ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 354 insertions, 0 deletions

diff --git a/net/sctp/chunk.c b/net/sctp/chunk.c
new file mode 100644
index 000000000..5b889e89e
--- /dev/null
+++ b/net/sctp/chunk.c
@@ -0,0 +1,354 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* SCTP kernel implementation
+ * (C) Copyright IBM Corp. 2003, 2004
+ *
+ * This file is part of the SCTP kernel implementation
+ *
+ * This file contains the code relating the chunk abstraction.
+ *
+ * Please send any bug reports or fixes you make to the
+ * email address(es):
+ *    lksctp developers <linux-sctp@vger.kernel.org>
+ *
+ * Written or modified by:
+ *    Jon Grimm             <jgrimm@us.ibm.com>
+ *    Sridhar Samudrala     <sri@us.ibm.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/net.h>
+#include <linux/inet.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <net/sock.h>
+#include <net/sctp/sctp.h>
+#include <net/sctp/sm.h>
+
+/* This file is mostly in anticipation of future work, but initially
+ * populate with fragment tracking for an outbound message.
+ */
+
+/* Initialize datamsg from memory. */
+static void sctp_datamsg_init(struct sctp_datamsg *msg)
+{
+	refcount_set(&msg->refcnt, 1);
+	msg->send_failed = 0;
+	msg->send_error = 0;
+	msg->can_delay = 1;
+	msg->abandoned = 0;
+	msg->expires_at = 0;
+	INIT_LIST_HEAD(&msg->chunks);
+}
+
+/* Allocate and initialize datamsg. */
+static struct sctp_datamsg *sctp_datamsg_new(gfp_t gfp)
+{
+	struct sctp_datamsg *msg;
+	msg = kmalloc_obj(struct sctp_datamsg, gfp);
+	if (msg) {
+		sctp_datamsg_init(msg);
+		SCTP_DBG_OBJCNT_INC(datamsg);
+	}
+	return msg;
+}
+
+void sctp_datamsg_free(struct sctp_datamsg *msg)
+{
+	struct sctp_chunk *chunk;
+
+	/* This doesn't have to be a _safe vairant because
+	 * sctp_chunk_free() only drops the refs.
+	 */
+	list_for_each_entry(chunk, &msg->chunks, frag_list)
+		sctp_chunk_free(chunk);
+
+	sctp_datamsg_put(msg);
+}
+
+/* Final destructruction of datamsg memory. */
+static void sctp_datamsg_destroy(struct sctp_datamsg *msg)
+{
+	struct sctp_association *asoc = NULL;
+	struct list_head *pos, *temp;
+	struct sctp_chunk *chunk;
+	struct sctp_ulpevent *ev;
+	int error, sent;
+
+	/* Release all references. */
+	list_for_each_safe(pos, temp, &msg->chunks) {
+		list_del_init(pos);
+		chunk = list_entry(pos, struct sctp_chunk, frag_list);
+
+		if (!msg->send_failed) {
+			sctp_chunk_put(chunk);
+			continue;
+		}
+
+		asoc = chunk->asoc;
+		error = msg->send_error ?: asoc->outqueue.error;
+		sent = chunk->has_tsn ? SCTP_DATA_SENT : SCTP_DATA_UNSENT;
+
+		if (sctp_ulpevent_type_enabled(asoc->subscribe,
+					       SCTP_SEND_FAILED)) {
+			ev = sctp_ulpevent_make_send_failed(asoc, chunk, sent,
+							    error, GFP_ATOMIC);
+			if (ev)
+				asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
+		}
+
+		if (sctp_ulpevent_type_enabled(asoc->subscribe,
+					       SCTP_SEND_FAILED_EVENT)) {
+			ev = sctp_ulpevent_make_send_failed_event(asoc, chunk,
+								  sent, error,
+								  GFP_ATOMIC);
+			if (ev)
+				asoc->stream.si->enqueue_event(&asoc->ulpq, ev);
+		}
+
+		sctp_chunk_put(chunk);
+	}
+
+	SCTP_DBG_OBJCNT_DEC(datamsg);
+	kfree(msg);
+}
+
+/* Hold a reference. */
+static void sctp_datamsg_hold(struct sctp_datamsg *msg)
+{
+	refcount_inc(&msg->refcnt);
+}
+
+/* Release a reference. */
+void sctp_datamsg_put(struct sctp_datamsg *msg)
+{
+	if (refcount_dec_and_test(&msg->refcnt))
+		sctp_datamsg_destroy(msg);
+}
+
+/* Assign a chunk to this datamsg. */
+static void sctp_datamsg_assign(struct sctp_datamsg *msg, struct sctp_chunk *chunk)
+{
+	sctp_datamsg_hold(msg);
+	chunk->msg = msg;
+}
+
+
+/* A data chunk can have a maximum payload of (2^16 - 20).  Break
+ * down any such message into smaller chunks.  Opportunistically, fragment
+ * the chunks down to the current MTU constraints.  We may get refragmented
+ * later if the PMTU changes, but it is _much better_ to fragment immediately
+ * with a reasonable guess than always doing our fragmentation on the
+ * soft-interrupt.
