x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

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 ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 755 insertions, 0 deletions

diff --git a/io_uring/timeout.c b/io_uring/timeout.c
new file mode 100644
index 000000000..c4dd26cf3
--- /dev/null
+++ b/io_uring/timeout.c
@@ -0,0 +1,755 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/file.h>
+#include <linux/io_uring.h>
+#include <linux/time_namespace.h>
+
+#include <trace/events/io_uring.h>
+
+#include <uapi/linux/io_uring.h>
+
+#include "io_uring.h"
+#include "refs.h"
+#include "cancel.h"
+#include "timeout.h"
+
+struct io_timeout {
+	struct file			*file;
+	u32				off;
+	u32				target_seq;
+	u32				repeats;
+	struct list_head		list;
+	/* head of the link, used by linked timeouts only */
+	struct io_kiocb			*head;
+	/* for linked completions */
+	struct io_kiocb			*prev;
+};
+
+struct io_timeout_rem {
+	struct file			*file;
+	u64				addr;
+
+	/* timeout update */
+	ktime_t				time;
+	u32				flags;
+	bool				ltimeout;
+};
+
+static clockid_t io_flags_to_clock(unsigned flags)
+{
+	switch (flags & IORING_TIMEOUT_CLOCK_MASK) {
+	case IORING_TIMEOUT_BOOTTIME:
+		return CLOCK_BOOTTIME;
+	case IORING_TIMEOUT_REALTIME:
+		return CLOCK_REALTIME;
+	default:
+		/* can't happen, vetted at prep time */
+		WARN_ON_ONCE(1);
+		fallthrough;
+	case 0:
+		return CLOCK_MONOTONIC;
+	}
+}
+
+static int io_parse_user_time(ktime_t *time, u64 arg, unsigned flags)
+{
+	struct timespec64 ts;
+
+	if (flags & IORING_TIMEOUT_IMMEDIATE_ARG) {
+		*time = ns_to_ktime(arg);
+		if (*time < 0)
+			return -EINVAL;
+		goto out;
+	}
+
+	if (get_timespec64(&ts, u64_to_user_ptr(arg)))
+		return -EFAULT;
+	if (ts.tv_sec < 0 || ts.tv_nsec < 0)
+		return -EINVAL;
+	*time = timespec64_to_ktime(ts);
+out:
+	if (flags & IORING_TIMEOUT_ABS)
+		*time = timens_ktime_to_host(io_flags_to_clock(flags), *time);
+	return 0;
+}
+
+static struct io_kiocb *__io_disarm_linked_timeout(struct io_kiocb *req,
+						   struct io_kiocb *link);
+
+static inline bool io_is_timeout_noseq(struct io_kiocb *req)
+{
+	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
+	struct io_timeout_data *data = req->async_data;
+
+	return !timeout->off || data->flags & IORING_TIMEOUT_MULTISHOT;
+}
+
+static inline void io_put_req(struct io_kiocb *req)
+{
+	if (req_ref_put_and_test(req)) {
+		io_queue_next(req);
+		io_free_req(req);
+	}
+}
+
+static inline bool io_timeout_finish(struct io_timeout *timeout,
+				     struct io_timeout_data *data)
+{
+	if (!(data->flags & IORING_TIMEOUT_MULTISHOT))
+		return true;
+
+	if (!timeout->off || (timeout->repeats && --timeout->repeats))
+		return false;
+
+	return true;
+}
+
+static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer);
+
+static void io_timeout_complete(struct io_tw_req tw_req, io_tw_token_t tw)
+{
+	struct io_kiocb *req = tw_req.req;
+	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
+	struct io_timeout_data *data = req->async_data;
