handling in buffer cloning, and one fix for the
ring resizing.

Two m

Merge tag 'io_uring-6.13-20250116' of git://git.kernel.dk/linux

Pull io_uring fixes from Jens Axboe:
"One fix for the error handling in buffer cloning, and one fix for the
ring resizing.

Two minor followups for the latter as well.

Both of these issues only affect 6.13, so not marked for stable"

* tag 'io_uring-6.13-20250116' of git://git.kernel.dk/linux:
io_uring/register: cache old SQ/CQ head reading for copies
io_uring/register: document io_register_resize_rings() shared mem usage
io_uring/register: use stable SQ/CQ ring data during resize
io_uring/rsrc: fixup io_clone_buffers() error handling

show more ...

io_uring/register: cache old SQ/CQ head reading for copies

The SQ and CQ ring heads are read twice - once for verifying that it's
within bounds, and once inside the loops copying SQE and CQE entries

io_uring/register: cache old SQ/CQ head reading for copies

The SQ and CQ ring heads are read twice - once for verifying that it's
within bounds, and once inside the loops copying SQE and CQE entries.
This is technically incorrect, in case the values could get modified
in between verifying them and using them in the copy loop. While this
won't lead to anything truly nefarious, it may cause longer loop times
for the copies than expected.

Read the ring head values once, and use the verified value in the copy
loops.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring/register: document io_register_resize_rings() shared mem usage

It can be a bit hard to tell which parts of io_register_resize_rings()
are operating on shared memory, and which ones are not.

io_uring/register: document io_register_resize_rings() shared mem usage

It can be a bit hard to tell which parts of io_register_resize_rings()
are operating on shared memory, and which ones are not. And anything
reading or writing to those regions should really use the read/write
once primitives.

Hence add those, ensuring sanity in how this memory is accessed, and
helping document the shared nature of it.

Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring/register: use stable SQ/CQ ring data during resize

Normally the kernel would not expect an application to modify any of
the data shared with the kernel during a resize operation, but of
cou

io_uring/register: use stable SQ/CQ ring data during resize

Normally the kernel would not expect an application to modify any of
the data shared with the kernel during a resize operation, but of
course the kernel cannot always assume good intent on behalf of the
application.

As part of resizing the rings, existing SQEs and CQEs are copied over
to the new storage. Resizing uses the masks in the newly allocated
shared storage to index the arrays, however it's possible that malicious
userspace could modify these after they have been sanity checked.

Use the validated and locally stored CQ and SQ ring sizing for masking
to ensure the values are both stable and valid.

Fixes: 79cfe9e59c2a ("io_uring/register: add IORING_REGISTER_RESIZE_RINGS")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring/rsrc: fixup io_clone_buffers() error handling

Jann reports he can trigger a UAF if the target ring unregisters
buffers before the clone operation is fully done. And additionally
also an iss

io_uring/rsrc: fixup io_clone_buffers() error handling

Jann reports he can trigger a UAF if the target ring unregisters
buffers before the clone operation is fully done. And additionally
also an issue related to node allocation failures. Both of those
stemp from the fact that the cleanup logic puts the buffers manually,
rather than just relying on io_rsrc_data_free() doing it. Hence kill
the manual cleanup code and just let io_rsrc_data_free() handle it,
it'll put the nodes appropriately.

Reported-by: Jann Horn <jannh@google.com>
Fixes: 3597f2786b68 ("io_uring/rsrc: unify file and buffer resource tables")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

Merge tag 'io_uring-6.13-20250111' of git://git.kernel.dk/linux

Pull io_uring fixes from Jens Axboe:

- Fix for multishot timeout updates only using the updated value for
the first invocation, n

Merge tag 'io_uring-6.13-20250111' of git://git.kernel.dk/linux

Pull io_uring fixes from Jens Axboe:

- Fix for multishot timeout updates only using the updated value for
the first invocation, not subsequent ones

- Silence a false positive lockdep warning

- Fix the eventfd signaling and putting RCU logic

- Fix fault injected SQPOLL setup not clearing the task pointer in the
error path

- Fix local task_work looking at the SQPOLL thread rather than just
signaling the safe variant. Again one of those theoretical issues,
which should be closed up none the less.