+ */
+struct sctp_datamsg *sctp_datamsg_from_user(struct sctp_association *asoc,
+					    struct sctp_sndrcvinfo *sinfo,
+					    struct iov_iter *from)
+{
+	size_t len, first_len, max_data, remaining;
+	size_t msg_len = iov_iter_count(from);
+	struct sctp_shared_key *shkey = NULL;
+	struct list_head *pos, *temp;
+	struct sctp_chunk *chunk;
+	struct sctp_datamsg *msg;
+	int err;
+
+	msg = sctp_datamsg_new(GFP_KERNEL);
+	if (!msg)
+		return ERR_PTR(-ENOMEM);
+
+	/* Note: Calculate this outside of the loop, so that all fragments
+	 * have the same expiration.
+	 */
+	if (asoc->peer.prsctp_capable && sinfo->sinfo_timetolive &&
+	    (SCTP_PR_TTL_ENABLED(sinfo->sinfo_flags) ||
+	     !SCTP_PR_POLICY(sinfo->sinfo_flags)))
+		msg->expires_at = jiffies +
+				  msecs_to_jiffies(sinfo->sinfo_timetolive);
+
+	/* This is the biggest possible DATA chunk that can fit into
+	 * the packet
+	 */
+	max_data = asoc->frag_point;
+	if (unlikely(!max_data)) {
+		max_data = sctp_min_frag_point(sctp_sk(asoc->base.sk),
+					       sctp_datachk_len(&asoc->stream));
+		pr_warn_ratelimited("%s: asoc:%p frag_point is zero, forcing max_data to default minimum (%zu)",
+				    __func__, asoc, max_data);
+	}
+
+	/* If the peer requested that we authenticate DATA chunks
+	 * we need to account for bundling of the AUTH chunks along with
+	 * DATA.
+	 */
+	if (sctp_auth_send_cid(SCTP_CID_DATA, asoc)) {
+		const struct sctp_hmac *hmac_desc =
+			sctp_auth_asoc_get_hmac(asoc);
+
+		if (hmac_desc)
+			max_data -= SCTP_PAD4(sizeof(struct sctp_auth_chunk) +
+					      hmac_desc->hmac_len);
+
+		if (sinfo->sinfo_tsn &&
+		    sinfo->sinfo_ssn != asoc->active_key_id) {
+			shkey = sctp_auth_get_shkey(asoc, sinfo->sinfo_ssn);
+			if (!shkey) {
+				err = -EINVAL;
+				goto errout;
+			}
+		} else {
+			shkey = asoc->shkey;
+		}
+	}
+
+	/* Set first_len and then account for possible bundles on first frag */
+	first_len = max_data;
+
+	/* Check to see if we have a pending SACK and try to let it be bundled
+	 * with this message.  Do this if we don't have any data queued already.
+	 * To check that, look at out_qlen and retransmit list.
+	 * NOTE: we will not reduce to account for SACK, if the message would
+	 * not have been fragmented.
+	 */
+	if (timer_pending(&asoc->timers[SCTP_EVENT_TIMEOUT_SACK]) &&
+	    asoc->outqueue.out_qlen == 0 &&
+	    list_empty(&asoc->outqueue.retransmit) &&
+	    msg_len > max_data)
+		first_len -= SCTP_PAD4(sizeof(struct sctp_sack_chunk));
+
+	/* Encourage Cookie-ECHO bundling. */
+	if (asoc->state < SCTP_STATE_COOKIE_ECHOED)
+		first_len -= SCTP_ARBITRARY_COOKIE_ECHO_LEN;
+
+	/* Account for a different sized first fragment */
+	if (msg_len >= first_len) {
+		msg->can_delay = 0;
+		if (msg_len > first_len)
+			SCTP_INC_STATS(asoc->base.net,
+				       SCTP_MIB_FRAGUSRMSGS);
+	} else {
+		/* Which may be the only one... */
+		first_len = msg_len;
+	}
+
+	/* Create chunks for all DATA chunks. */
+	for (remaining = msg_len; remaining; remaining -= len) {
+		u8 frag = SCTP_DATA_MIDDLE_FRAG;
+
+		if (remaining == msg_len) {
+			/* First frag, which may also be the last */
+			frag |= SCTP_DATA_FIRST_FRAG;
+			len = first_len;
+		} else {
+			/* Middle frags */
+			len = max_data;
+		}
+
+		if (len >= remaining) {
+			/* Last frag, which may also be the first */
+			len = remaining;
+			frag |= SCTP_DATA_LAST_FRAG;
+
+			/* The application requests to set the I-bit of the
+			 * last DATA chunk of a user message when providing
+			 * the user message to the SCTP implementation.