+	struct io_ring_ctx *ctx = req->ctx;
+
+	if (!io_timeout_finish(timeout, data)) {
+		if (io_req_post_cqe(req, -ETIME, IORING_CQE_F_MORE)) {
+			/* re-arm timer */
+			raw_spin_lock_irq(&ctx->timeout_lock);
+			list_add(&timeout->list, ctx->timeout_list.prev);
+			hrtimer_start(&data->timer, data->time, data->mode);
+			raw_spin_unlock_irq(&ctx->timeout_lock);
+			return;
+		}
+	}
+
+	io_req_task_complete(tw_req, tw);
+}
+
+static __cold bool io_flush_killed_timeouts(struct list_head *list, int err)
+{
+	if (list_empty(list))
+		return false;
+
+	while (!list_empty(list)) {
+		struct io_timeout *timeout;
+		struct io_kiocb *req;
+
+		timeout = list_first_entry(list, struct io_timeout, list);
+		list_del_init(&timeout->list);
+		req = cmd_to_io_kiocb(timeout);
+		if (err)
+			req_set_fail(req);
+		io_req_queue_tw_complete(req, err);
+	}
+
+	return true;
+}
+
+static void io_kill_timeout(struct io_kiocb *req, struct list_head *list)
+	__must_hold(&req->ctx->timeout_lock)
+{
+	struct io_timeout_data *io = req->async_data;
+
+	if (hrtimer_try_to_cancel(&io->timer) != -1) {
+		struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
+
+		atomic_set(&req->ctx->cq_timeouts,
+			atomic_read(&req->ctx->cq_timeouts) + 1);
+		list_move_tail(&timeout->list, list);
+	}
+}
+
+__cold void io_flush_timeouts(struct io_ring_ctx *ctx)
+{
+	struct io_timeout *timeout, *tmp;
+	LIST_HEAD(list);
+	u32 seq;
+
+	raw_spin_lock_irq(&ctx->timeout_lock);
+	seq = READ_ONCE(ctx->cached_cq_tail) - atomic_read(&ctx->cq_timeouts);
+
+	list_for_each_entry_safe(timeout, tmp, &ctx->timeout_list, list) {
+		struct io_kiocb *req = cmd_to_io_kiocb(timeout);
+		u32 events_needed, events_got;
+
+		if (io_is_timeout_noseq(req))
+			break;
+
+		/*
+		 * Since seq can easily wrap around over time, subtract
+		 * the last seq at which timeouts were flushed before comparing.
+		 * Assuming not more than 2^31-1 events have happened since,
+		 * these subtractions won't have wrapped, so we can check if
+		 * target is in [last_seq, current_seq] by comparing the two.
+		 */
+		events_needed = timeout->target_seq - ctx->cq_last_tm_flush;
+		events_got = seq - ctx->cq_last_tm_flush;
+		if (events_got < events_needed)
+			break;
+
+		io_kill_timeout(req, &list);
+	}
+	ctx->cq_last_tm_flush = seq;
+	raw_spin_unlock_irq(&ctx->timeout_lock);
+	io_flush_killed_timeouts(&list, 0);
+}
+
+static void io_req_tw_fail_links(struct io_tw_req tw_req, io_tw_token_t tw)
+{
+	struct io_kiocb *link = tw_req.req;
+
+	io_tw_lock(link->ctx, tw);
+	while (link) {
+		struct io_kiocb *nxt = link->link;
+		long res = -ECANCELED;
+
+		if (link->flags & REQ_F_FAIL)
+			res = link->cqe.res;
+		link->link = NULL;
+		io_req_set_res(link, res, 0);
+		io_req_task_complete((struct io_tw_req){link}, tw);
+		link = nxt;
+	}
+}
+
+static void io_fail_links(struct io_kiocb *req)
+	__must_hold(&req->ctx->completion_lock)
+{
+	struct io_kiocb *link = req->link;
+	bool ignore_cqes = req->flags & REQ_F_SKIP_LINK_CQES;
+
+	if (!link)
+		return;
+
+	while (link) {