* tag 'io_uring-6.13-20250111' of git://git.kernel.dk/linux:
io_uring: don't touch sqd->thread off tw add
io_uring/sqpoll: zero sqd->thread on tctx errors
io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period
io_uring: silence false positive warnings
io_uring/timeout: fix multishot updates

show more ...

io_uring: don't touch sqd->thread off tw add

With IORING_SETUP_SQPOLL all requests are created by the SQPOLL task,
which means that req->task should always match sqd->thread. Since
accesses to sqd->

io_uring: don't touch sqd->thread off tw add

With IORING_SETUP_SQPOLL all requests are created by the SQPOLL task,
which means that req->task should always match sqd->thread. Since
accesses to sqd->thread should be separately protected, use req->task
in io_req_normal_work_add() instead.

Note, in the eyes of io_req_normal_work_add(), the SQPOLL task struct
is always pinned and alive, and sqd->thread can either be the task or
NULL. It's only problematic if the compiler decides to reload the value
after the null check, which is not so likely.

Cc: stable@vger.kernel.org
Cc: Bui Quang Minh <minhquangbui99@gmail.com>
Reported-by: lizetao <lizetao1@huawei.com>
Fixes: 78f9b61bd8e54 ("io_uring: wake SQPOLL task when task_work is added to an empty queue")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1cbbe72cf32c45a8fee96026463024cd8564a7d7.1736541357.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring/sqpoll: zero sqd->thread on tctx errors

Syzkeller reports:

BUG: KASAN: slab-use-after-free in thread_group_cputime+0x409/0x700 kernel/sched/cputime.c:341
Read of size 8 at addr ffff8880357

io_uring/sqpoll: zero sqd->thread on tctx errors

Syzkeller reports:

BUG: KASAN: slab-use-after-free in thread_group_cputime+0x409/0x700 kernel/sched/cputime.c:341
Read of size 8 at addr ffff88803578c510 by task syz.2.3223/27552
Call Trace:
<TASK>
...
kasan_report+0x143/0x180 mm/kasan/report.c:602
thread_group_cputime+0x409/0x700 kernel/sched/cputime.c:341
thread_group_cputime_adjusted+0xa6/0x340 kernel/sched/cputime.c:639
getrusage+0x1000/0x1340 kernel/sys.c:1863
io_uring_show_fdinfo+0xdfe/0x1770 io_uring/fdinfo.c:197
seq_show+0x608/0x770 fs/proc/fd.c:68
...

That's due to sqd->task not being cleared properly in cases where
SQPOLL task tctx setup fails, which can essentially only happen with
fault injection to insert allocation errors.

Cc: stable@vger.kernel.org
Fixes: 1251d2025c3e1 ("io_uring/sqpoll: early exit thread if task_context wasn't allocated")
Reported-by: syzbot+3d92cfcfa84070b0a470@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/efc7ec7010784463b2e7466d7b5c02c2cb381635.1736519461.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

Merge tag 'vfs-6.13-rc7.fixes.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:
"afs:

- Fix the maximum cell name length

- Fix merge prefere

Merge tag 'vfs-6.13-rc7.fixes.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:
"afs:

- Fix the maximum cell name length

- Fix merge preference rule failure condition

fuse:

- Fix fuse_get_user_pages() so it doesn't risk misleading the caller
to think pages have been allocated when they actually haven't

- Fix direct-io folio offset and length calculation

netfs:

- Fix async direct-io handling

- Fix read-retry for filesystems that don't provide a
->prepare_read() method

vfs:

- Prevent truncating 64-bit offsets to 32-bits in iomap

- Fix memory barrier interactions when polling

- Remove MNT_ONRB to fix concurrent modification of @mnt->mnt_flags
leading to MNT_ONRB to not be raised and invalid access to a list
member"

* tag 'vfs-6.13-rc7.fixes.2' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
poll: kill poll_does_not_wait()
sock_poll_wait: kill the no longer necessary barrier after poll_wait()
io_uring_poll: kill the no longer necessary barrier after poll_wait()
poll_wait: kill the obsolete wait_address check
poll_wait: add mb() to fix theoretical race between waitqueue_active() and .poll()
afs: Fix merge preference rule failure condition
netfs: Fix read-retry for fs with no ->prepare_read()
netfs: Fix kernel async DIO
fs: kill MNT_ONRB
iomap: avoid avoid truncating 64-bit offset to 32 bits
afs: Fix the maximum cell name length
fuse: Set *nbytesp=0 in fuse_get_user_pages on allocation failure
fuse: fix direct io folio offset and length calculation

show more ...

Merge branch 'vfs-6.14.poll' into vfs.fixes

Bring in the fixes for __pollwait() and waitqueue_active() interactions.

