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, 287 insertions, 0 deletions

diff --git a/fs/adfs/dir_fplus.c b/fs/adfs/dir_fplus.c
new file mode 100644
index 000000000..4a1592401
--- /dev/null
+++ b/fs/adfs/dir_fplus.c
@@ -0,0 +1,287 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/fs/adfs/dir_fplus.c
+ *
+ *  Copyright (C) 1997-1999 Russell King
+ */
+#include "adfs.h"
+#include "dir_fplus.h"
+
+/* Return the byte offset to directory entry pos */
+static unsigned int adfs_fplus_offset(const struct adfs_bigdirheader *h,
+				      unsigned int pos)
+{
+	return offsetof(struct adfs_bigdirheader, bigdirname) +
+	       ALIGN(le32_to_cpu(h->bigdirnamelen), 4) +
+	       pos * sizeof(struct adfs_bigdirentry);
+}
+
+static int adfs_fplus_validate_header(const struct adfs_bigdirheader *h)
+{
+	unsigned int size = le32_to_cpu(h->bigdirsize);
+	unsigned int len;
+
+	if (h->bigdirversion[0] != 0 || h->bigdirversion[1] != 0 ||
+	    h->bigdirversion[2] != 0 ||
+	    h->bigdirstartname != cpu_to_le32(BIGDIRSTARTNAME) ||
+	    !size || size & 2047 || size > SZ_4M)
+		return -EIO;
+
+	size -= sizeof(struct adfs_bigdirtail) +
+		offsetof(struct adfs_bigdirheader, bigdirname);
+
+	/* Check that bigdirnamelen fits within the directory */
+	len = ALIGN(le32_to_cpu(h->bigdirnamelen), 4);
+	if (len > size)
+		return -EIO;
+
+	size -= len;
+
+	/* Check that bigdirnamesize fits within the directory */
+	len = le32_to_cpu(h->bigdirnamesize);
+	if (len > size)
+		return -EIO;
+
+	size -= len;
+
+	/*
+	 * Avoid division, we know that absolute maximum number of entries
+	 * can not be so large to cause overflow of the multiplication below.
+	 */
+	len = le32_to_cpu(h->bigdirentries);
+	if (len > SZ_4M / sizeof(struct adfs_bigdirentry) ||
+	    len * sizeof(struct adfs_bigdirentry) > size)
+		return -EIO;
+
+	return 0;
+}
+
+static int adfs_fplus_validate_tail(const struct adfs_bigdirheader *h,
+				    const struct adfs_bigdirtail *t)
+{
+	if (t->bigdirendname != cpu_to_le32(BIGDIRENDNAME) ||
+	    t->bigdirendmasseq != h->startmasseq ||
+	    t->reserved[0] != 0 || t->reserved[1] != 0)
+		return -EIO;
+
+	return 0;
+}
+
+static u8 adfs_fplus_checkbyte(struct adfs_dir *dir)
+{
+	struct adfs_bigdirheader *h = dir->bighead;
+	struct adfs_bigdirtail *t = dir->bigtail;
+	unsigned int end, bs, bi, i;
+	__le32 *bp;
+	u32 dircheck;
+
+	end = adfs_fplus_offset(h, le32_to_cpu(h->bigdirentries)) +
+		le32_to_cpu(h->bigdirnamesize);
+
+	/* Accumulate the contents of the header, entries and names */
+	for (dircheck = 0, bi = 0; end; bi++) {
+		bp = (void *)dir->bhs[bi]->b_data;
+		bs = dir->bhs[bi]->b_size;
+		if (bs > end)
+			bs = end;
+
+		for (i = 0; i < bs; i += sizeof(u32))
+			dircheck = ror32(dircheck, 13) ^ le32_to_cpup(bp++);
+
+		end -= bs;
+	}
+
+	/* Accumulate the contents of the tail except for the check byte */
+	dircheck = ror32(dircheck, 13) ^ le32_to_cpu(t->bigdirendname);
+	dircheck = ror32(dircheck, 13) ^ t->bigdirendmasseq;
+	dircheck = ror32(dircheck, 13) ^ t->reserved[0];
+	dircheck = ror32(dircheck, 13) ^ t->reserved[1];
+
+	return dircheck ^ dircheck >> 8 ^ dircheck >> 16 ^ dircheck >> 24;
+}
+
+static int adfs_fplus_read(struct super_block *sb, u32 indaddr,
+			   unsigned int size, struct adfs_dir *dir)
+{
+	struct adfs_bigdirheader *h;
+	struct adfs_bigdirtail *t;
+	unsigned int dirsize;
+	int ret;
+
+	/* Read first buffer */
+	ret = adfs_dir_read_buffers(sb, indaddr, sb->s_blocksize, dir);
+	if (ret)
+		return ret;
+
+	dir->bighead = h = (void *)dir->bhs[0]->b_data;
+	ret = adfs_fplus_validate_header(h);
+	if (ret) {
+		adfs_error(sb, "dir %06x has malformed header", indaddr);
+		goto out;
+	}
+
+	dirsize = le32_to_cpu(h->bigdirsize);
+	if (size && dirsize != size) {
+		adfs_msg(sb, KERN_WARNING,
+			 "dir %06x header size %X does not match directory size %X",
+			 indaddr, dirsize, size);
+	}
+