+		if (ignore_cqes)
+			link->flags |= REQ_F_CQE_SKIP;
+		else
+			link->flags &= ~REQ_F_CQE_SKIP;
+		trace_io_uring_fail_link(req, link);
+		link = link->link;
+	}
+
+	link = req->link;
+	link->io_task_work.func = io_req_tw_fail_links;
+	io_req_task_work_add(link);
+	req->link = NULL;
+}
+
+static inline void io_remove_next_linked(struct io_kiocb *req)
+{
+	struct io_kiocb *nxt = req->link;
+
+	req->link = nxt->link;
+	nxt->link = NULL;
+}
+
+void io_disarm_next(struct io_kiocb *req)
+	__must_hold(&req->ctx->completion_lock)
+{
+	struct io_kiocb *link = NULL;
+
+	if (req->flags & REQ_F_ARM_LTIMEOUT) {
+		link = req->link;
+		req->flags &= ~REQ_F_ARM_LTIMEOUT;
+		if (link && link->opcode == IORING_OP_LINK_TIMEOUT) {
+			io_remove_next_linked(req);
+			io_req_queue_tw_complete(link, -ECANCELED);
+		}
+	} else if (req->flags & REQ_F_LINK_TIMEOUT) {
+		struct io_ring_ctx *ctx = req->ctx;
+
+		raw_spin_lock_irq(&ctx->timeout_lock);
+		if (req->link && req->link->opcode == IORING_OP_LINK_TIMEOUT)
+			link = __io_disarm_linked_timeout(req, req->link);
+
+		raw_spin_unlock_irq(&ctx->timeout_lock);
+		if (link)
+			io_req_queue_tw_complete(link, -ECANCELED);
+	}
+	if (unlikely((req->flags & REQ_F_FAIL) &&
+		     !(req->flags & REQ_F_HARDLINK)))
+		io_fail_links(req);
+}
+
+static struct io_kiocb *__io_disarm_linked_timeout(struct io_kiocb *req,
+						   struct io_kiocb *link)
+	__must_hold(&req->ctx->completion_lock)
+	__must_hold(&req->ctx->timeout_lock)
+{
+	struct io_timeout_data *io = link->async_data;
+	struct io_timeout *timeout = io_kiocb_to_cmd(link, struct io_timeout);
+
+	io_remove_next_linked(req);
+
+	/* If this is NULL, then timer already claimed it and will complete it */
+	if (!timeout->head)
+		return NULL;
+	timeout->head = NULL;
+	if (hrtimer_try_to_cancel(&io->timer) != -1) {
+		list_del(&timeout->list);
+		return link;
+	}
+
+	return NULL;
+}
+
+static enum hrtimer_restart io_timeout_fn(struct hrtimer *timer)
+{
+	struct io_timeout_data *data = container_of(timer,
+						struct io_timeout_data, timer);
+	struct io_kiocb *req = data->req;
+	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
+	struct io_ring_ctx *ctx = req->ctx;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&ctx->timeout_lock, flags);
+	list_del_init(&timeout->list);
+	atomic_set(&ctx->cq_timeouts,
+		atomic_read(&ctx->cq_timeouts) + 1);
+	raw_spin_unlock_irqrestore(&ctx->timeout_lock, flags);
+
+	if (!(data->flags & IORING_TIMEOUT_ETIME_SUCCESS))
+		req_set_fail(req);
+
+	io_req_set_res(req, -ETIME, 0);
+	req->io_task_work.func = io_timeout_complete;
+	io_req_task_work_add(req);
+	return HRTIMER_NORESTART;
+}
+
+static struct io_kiocb *io_timeout_extract(struct io_ring_ctx *ctx,
+					   struct io_cancel_data *cd)
+	__must_hold(&ctx->timeout_lock)
+{
+	struct io_timeout *timeout;
+	struct io_timeout_data *io;
+	struct io_kiocb *req = NULL;
+
+	list_for_each_entry(timeout, &ctx->timeout_list, list) {
+		struct io_kiocb *tmp = cmd_to_io_kiocb(timeout);
+