Signed-off-by: Christian Brauner <brauner@kernel.org>

io_uring_poll: kill the no longer necessary barrier after poll_wait()

Now that poll_wait() provides a full barrier we can remove smp_rmb() from
io_uring_poll().

In fact I don't think smp_rmb() was

io_uring_poll: kill the no longer necessary barrier after poll_wait()

Now that poll_wait() provides a full barrier we can remove smp_rmb() from
io_uring_poll().

In fact I don't think smp_rmb() was correct, it can't serialize LOADs and
STOREs.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250107162730.GA18940@redhat.com
Signed-off-by: Christian Brauner <brauner@kernel.org>

show more ...

Merge tag 'for-6.13-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
"A few more fixes.

Besides the one-liners in Btrfs there's fix to th

Merge tag 'for-6.13-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
"A few more fixes.

Besides the one-liners in Btrfs there's fix to the io_uring and
encoded read integration (added in this development cycle). The update
to io_uring provides more space for the ongoing command that is then
used in Btrfs to handle some cases.

- io_uring and encoded read:
- provide stable storage for io_uring command data
- make a copy of encoded read ioctl call, reuse that in case the
call would block and will be called again

- properly initialize zlib context for hardware compression on s390

- fix max extent size calculation on filesystems with non-zoned
devices

- fix crash in scrub on crafted image due to invalid extent tree"

* tag 'for-6.13-rc6-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: zlib: fix avail_in bytes for s390 zlib HW compression path
btrfs: zoned: calculate max_extent_size properly on non-zoned setup
btrfs: avoid NULL pointer dereference if no valid extent tree
btrfs: don't read from userspace twice in btrfs_uring_encoded_read()
io_uring: add io_uring_cmd_get_async_data helper
io_uring/cmd: add per-op data to struct io_uring_cmd_data
io_uring/cmd: rename struct uring_cache to io_uring_cmd_data

show more ...

io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period

io_eventfd_do_signal() is invoked from an RCU callback, but when
dropping the reference to the io_ev_fd, it calls io_eventfd_fr

io_uring/eventfd: ensure io_eventfd_signal() defers another RCU period

io_eventfd_do_signal() is invoked from an RCU callback, but when
dropping the reference to the io_ev_fd, it calls io_eventfd_free()
directly if the refcount drops to zero. This isn't correct, as any
potential freeing of the io_ev_fd should be deferred another RCU grace
period.

Just call io_eventfd_put() rather than open-code the dec-and-test and
free, which will correctly defer it another RCU grace period.

Fixes: 21a091b970cd ("io_uring: signal registered eventfd to process deferred task work")
Reported-by: Jann Horn <jannh@google.com>
Cc: stable@vger.kernel.org
Tested-by: Li Zetao <lizetao1@huawei.com>
Reviewed-by: Li Zetao<lizetao1@huawei.com>
Reviewed-by: Prasanna Kumar T S M <ptsm@linux.microsoft.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring: silence false positive warnings

If we kill a ring and then immediately exit the task, we'll get
cancellattion running by the task and a kthread in io_ring_exit_work.
For DEFER_TASKRUN, we

io_uring: silence false positive warnings

If we kill a ring and then immediately exit the task, we'll get
cancellattion running by the task and a kthread in io_ring_exit_work.
For DEFER_TASKRUN, we do want to limit it to only one entity executing
it, however it's currently not an issue as it's protected by uring_lock.

Silence lockdep assertions for now, we'll return to it later.

Reported-by: syzbot+1bcb75613069ad4957fc@syzkaller.appspotmail.com
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/7e5f68281acb0f081f65fde435833c68a3b7e02f.1736257837.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring/cmd: add per-op data to struct io_uring_cmd_data

In case an op handler for ->uring_cmd() needs stable storage for user
data, it can allocate io_uring_cmd_data->op_data and use it for the
du

io_uring/cmd: add per-op data to struct io_uring_cmd_data

In case an op handler for ->uring_cmd() needs stable storage for user
data, it can allocate io_uring_cmd_data->op_data and use it for the
duration of the request. When the request gets cleaned up, uring_cmd
will free it automatically.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

io_uring/cmd: rename struct uring_cache to io_uring_cmd_data

In preparation for making this more generically available for
->uring_cmd() usage that needs stable command data, rename it and move
it t

io_uring/cmd: rename struct uring_cache to io_uring_cmd_data

In preparation for making this more generically available for
->uring_cmd() usage that needs stable command data, rename it and move
it to io_uring/cmd.h instead.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: David Sterba <dsterba@suse.com>

show more ...

io_uring/timeout: fix multishot updates

After update only the first shot of a multishot timeout request adheres
to the new timeout value while all subsequent retries continue to use
the old value. D

io_uring/timeout: fix multishot updates

After update only the first shot of a multishot timeout request adheres
to the new timeout value while all subsequent retries continue to use
the old value. Don't forget to update the timeout stored in struct
io_timeout_data.