+	/* Read remaining buffers */
+	ret = adfs_dir_read_buffers(sb, indaddr, dirsize, dir);
+	if (ret)
+		return ret;
+
+	dir->bigtail = t = (struct adfs_bigdirtail *)
+		(dir->bhs[dir->nr_buffers - 1]->b_data + (sb->s_blocksize - 8));
+
+	ret = adfs_fplus_validate_tail(h, t);
+	if (ret) {
+		adfs_error(sb, "dir %06x has malformed tail", indaddr);
+		goto out;
+	}
+
+	if (adfs_fplus_checkbyte(dir) != t->bigdircheckbyte) {
+		adfs_error(sb, "dir %06x checkbyte mismatch\n", indaddr);
+		goto out;
+	}
+
+	dir->parent_id = le32_to_cpu(h->bigdirparent);
+	return 0;
+
+out:
+	adfs_dir_relse(dir);
+
+	return ret;
+}
+
+static int
+adfs_fplus_setpos(struct adfs_dir *dir, unsigned int fpos)
+{
+	int ret = -ENOENT;
+
+	if (fpos <= le32_to_cpu(dir->bighead->bigdirentries)) {
+		dir->pos = fpos;
+		ret = 0;
+	}
+
+	return ret;
+}
+
+static int
+adfs_fplus_getnext(struct adfs_dir *dir, struct object_info *obj)
+{
+	struct adfs_bigdirheader *h = dir->bighead;
+	struct adfs_bigdirentry bde;
+	unsigned int offset;
+	int ret;
+
+	if (dir->pos >= le32_to_cpu(h->bigdirentries))
+		return -ENOENT;
+
+	offset = adfs_fplus_offset(h, dir->pos);
+
+	ret = adfs_dir_copyfrom(&bde, dir, offset,
+				sizeof(struct adfs_bigdirentry));
+	if (ret)
+		return ret;
+
+	obj->loadaddr = le32_to_cpu(bde.bigdirload);
+	obj->execaddr = le32_to_cpu(bde.bigdirexec);
+	obj->size     = le32_to_cpu(bde.bigdirlen);
+	obj->indaddr  = le32_to_cpu(bde.bigdirindaddr);
+	obj->attr     = le32_to_cpu(bde.bigdirattr);
+	obj->name_len = le32_to_cpu(bde.bigdirobnamelen);
+
+	offset = adfs_fplus_offset(h, le32_to_cpu(h->bigdirentries));
+	offset += le32_to_cpu(bde.bigdirobnameptr);
+
+	ret = adfs_dir_copyfrom(obj->name, dir, offset, obj->name_len);
+	if (ret)
+		return ret;
+
+	adfs_object_fixup(dir, obj);
+
+	dir->pos += 1;
+
+	return 0;
+}
+
+static int adfs_fplus_iterate(struct adfs_dir *dir, struct dir_context *ctx)
+{
+	struct object_info obj;
+
+	if ((ctx->pos - 2) >> 32)
+		return 0;
+
+	if (adfs_fplus_setpos(dir, ctx->pos - 2))
+		return 0;
+
+	while (!adfs_fplus_getnext(dir, &obj)) {
+		if (!dir_emit(ctx, obj.name, obj.name_len,
+			      obj.indaddr, DT_UNKNOWN))
+			break;
+		ctx->pos++;
+	}
+
+	return 0;
+}
+
+static int adfs_fplus_update(struct adfs_dir *dir, struct object_info *obj)
+{
+	struct adfs_bigdirheader *h = dir->bighead;
+	struct adfs_bigdirentry bde;
+	int offset, end, ret;
+
+	offset = adfs_fplus_offset(h, 0) - sizeof(bde);
+	end = adfs_fplus_offset(h, le32_to_cpu(h->bigdirentries));
+
+	do {
+		offset += sizeof(bde);
+		if (offset >= end) {
+			adfs_error(dir->sb, "unable to locate entry to update");
+			return -ENOENT;
+		}
+		ret = adfs_dir_copyfrom(&bde, dir, offset, sizeof(bde));
+		if (ret) {
+			adfs_error(dir->sb, "error reading directory entry");
+			return -ENOENT;
+		}
+	} while (le32_to_cpu(bde.bigdirindaddr) != obj->indaddr);
+
+	bde.bigdirload    = cpu_to_le32(obj->loadaddr);
+	bde.bigdirexec    = cpu_to_le32(obj->execaddr);
+	bde.bigdirlen     = cpu_to_le32(obj->size);
+	bde.bigdirindaddr = cpu_to_le32(obj->indaddr);
+	bde.bigdirattr    = cpu_to_le32(obj->attr);
+
+	return adfs_dir_copyto(dir, offset, &bde, sizeof(bde));
+}
+
+static int adfs_fplus_commit(struct adfs_dir *dir)
+{
+	int ret;
+
+	/* Increment directory sequence number */
+	dir->bighead->startmasseq += 1;
+	dir->bigtail->bigdirendmasseq += 1;
+
+	/* Update directory check byte */
+	dir->bigtail->bigdircheckbyte = adfs_fplus_checkbyte(dir);
+
+	/* Make sure the directory still validates correctly */
+	ret = adfs_fplus_validate_header(dir->bighead);
+	if (ret == 0)
+		ret = adfs_fplus_validate_tail(dir->bighead, dir->bigtail);
+
+	return ret;
+}
+
+const struct adfs_dir_ops adfs_fplus_dir_ops = {
+	.read		= adfs_fplus_read,
+	.iterate	= adfs_fplus_iterate,
+	.setpos		= adfs_fplus_setpos,
+	.getnext	= adfs_fplus_getnext,
+	.update		= adfs_fplus_update,
+	.commit		= adfs_fplus_commit,
+};