+		if (io_cancel_req_match(tmp, cd)) {
+			req = tmp;
+			break;
+		}
+	}
+	if (!req)
+		return ERR_PTR(-ENOENT);
+
+	io = req->async_data;
+	if (hrtimer_try_to_cancel(&io->timer) == -1)
+		return ERR_PTR(-EALREADY);
+	timeout = io_kiocb_to_cmd(req, struct io_timeout);
+	list_del_init(&timeout->list);
+	return req;
+}
+
+int io_timeout_cancel(struct io_ring_ctx *ctx, struct io_cancel_data *cd)
+	__must_hold(&ctx->completion_lock)
+{
+	struct io_kiocb *req;
+
+	raw_spin_lock_irq(&ctx->timeout_lock);
+	req = io_timeout_extract(ctx, cd);
+	raw_spin_unlock_irq(&ctx->timeout_lock);
+
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+	io_req_task_queue_fail(req, -ECANCELED);
+	return 0;
+}
+
+static void io_req_task_link_timeout(struct io_tw_req tw_req, io_tw_token_t tw)
+{
+	struct io_kiocb *req = tw_req.req;
+	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
+	struct io_kiocb *prev = timeout->prev;
+	int ret;
+
+	if (prev) {
+		/*
+		 * splice the linked timeout out of prev's chain if the regular
+		 * completion path didn't already do it.
+		 */
+		if (prev->link == req)
+			prev->link = req->link;
+		req->link = NULL;
+
+		if (!tw.cancel) {
+			struct io_cancel_data cd = {
+				.ctx		= req->ctx,
+				.data		= prev->cqe.user_data,
+			};
+
+			ret = io_try_cancel(req->tctx, &cd, 0);
+		} else {
+			ret = -ECANCELED;
+		}
+		io_req_set_res(req, ret ?: -ETIME, 0);
+		io_req_task_complete(tw_req, tw);
+		io_put_req(prev);
+	} else {
+		io_req_set_res(req, -ETIME, 0);
+		io_req_task_complete(tw_req, tw);
+	}
+}
+
+static enum hrtimer_restart io_link_timeout_fn(struct hrtimer *timer)
+{
+	struct io_timeout_data *data = container_of(timer,
+						struct io_timeout_data, timer);
+	struct io_kiocb *prev, *req = data->req;
+	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
+	struct io_ring_ctx *ctx = req->ctx;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&ctx->timeout_lock, flags);
+	prev = timeout->head;
+	timeout->head = NULL;
+
+	/*
+	 * We don't expect the list to be empty, that will only happen if we
+	 * race with the completion of the linked work. Splice of prev is
+	 * done in io_req_task_link_timeout(), if needed.
+	 */
+	if (prev) {
+		if (!req_ref_inc_not_zero(prev)) {
+			io_remove_next_linked(prev);
+			prev = NULL;
+		}
+	}
+	list_del(&timeout->list);
+	timeout->prev = prev;
+	raw_spin_unlock_irqrestore(&ctx->timeout_lock, flags);
+
+	req->io_task_work.func = io_req_task_link_timeout;
+	io_req_task_work_add(req);
+	return HRTIMER_NORESTART;
+}
+
+static clockid_t io_timeout_get_clock(struct io_timeout_data *data)
+{
+	return io_flags_to_clock(data->flags);
+}
+
+static int io_linked_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
+				    ktime_t ts, enum hrtimer_mode mode)
+	__must_hold(&ctx->timeout_lock)
+{
+	struct io_timeout_data *io;
+	struct io_timeout *timeout;
+	struct io_kiocb *req = NULL;
+
+	list_for_each_entry(timeout, &ctx->ltimeout_list, list) {
+		struct io_kiocb *tmp = cmd_to_io_kiocb(timeout);
+
+		if (user_data == tmp->cqe.user_data) {