Cc: stable@vger.kernel.org
Fixes: ea97f6c8558e8 ("io_uring: add support for multishot timeouts")
Reported-by: Christian Mazakas <christian.mazakas@gmail.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/e6516c3304eb654ec234cfa65c88a9579861e597.1736015288.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring/kbuf: use pre-committed buffer address for non-pollable file

For non-pollable files, buffer ring consumption will commit upfront.
This is fine, but io_ring_buffer_select() will return the a

io_uring/kbuf: use pre-committed buffer address for non-pollable file

For non-pollable files, buffer ring consumption will commit upfront.
This is fine, but io_ring_buffer_select() will return the address of the
buffer after having committed it. For incrementally consumed buffers,
this is incorrect as it will modify the buffer address.

Store the pre-committed value and return that. If that isn't done, then
the initial part of the buffer is not used and the application will
correctly assume the content arrived at the start of the userspace
buffer, but the kernel will have put it later in the buffer. Or it can
cause a spurious -EFAULT returned in the CQE, depending on the buffer
size. As bounds are suitably checked for doing the actual IO, no adverse
side effects are possible - it's just a data misplacement within the
existing buffer.

Reported-by: Gwendal Fernet <gwendalfernet@gmail.com>
Cc: stable@vger.kernel.org
Fixes: ae98dbf43d75 ("io_uring/kbuf: add support for incremental buffer consumption")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring/net: always initialize kmsg->msg.msg_inq upfront

syzbot reports that ->msg_inq may get used uinitialized from the
following path:

BUG: KMSAN: uninit-value in io_recv_buf_select io_uring/ne

io_uring/net: always initialize kmsg->msg.msg_inq upfront

syzbot reports that ->msg_inq may get used uinitialized from the
following path:

BUG: KMSAN: uninit-value in io_recv_buf_select io_uring/net.c:1094 [inline]
BUG: KMSAN: uninit-value in io_recv+0x930/0x1f90 io_uring/net.c:1158
io_recv_buf_select io_uring/net.c:1094 [inline]
io_recv+0x930/0x1f90 io_uring/net.c:1158
io_issue_sqe+0x420/0x2130 io_uring/io_uring.c:1740
io_queue_sqe io_uring/io_uring.c:1950 [inline]
io_req_task_submit+0xfa/0x1d0 io_uring/io_uring.c:1374
io_handle_tw_list+0x55f/0x5c0 io_uring/io_uring.c:1057
tctx_task_work_run+0x109/0x3e0 io_uring/io_uring.c:1121
tctx_task_work+0x6d/0xc0 io_uring/io_uring.c:1139
task_work_run+0x268/0x310 kernel/task_work.c:239
io_run_task_work+0x43a/0x4a0 io_uring/io_uring.h:343
io_cqring_wait io_uring/io_uring.c:2527 [inline]
__do_sys_io_uring_enter io_uring/io_uring.c:3439 [inline]
__se_sys_io_uring_enter+0x204f/0x4ce0 io_uring/io_uring.c:3330
__x64_sys_io_uring_enter+0x11f/0x1a0 io_uring/io_uring.c:3330
x64_sys_call+0xce5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:427
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

and it is correct, as it's never initialized upfront. Hence the first
submission can end up using it uninitialized, if the recv wasn't
successful and the networking stack didn't honor ->msg_get_inq being set
and filling in the output value of ->msg_inq as requested.

Set it to 0 upfront when it's allocated, just to silence this KMSAN
warning. There's no side effect of using it uninitialized, it'll just
potentially cause the next receive to use a recv value hint that's not
accurate.

