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, 157 insertions, 0 deletions

diff --git a/fs/hfsplus/part_tbl.c b/fs/hfsplus/part_tbl.c
new file mode 100644
index 000000000..9ec21664e
--- /dev/null
+++ b/fs/hfsplus/part_tbl.c
@@ -0,0 +1,157 @@
+/*
+ * linux/fs/hfsplus/part_tbl.c
+ *
+ * Copyright (C) 1996-1997  Paul H. Hargrove
+ * This file may be distributed under the terms of
+ * the GNU General Public License.
+ *
+ * Original code to handle the new style Mac partition table based on
+ * a patch contributed by Holger Schemel (aeglos@valinor.owl.de).
+ *
+ * In function preconditions the term "valid" applied to a pointer to
+ * a structure means that the pointer is non-NULL and the structure it
+ * points to has all fields initialized to consistent values.
+ *
+ */
+
+#include <linux/slab.h>
+#include "hfsplus_fs.h"
+
+/* offsets to various blocks */
+#define HFS_DD_BLK		0 /* Driver Descriptor block */
+#define HFS_PMAP_BLK		1 /* First block of partition map */
+#define HFS_MDB_BLK		2 /* Block (w/i partition) of MDB */
+
+/* magic numbers for various disk blocks */
+#define HFS_DRVR_DESC_MAGIC	0x4552 /* "ER": driver descriptor map */
+#define HFS_OLD_PMAP_MAGIC	0x5453 /* "TS": old-type partition map */
+#define HFS_NEW_PMAP_MAGIC	0x504D /* "PM": new-type partition map */
+#define HFS_SUPER_MAGIC		0x4244 /* "BD": HFS MDB (super block) */
+#define HFS_MFS_SUPER_MAGIC	0xD2D7 /* MFS MDB (super block) */
+
+/*
+ * The new style Mac partition map
+ *
+ * For each partition on the media there is a physical block (512-byte
+ * block) containing one of these structures.  These blocks are
+ * contiguous starting at block 1.
+ */
+struct new_pmap {
+	__be16	pmSig;		/* signature */
+	__be16	reSigPad;	/* padding */
+	__be32	pmMapBlkCnt;	/* partition blocks count */
+	__be32	pmPyPartStart;	/* physical block start of partition */
+	__be32	pmPartBlkCnt;	/* physical block count of partition */
+	u8	pmPartName[32];	/* (null terminated?) string
+				   giving the name of this
+				   partition */
+	u8	pmPartType[32];	/* (null terminated?) string
+				   giving the type of this
+				   partition */
+	/* a bunch more stuff we don't need */
+} __packed;
+
+/*
+ * The old style Mac partition map
+ *
+ * The partition map consists for a 2-byte signature followed by an
+ * array of these structures.  The map is terminated with an all-zero
+ * one of these.
+ */
+struct old_pmap {
+	__be16		pdSig;	/* Signature bytes */
+	struct old_pmap_entry {
+		__be32	pdStart;
+		__be32	pdSize;
+		__be32	pdFSID;
+	}	pdEntry[42];
+} __packed;
+
+static int hfs_parse_old_pmap(struct super_block *sb, struct old_pmap *pm,
+		sector_t *part_start, sector_t *part_size)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+	int i;
+
+	for (i = 0; i < 42; i++) {
+		struct old_pmap_entry *p = &pm->pdEntry[i];
+
+		if (p->pdStart && p->pdSize &&
+		    p->pdFSID == cpu_to_be32(0x54465331)/*"TFS1"*/ &&
+		    (sbi->part < 0 || sbi->part == i)) {
+			*part_start += be32_to_cpu(p->pdStart);
+			*part_size = be32_to_cpu(p->pdSize);
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
+
+static int hfs_parse_new_pmap(struct super_block *sb, void *buf,
+		struct new_pmap *pm, sector_t *part_start, sector_t *part_size)
+{
+	struct hfsplus_sb_info *sbi = HFSPLUS_SB(sb);
+	int size = be32_to_cpu(pm->pmMapBlkCnt);
+	int buf_size = hfsplus_min_io_size(sb);
+	int res;
+	int i = 0;
+
+	do {
+		if (!memcmp(pm->pmPartType, "Apple_HFS", 9) &&
+		    (sbi->part < 0 || sbi->part == i)) {
+			*part_start += be32_to_cpu(pm->pmPyPartStart);
+			*part_size = be32_to_cpu(pm->pmPartBlkCnt);
+			return 0;
+		}
+
+		if (++i >= size)
+			return -ENOENT;
+
+		pm = (struct new_pmap *)((u8 *)pm + HFSPLUS_SECTOR_SIZE);
+		if ((u8 *)pm - (u8 *)buf >= buf_size) {
+			res = hfsplus_submit_bio(sb,
+						 *part_start + HFS_PMAP_BLK + i,
+						 buf, (void **)&pm, REQ_OP_READ);
+			if (res)
+				return res;
+		}
+	} while (pm->pmSig == cpu_to_be16(HFS_NEW_PMAP_MAGIC));
+
+	return -ENOENT;
+}
+
+/*
+ * Parse the partition map looking for the start and length of a
+ * HFS/HFS+ partition.
+ */
+int hfs_part_find(struct super_block *sb,
+		sector_t *part_start, sector_t *part_size)
+{
+	void *buf, *data;
+	int res;
+
+	buf = kmalloc(hfsplus_min_io_size(sb), GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	res = hfsplus_submit_bio(sb, *part_start + HFS_PMAP_BLK,
+				 buf, &data, REQ_OP_READ);
+	if (res)
+		goto out;
+
+	switch (be16_to_cpu(*((__be16 *)data))) {
+	case HFS_OLD_PMAP_MAGIC:
+		res = hfs_parse_old_pmap(sb, data, part_start, part_size);
+		break;
+	case HFS_NEW_PMAP_MAGIC:
+		res = hfs_parse_new_pmap(sb, buf, data, part_start, part_size);
+		break;
+	default:
+		res = -ENOENT;
+		break;
+	}
+out:
+	kfree(buf);
+	return res;
+}