+			req = tmp;
+			break;
+		}
+	}
+	if (!req)
+		return -ENOENT;
+
+	io = req->async_data;
+	if (hrtimer_try_to_cancel(&io->timer) == -1)
+		return -EALREADY;
+	hrtimer_setup(&io->timer, io_link_timeout_fn, io_timeout_get_clock(io), mode);
+	hrtimer_start(&io->timer, ts, mode);
+	return 0;
+}
+
+static int io_timeout_update(struct io_ring_ctx *ctx, __u64 user_data,
+			     ktime_t time, enum hrtimer_mode mode)
+	__must_hold(&ctx->timeout_lock)
+{
+	struct io_cancel_data cd = { .ctx = ctx, .data = user_data, };
+	struct io_kiocb *req = io_timeout_extract(ctx, &cd);
+	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
+	struct io_timeout_data *data;
+
+	if (IS_ERR(req))
+		return PTR_ERR(req);
+
+	timeout->off = 0; /* noseq */
+	data = req->async_data;
+	data->time = time;
+
+	list_add_tail(&timeout->list, &ctx->timeout_list);
+	hrtimer_setup(&data->timer, io_timeout_fn, io_timeout_get_clock(data), mode);
+	hrtimer_start(&data->timer, data->time, mode);
+	return 0;
+}
+
+int io_timeout_remove_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_timeout_rem *tr = io_kiocb_to_cmd(req, struct io_timeout_rem);
+	int ret;
+
+	if (unlikely(req->flags & (REQ_F_FIXED_FILE | REQ_F_BUFFER_SELECT)))
+		return -EINVAL;
+	if (sqe->addr3 || sqe->__pad2[0])
+		return -EINVAL;
+	if (sqe->buf_index || sqe->len || sqe->splice_fd_in)
+		return -EINVAL;
+
+	tr->ltimeout = false;
+	tr->addr = READ_ONCE(sqe->addr);
+	tr->flags = READ_ONCE(sqe->timeout_flags);
+	if (tr->flags & IORING_TIMEOUT_UPDATE_MASK) {
+		if (hweight32(tr->flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
+			return -EINVAL;
+		if (tr->flags & IORING_LINK_TIMEOUT_UPDATE)
+			tr->ltimeout = true;
+		if (tr->flags & ~(IORING_TIMEOUT_UPDATE_MASK |
+				  IORING_TIMEOUT_ABS |
+				  IORING_TIMEOUT_IMMEDIATE_ARG))
+			return -EINVAL;
+		ret = io_parse_user_time(&tr->time, READ_ONCE(sqe->addr2), tr->flags);
+		if (ret)
+			return ret;
+	} else if (tr->flags) {
+		/* timeout removal doesn't support flags */
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static inline enum hrtimer_mode io_translate_timeout_mode(unsigned int flags)
+{
+	return (flags & IORING_TIMEOUT_ABS) ? HRTIMER_MODE_ABS
+					    : HRTIMER_MODE_REL;
+}
+
+/*
+ * Remove or update an existing timeout command
+ */
+int io_timeout_remove(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_timeout_rem *tr = io_kiocb_to_cmd(req, struct io_timeout_rem);
+	struct io_ring_ctx *ctx = req->ctx;
+	int ret;
+
+	if (!(tr->flags & IORING_TIMEOUT_UPDATE)) {
+		struct io_cancel_data cd = { .ctx = ctx, .data = tr->addr, };
+
+		spin_lock(&ctx->completion_lock);
+		ret = io_timeout_cancel(ctx, &cd);
+		spin_unlock(&ctx->completion_lock);
+	} else {
+		enum hrtimer_mode mode = io_translate_timeout_mode(tr->flags);
+
+		raw_spin_lock_irq(&ctx->timeout_lock);
+		if (tr->ltimeout)
+			ret = io_linked_timeout_update(ctx, tr->addr, tr->time, mode);
+		else
+			ret = io_timeout_update(ctx, tr->addr, tr->time, mode);
+		raw_spin_unlock_irq(&ctx->timeout_lock);