Fixes: c6f32c7d9e09 ("io_uring/net: get rid of ->prep_async() for receive side")
Reported-by: syzbot+068ff190354d2f74892f@syzkaller.appspotmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring/timeout: flush timeouts outside of the timeout lock

syzbot reports that a recent fix causes nesting issues between the (now)
raw timeoutlock and the eventfd locking:

======================

io_uring/timeout: flush timeouts outside of the timeout lock

syzbot reports that a recent fix causes nesting issues between the (now)
raw timeoutlock and the eventfd locking:

=============================
[ BUG: Invalid wait context ]
6.13.0-rc4-00080-g9828a4c0901f #29 Not tainted
-----------------------------
kworker/u32:0/68094 is trying to lock:
ffff000014d7a520 (&ctx->wqh#2){..-.}-{3:3}, at: eventfd_signal_mask+0x64/0x180
other info that might help us debug this:
context-{5:5}
6 locks held by kworker/u32:0/68094:
#0: ffff0000c1d98148 ((wq_completion)iou_exit){+.+.}-{0:0}, at: process_one_work+0x4e8/0xfc0
#1: ffff80008d927c78 ((work_completion)(&ctx->exit_work)){+.+.}-{0:0}, at: process_one_work+0x53c/0xfc0
#2: ffff0000c59bc3d8 (&ctx->completion_lock){+.+.}-{3:3}, at: io_kill_timeouts+0x40/0x180
#3: ffff0000c59bc358 (&ctx->timeout_lock){-.-.}-{2:2}, at: io_kill_timeouts+0x48/0x180
#4: ffff800085127aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x8/0x38
#5: ffff800085127aa0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire+0x8/0x38
stack backtrace:
CPU: 7 UID: 0 PID: 68094 Comm: kworker/u32:0 Not tainted 6.13.0-rc4-00080-g9828a4c0901f #29
Hardware name: linux,dummy-virt (DT)
Workqueue: iou_exit io_ring_exit_work
Call trace:
show_stack+0x1c/0x30 (C)
__dump_stack+0x24/0x30
dump_stack_lvl+0x60/0x80
dump_stack+0x14/0x20
__lock_acquire+0x19f8/0x60c8
lock_acquire+0x1a4/0x540
_raw_spin_lock_irqsave+0x90/0xd0
eventfd_signal_mask+0x64/0x180
io_eventfd_signal+0x64/0x108
io_req_local_work_add+0x294/0x430
__io_req_task_work_add+0x1c0/0x270
io_kill_timeout+0x1f0/0x288
io_kill_timeouts+0xd4/0x180
io_uring_try_cancel_requests+0x2e8/0x388
io_ring_exit_work+0x150/0x550
process_one_work+0x5e8/0xfc0
worker_thread+0x7ec/0xc80
kthread+0x24c/0x300
ret_from_fork+0x10/0x20

because after the preempt-rt fix for the timeout lock nesting inside
the io-wq lock, we now have the eventfd spinlock nesting inside the
raw timeout spinlock.

Rather than play whack-a-mole with other nesting on the timeout lock,
split the deletion and killing of timeouts so queueing the task_work
for the timeout cancelations can get done outside of the timeout lock.

Reported-by: syzbot+b1fc199a40b65d601b65@syzkaller.appspotmail.com
Fixes: 020b40f35624 ("io_uring: make ctx->timeout_lock a raw spinlock")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring/rw: fix downgraded mshot read

The io-wq path can downgrade a multishot request to oneshot mode,
however io_read_mshot() doesn't handle that and would still post
multiple CQEs. That's not al

io_uring/rw: fix downgraded mshot read

The io-wq path can downgrade a multishot request to oneshot mode,
however io_read_mshot() doesn't handle that and would still post
multiple CQEs. That's not allowed, because io_req_post_cqe() requires
stricter context requirements.

The described can only happen with pollable files that don't support
FMODE_NOWAIT, which is an odd combination, so if even allowed it should
be fairly rare.

Cc: stable@vger.kernel.org
Reported-by: chase xd <sl1589472800@gmail.com>
Fixes: bee1d5becdf5b ("io_uring: disable io-wq execution of multishot NOWAIT requests")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c5c8c4a50a882fd581257b81bf52eee260ac29fd.1735407848.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

show more ...

io_uring/sqpoll: fix sqpoll error handling races

BUG: KASAN: slab-use-after-free in __lock_acquire+0x370b/0x4a10 kernel/locking/lockdep.c:5089
Call Trace:
<TASK>
...
_raw_spin_lock_irqsave+0x3d/0x60

io_uring/sqpoll: fix sqpoll error handling races

BUG: KASAN: slab-use-after-free in __lock_acquire+0x370b/0x4a10 kernel/locking/lockdep.c:5089
Call Trace:
<TASK>
...
_raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162
class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:551 [inline]
try_to_wake_up+0xb5/0x23c0 kernel/sched/core.c:4205
io_sq_thread_park+0xac/0xe0 io_uring/sqpoll.c:55
io_sq_thread_finish+0x6b/0x310 io_uring/sqpoll.c:96
io_sq_offload_create+0x162/0x11d0 io_uring/sqpoll.c:497
io_uring_create io_uring/io_uring.c:3724 [inline]
io_uring_setup+0x1728/0x3230 io_uring/io_uring.c:3806
...

