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, 175 insertions, 0 deletions

diff --git a/net/mac80211/tests/ttlm.c b/net/mac80211/tests/ttlm.c
new file mode 100644
index 000000000..18d0592b1
--- /dev/null
+++ b/net/mac80211/tests/ttlm.c
@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * KUnit tests for negotiated TTLM (TID-To-Link Mapping) parsing
+ *
+ * Copyright (C) 2026 Michael Bommarito <michael.bommarito@gmail.com>
+ */
+#include <kunit/test.h>
+#include <linux/ieee80211.h>
+#include "../ieee80211_i.h"
+
+MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");
+
+/*
+ * Build a negotiated TTLM element in caller-supplied buffer.
+ *
+ * @buf:       destination buffer (must be at least elem_size bytes)
+ * @elem_size: sizeof(ttlm_elem) + 1 (presence byte) + npresent * bm_size
+ * @presence:  link_map_presence bitmask; each set bit => one map follows
+ * @bm_size:   bytes per map (1 or 2); 2 => LINK_MAP_SIZE bit clear
+ * @maps:      array of npresent u16 maps, one per set bit in presence
+ *
+ * Control field encodes direction=BOTH; no switch-time, no expected-dur,
+ * no DEF_LINK_MAP.  LINK_MAP_SIZE bit is set iff bm_size==1.
+ *
+ * Returns pointer to the ieee80211_ttlm_elem at buf.
+ */
+static const struct ieee80211_ttlm_elem *
+build_neg_ttlm_elem(u8 *buf, size_t elem_size,
+		    u8 presence, u8 bm_size, const u16 *maps)
+{
+	struct ieee80211_ttlm_elem *t = (void *)buf;
+	u8 control;
+	u8 *pos;
+	int i, tid;
+
+	memset(buf, 0, elem_size);
+
+	control = IEEE80211_TTLM_DIRECTION_BOTH; /* bits [1:0] = 2 */
+	if (bm_size == 1)
+		control |= IEEE80211_TTLM_CONTROL_LINK_MAP_SIZE;
+
+	t->control = control;
+
+	pos = (u8 *)t->optional;
+	*pos++ = presence;
+
+	i = 0;
+	for (tid = 0; tid < IEEE80211_TTLM_NUM_TIDS; tid++) {
+		if (!(presence & BIT(tid)))
+			continue;
+		if (bm_size == 1)
+			*pos = (u8)maps[i];
+		else
+			put_unaligned_le16(maps[i], pos);
+		pos += bm_size;
+		i++;
+	}
+
+	return t;
+}
+
+/*
+ * sparse_presence_no_oob_read - BIT(0)|BIT(7) presence, bm_size=2
+ *
+ * Only TID 0 and TID 7 have maps; TIDs 1-6 are absent.  Element length
+ * is exactly 6 bytes (1 control + 1 presence + 2 * 2-byte maps).
+ *
+ * Pre-fix the parser advanced pos by bm_size AFTER the switch() block
+ * (i.e. unconditionally for every TID), so when processing TID 7 it
+ * had already advanced 6 * bm_size = 12 bytes past the presence byte
+ * for the absent TIDs before reading the TID-7 map - 14 bytes past the
+ * end of the 2-byte TID-7 map.  Under KASAN that is a slab-out-of-bounds.
+ *
+ * After the fix pos is advanced only inside the presence-bit branch so
+ * the cursor lands exactly at end-of-element after processing TID 7.
+ */
+static void sparse_presence_no_oob_read(struct kunit *test)
+{
+	/*
+	 * presence = BIT(0)|BIT(7): 2 maps present.
+	 * elem_size = sizeof(ttlm_elem) + 1 (presence) + 2*2 (maps) = 6.
+	 */
+	const u8 presence = BIT(0) | BIT(7);
+	const u8 bm_size = 2;
+	const int npresent = 2;
+	const size_t elem_size = sizeof(struct ieee80211_ttlm_elem)
+				 + 1 + npresent * bm_size;
+	/*
+	 * Allocate exact-size buffer so a pre-fix OOB read walks into the
+	 * KASAN red zone immediately after the allocation.