+	}
+
+	if (ret < 0)
+		req_set_fail(req);
+	io_req_set_res(req, ret, 0);
+	return IOU_COMPLETE;
+}
+
+static int __io_timeout_prep(struct io_kiocb *req,
+			     const struct io_uring_sqe *sqe,
+			     bool is_timeout_link)
+{
+	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
+	struct io_timeout_data *data;
+	unsigned flags;
+	u32 off = READ_ONCE(sqe->off);
+	int ret;
+
+	if (sqe->addr3 || sqe->__pad2[0])
+		return -EINVAL;
+	if (sqe->buf_index || sqe->len != 1 || sqe->splice_fd_in)
+		return -EINVAL;
+	if (off && is_timeout_link)
+		return -EINVAL;
+	flags = READ_ONCE(sqe->timeout_flags);
+	if (flags & ~(IORING_TIMEOUT_ABS | IORING_TIMEOUT_CLOCK_MASK |
+		      IORING_TIMEOUT_ETIME_SUCCESS |
+		      IORING_TIMEOUT_MULTISHOT |
+		      IORING_TIMEOUT_IMMEDIATE_ARG))
+		return -EINVAL;
+	/* more than one clock specified is invalid, obviously */
+	if (hweight32(flags & IORING_TIMEOUT_CLOCK_MASK) > 1)
+		return -EINVAL;
+	/* multishot requests only make sense with rel values */
+	if (!(~flags & (IORING_TIMEOUT_MULTISHOT | IORING_TIMEOUT_ABS)))
+		return -EINVAL;
+
+	INIT_LIST_HEAD(&timeout->list);
+	timeout->off = off;
+	if (unlikely(off && !(req->ctx->int_flags & IO_RING_F_OFF_TIMEOUT_USED)))
+		req->ctx->int_flags |= IO_RING_F_OFF_TIMEOUT_USED;
+	/*
+	 * for multishot reqs w/ fixed nr of repeats, repeats tracks the
+	 * remaining nr
+	 */
+	timeout->repeats = 0;
+	if ((flags & IORING_TIMEOUT_MULTISHOT) && off > 0)
+		timeout->repeats = off;
+
+	if (WARN_ON_ONCE(req_has_async_data(req)))
+		return -EFAULT;
+	data = io_uring_alloc_async_data(NULL, req);
+	if (!data)
+		return -ENOMEM;
+	data->req = req;
+	data->flags = flags;
+
+	ret = io_parse_user_time(&data->time, READ_ONCE(sqe->addr), flags);
+	if (ret)
+		return ret;
+
+	data->mode = io_translate_timeout_mode(flags);
+
+	if (is_timeout_link) {
+		struct io_submit_link *link = &req->ctx->submit_state.link;
+
+		if (!link->head)
+			return -EINVAL;
+		if (link->last->opcode == IORING_OP_LINK_TIMEOUT)
+			return -EINVAL;
+		timeout->head = link->last;
+		link->last->flags |= REQ_F_ARM_LTIMEOUT;
+		hrtimer_setup(&data->timer, io_link_timeout_fn, io_timeout_get_clock(data),
+			      data->mode);
+	} else {
+		hrtimer_setup(&data->timer, io_timeout_fn, io_timeout_get_clock(data), data->mode);
+	}
+	return 0;
+}
+
+int io_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	return __io_timeout_prep(req, sqe, false);
+}
+
+int io_link_timeout_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	return __io_timeout_prep(req, sqe, true);
+}
+
+int io_timeout(struct io_kiocb *req, unsigned int issue_flags)
+{
+	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_timeout_data *data = req->async_data;
+	struct list_head *entry;
+	u32 tail, off = timeout->off;
+
+	raw_spin_lock_irq(&ctx->timeout_lock);
+
+	/*
+	 * sqe->off holds how many events that need to occur for this
+	 * timeout event to be satisfied. If it isn't set, then this is
+	 * a pure timeout request, sequence isn't used.