Kun Hu reports that the SQPOLL creating error path has UAF, which
happens if io_uring_alloc_task_context() fails and then io_sq_thread()
manages to run and complete before the rest of error handling code,
which means io_sq_thread_finish() is looking at already killed task.

Note that this is mostly theoretical, requiring fault injection on
the allocation side to trigger in practice.

Cc: stable@vger.kernel.org
Reported-by: Kun Hu <huk23@m.fudan.edu.cn>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/0f2f1aa5729332612bd01fe0f2f385fd1f06ce7c.1735231717.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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io_uring: check if iowq is killed before queuing

task work can be executed after the task has gone through io_uring
termination, whether it's the final task_work run or the fallback path.
In this ca

io_uring: check if iowq is killed before queuing

task work can be executed after the task has gone through io_uring
termination, whether it's the final task_work run or the fallback path.
In this case, task work will find ->io_wq being already killed and
null'ed, which is a problem if it then tries to forward the request to
io_queue_iowq(). Make io_queue_iowq() fail requests in this case.

Note that it also checks PF_KTHREAD, because the user can first close
a DEFER_TASKRUN ring and shortly after kill the task, in which case
->iowq check would race.

Cc: stable@vger.kernel.org
Fixes: 50c52250e2d74 ("block: implement async io_uring discard cmd")
Fixes: 773af69121ecc ("io_uring: always reissue from task_work context")
Reported-by: Will <willsroot@protonmail.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/63312b4a2c2bb67ad67b857d17a300e1d3b078e8.1734637909.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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io_uring/register: limit ring resizing to DEFER_TASKRUN

With DEFER_TASKRUN, we know the ring can't be both waited upon and
resized at the same time. This is important for CQ resizing. Allowing SQ
ri

io_uring/register: limit ring resizing to DEFER_TASKRUN

With DEFER_TASKRUN, we know the ring can't be both waited upon and
resized at the same time. This is important for CQ resizing. Allowing SQ
ring resizing is more trivial, but isn't the interesting use case. Hence
limit ring resizing in general to DEFER_TASKRUN only for now. This isn't
a huge problem as CQ ring resizing is generally the most useful on
networking type of workloads where it can be hard to size the ring
appropriately upfront, and those should be using DEFER_TASKRUN for
better performance.

Fixes: 79cfe9e59c2a ("io_uring/register: add IORING_REGISTER_RESIZE_RINGS")
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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io_uring: Fix registered ring file refcount leak

Currently, io_uring_unreg_ringfd() (which cleans up registered rings) is
only called on exit, but __io_uring_free (which frees the tctx in which the

io_uring: Fix registered ring file refcount leak

Currently, io_uring_unreg_ringfd() (which cleans up registered rings) is
only called on exit, but __io_uring_free (which frees the tctx in which the
registered ring pointers are stored) is also called on execve (via
begin_new_exec -> io_uring_task_cancel -> __io_uring_cancel ->
io_uring_cancel_generic -> __io_uring_free).

This means: A process going through execve while having registered rings
will leak references to the rings' `struct file`.

Fix it by zapping registered rings on execve(). This is implemented by
moving the io_uring_unreg_ringfd() from io_uring_files_cancel() into its
callee __io_uring_cancel(), which is called from io_uring_task_cancel() on
execve.

This could probably be exploited *on 32-bit kernels* by leaking 2^32
references to the same ring, because the file refcount is stored in a
pointer-sized field and get_file() doesn't have protection against
refcount overflow, just a WARN_ONCE(); but on 64-bit it should have no
impact beyond a memory leak.

Cc: stable@vger.kernel.org
Fixes: e7a6c00dc77a ("io_uring: add support for registering ring file descriptors")
Signed-off-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20241218-uring-reg-ring-cleanup-v1-1-8f63e999045b@google.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

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