+			 */
+			if ((sinfo->sinfo_flags & SCTP_EOF) ||
+			    (sinfo->sinfo_flags & SCTP_SACK_IMMEDIATELY))
+				frag |= SCTP_DATA_SACK_IMM;
+		}
+
+		chunk = asoc->stream.si->make_datafrag(asoc, sinfo, len, frag,
+						       GFP_KERNEL);
+		if (!chunk) {
+			err = -ENOMEM;
+			goto errout;
+		}
+
+		err = sctp_user_addto_chunk(chunk, len, from);
+		if (err < 0)
+			goto errout_chunk_free;
+
+		chunk->shkey = shkey;
+
+		/* Put the chunk->skb back into the form expected by send.  */
+		__skb_pull(chunk->skb, (__u8 *)chunk->chunk_hdr -
+				       chunk->skb->data);
+
+		sctp_datamsg_assign(msg, chunk);
+		list_add_tail(&chunk->frag_list, &msg->chunks);
+	}
+
+	return msg;
+
+errout_chunk_free:
+	sctp_chunk_free(chunk);
+
+errout:
+	list_for_each_safe(pos, temp, &msg->chunks) {
+		list_del_init(pos);
+		chunk = list_entry(pos, struct sctp_chunk, frag_list);
+		sctp_chunk_free(chunk);
+	}
+	sctp_datamsg_put(msg);
+
+	return ERR_PTR(err);
+}
+
+/* Check whether this message has expired. */
+int sctp_chunk_abandoned(struct sctp_chunk *chunk)
+{
+	if (!chunk->asoc->peer.prsctp_capable)
+		return 0;
+
+	if (chunk->msg->abandoned)
+		return 1;
+
+	if (!chunk->has_tsn &&
+	    !(chunk->chunk_hdr->flags & SCTP_DATA_FIRST_FRAG))
+		return 0;
+
+	if (SCTP_PR_TTL_ENABLED(chunk->sinfo.sinfo_flags) &&
+	    time_after(jiffies, chunk->msg->expires_at)) {
+		struct sctp_stream_out *streamout =
+			SCTP_SO(&chunk->asoc->stream,
+				chunk->sinfo.sinfo_stream);
+
+		if (chunk->sent_count) {
+			chunk->asoc->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
+			streamout->ext->abandoned_sent[SCTP_PR_INDEX(TTL)]++;
+		} else {
+			chunk->asoc->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
+			streamout->ext->abandoned_unsent[SCTP_PR_INDEX(TTL)]++;
+		}
+		chunk->msg->abandoned = 1;
+		return 1;
+	} else if (SCTP_PR_RTX_ENABLED(chunk->sinfo.sinfo_flags) &&
+		   chunk->sent_count > chunk->sinfo.sinfo_timetolive) {
+		struct sctp_stream_out *streamout =
+			SCTP_SO(&chunk->asoc->stream,
+				chunk->sinfo.sinfo_stream);
+
+		chunk->asoc->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
+		streamout->ext->abandoned_sent[SCTP_PR_INDEX(RTX)]++;
+		chunk->msg->abandoned = 1;
+		return 1;
+	} else if (!SCTP_PR_POLICY(chunk->sinfo.sinfo_flags) &&
+		   chunk->msg->expires_at &&
+		   time_after(jiffies, chunk->msg->expires_at)) {
+		chunk->msg->abandoned = 1;
+		return 1;
+	}
+	/* PRIO policy is processed by sendmsg, not here */
+
+	return 0;
+}
+
+/* This chunk (and consequently entire message) has failed in its sending. */
+void sctp_chunk_fail(struct sctp_chunk *chunk, int error)
+{
+	chunk->msg->send_failed = 1;
+	chunk->msg->send_error = error;
+}