+	 */
+	if (io_is_timeout_noseq(req)) {
+		entry = ctx->timeout_list.prev;
+		goto add;
+	}
+
+	tail = data_race(ctx->cached_cq_tail) - atomic_read(&ctx->cq_timeouts);
+	timeout->target_seq = tail + off;
+
+	/* Update the last seq here in case io_flush_timeouts() hasn't.
+	 * This is safe because ->completion_lock is held, and submissions
+	 * and completions are never mixed in the same ->completion_lock section.
+	 */
+	ctx->cq_last_tm_flush = tail;
+
+	/*
+	 * Insertion sort, ensuring the first entry in the list is always
+	 * the one we need first.
+	 */
+	list_for_each_prev(entry, &ctx->timeout_list) {
+		struct io_timeout *nextt = list_entry(entry, struct io_timeout, list);
+		struct io_kiocb *nxt = cmd_to_io_kiocb(nextt);
+
+		if (io_is_timeout_noseq(nxt))
+			continue;
+		/* nxt.seq is behind @tail, otherwise would've been completed */
+		if (off >= nextt->target_seq - tail)
+			break;
+	}
+add:
+	list_add(&timeout->list, entry);
+	hrtimer_start(&data->timer, data->time, data->mode);
+	raw_spin_unlock_irq(&ctx->timeout_lock);
+	return IOU_ISSUE_SKIP_COMPLETE;
+}
+
+void io_queue_linked_timeout(struct io_kiocb *req)
+{
+	struct io_timeout *timeout = io_kiocb_to_cmd(req, struct io_timeout);
+	struct io_ring_ctx *ctx = req->ctx;
+
+	raw_spin_lock_irq(&ctx->timeout_lock);
+	/*
+	 * If the back reference is NULL, then our linked request finished
+	 * before we got a chance to setup the timer
+	 */
+	if (timeout->head) {
+		struct io_timeout_data *data = req->async_data;
+
+		hrtimer_start(&data->timer, data->time, data->mode);
+		list_add_tail(&timeout->list, &ctx->ltimeout_list);
+	}
+	raw_spin_unlock_irq(&ctx->timeout_lock);
+	/* drop submission reference */
+	io_put_req(req);
+}
+
+static bool io_match_task(struct io_kiocb *head, struct io_uring_task *tctx,
+			  bool cancel_all)
+	__must_hold(&head->ctx->timeout_lock)
+{
+	struct io_kiocb *req;
+
+	if (tctx && head->tctx != tctx)
+		return false;
+	if (cancel_all)
+		return true;
+
+	io_for_each_link(req, head) {
+		if (req->flags & REQ_F_INFLIGHT)
+			return true;
+	}
+	return false;
+}
+
+/* Returns true if we found and killed one or more timeouts */
+__cold bool io_kill_timeouts(struct io_ring_ctx *ctx, struct io_uring_task *tctx,
+			     bool cancel_all)
+{
+	struct io_timeout *timeout, *tmp;
+	LIST_HEAD(list);
+
+	/*
+	 * completion_lock is needed for io_match_task(). Take it before
+	 * timeout_lockfirst to keep locking ordering.
+	 */
+	spin_lock(&ctx->completion_lock);
+	raw_spin_lock_irq(&ctx->timeout_lock);
+	list_for_each_entry_safe(timeout, tmp, &ctx->timeout_list, list) {
+		struct io_kiocb *req = cmd_to_io_kiocb(timeout);
+
+		if (io_match_task(req, tctx, cancel_all))
+			io_kill_timeout(req, &list);
+	}
+	raw_spin_unlock_irq(&ctx->timeout_lock);
+	spin_unlock(&ctx->completion_lock);
+
+	return io_flush_killed_timeouts(&list, -ECANCELED);
+}