+	 */
+	u8 *buf = kunit_kzalloc(test, elem_size, GFP_KERNEL);
+	const struct ieee80211_ttlm_elem *ttlm;
+	struct ieee80211_neg_ttlm neg_ttlm = {};
+	/* Non-zero maps so the parser does not reject with -EINVAL. */
+	const u16 maps[2] = { 0x0001, 0x0001 };
+	u8 direction = 0;
+	int ret;
+
+	KUNIT_ASSERT_NOT_NULL(test, buf);
+
+	ttlm = build_neg_ttlm_elem(buf, elem_size, presence, bm_size, maps);
+
+	/*
+	 * Pass NULL for sdata: the only sdata dereference in this code path
+	 * is inside mlme_dbg() on error returns, which are guarded by
+	 * MAC80211_MLME_DEBUG == 0 in non-debug builds and by the dead-code
+	 * eliminator in KUnit builds.  The success path does not touch sdata.
+	 */
+	ret = ieee80211_parse_neg_ttlm(NULL, ttlm, &neg_ttlm, &direction);
+
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, (int)direction, IEEE80211_TTLM_DIRECTION_BOTH);
+	/* TID 0: map present */
+	KUNIT_EXPECT_EQ(test, (int)neg_ttlm.downlink[0], 0x0001);
+	KUNIT_EXPECT_EQ(test, (int)neg_ttlm.uplink[0],   0x0001);
+	/* TID 3: absent => map should be 0 */
+	KUNIT_EXPECT_EQ(test, (int)neg_ttlm.downlink[3], 0);
+	KUNIT_EXPECT_EQ(test, (int)neg_ttlm.uplink[3],   0);
+	/* TID 7: map present */
+	KUNIT_EXPECT_EQ(test, (int)neg_ttlm.downlink[7], 0x0001);
+	KUNIT_EXPECT_EQ(test, (int)neg_ttlm.uplink[7],   0x0001);
+}
+
+/*
+ * dense_presence_baseline - presence=0xff (all 8 TIDs), bm_size=2
+ *
+ * Every TID has a map; this is the dense layout the parser handled
+ * correctly even before the fix.  Confirms the cursor-advance fix
+ * does not regress the already-correct path.
+ */
+static void dense_presence_baseline(struct kunit *test)
+{
+	const u8 presence = 0xff;
+	const u8 bm_size = 2;
+	const int npresent = 8;
+	const size_t elem_size = sizeof(struct ieee80211_ttlm_elem)
+				 + 1 + npresent * bm_size;
+	u8 *buf = kunit_kzalloc(test, elem_size, GFP_KERNEL);
+	const struct ieee80211_ttlm_elem *ttlm;
+	struct ieee80211_neg_ttlm neg_ttlm = {};
+	const u16 maps[8] = {
+		0x0003, 0x0003, 0x0003, 0x0003,
+		0x0003, 0x0003, 0x0003, 0x0003,
+	};
+	u8 direction = 0;
+	int ret;
+
+	KUNIT_ASSERT_NOT_NULL(test, buf);
+
+	ttlm = build_neg_ttlm_elem(buf, elem_size, presence, bm_size, maps);
+
+	ret = ieee80211_parse_neg_ttlm(NULL, ttlm, &neg_ttlm, &direction);
+
+	KUNIT_EXPECT_EQ(test, ret, 0);
+	KUNIT_EXPECT_EQ(test, (int)direction, IEEE80211_TTLM_DIRECTION_BOTH);
+	/* All TIDs present: every downlink/uplink entry must be 0x0003. */
+	for (int tid = 0; tid < IEEE80211_TTLM_NUM_TIDS; tid++) {
+		KUNIT_EXPECT_EQ(test, (int)neg_ttlm.downlink[tid], 0x0003);
+		KUNIT_EXPECT_EQ(test, (int)neg_ttlm.uplink[tid],   0x0003);
+	}
+}
+
+static struct kunit_case mac80211_ttlm_test_cases[] = {
+	KUNIT_CASE(sparse_presence_no_oob_read),
+	KUNIT_CASE(dense_presence_baseline),
+	{}
+};
+
+static struct kunit_suite mac80211_ttlm = {
+	.name = "mac80211-ttlm",
+	.test_cases = mac80211_ttlm_test_cases,
+};
+
+kunit_test_suite(mac80211_ttlm);